NOISSUE change uvim folder name to mnv

Signed-off-by: Mehmet Samet Duman <yongdohyun@projecttick.org>

1 files changed, 3631 insertions, 0 deletions

diff --git a/mnv/src/testdir/test_diffmode.mnv b/mnv/src/testdir/test_diffmode.mnv
new file mode 100644
index 0000000000..72366e6928
--- /dev/null
+++ b/mnv/src/testdir/test_diffmode.mnv
@@ -0,0 +1,3631 @@
+" Tests for diff mode
+
+source util/screendump.mnv
+
+func Test_diff_fold_sync()
+  enew!
+  let g:update_count = 0
+  au DiffUpdated * let g:update_count += 1
+
+  let l = range(50)
+  call setline(1, l)
+  diffthis
+  let winone = win_getid()
+  new
+  let l[25] = 'diff'
+  call setline(1, l)
+  diffthis
+  let wintwo = win_getid()
+  " line 15 is inside the closed fold
+  call assert_equal(19, foldclosedend(10))
+  call win_gotoid(winone)
+  call assert_equal(19, foldclosedend(10))
+  " open the fold
+  normal zv
+  call assert_equal(-1, foldclosedend(10))
+  " fold in other window must have opened too
+  call win_gotoid(wintwo)
+  call assert_equal(-1, foldclosedend(10))
+
+  " cursor position is in sync
+  normal 23G
+  call win_gotoid(winone)
+  call assert_equal(23, getcurpos()[1])
+
+  " depending on how redraw is done DiffUpdated may be triggered once or twice
+  call assert_inrange(1, 2, g:update_count)
+  au! DiffUpdated
+
+  windo diffoff
+  close!
+  set nomodified
+endfunc
+
+func Test_vert_split()
+  set diffopt=filler
+  call Common_vert_split()
+  set diffopt&
+endfunc
+
+" Test for diff folding redraw after last diff is resolved
+func Test_diff_fold_redraw()
+  " Set up two files with a minimal case.
+  call writefile(['Paragraph 1', '', 'Paragraph 2', '', 'Paragraph 3'], 'Xfile1')
+  call writefile(['Paragraph 1', '', 'Paragraph 3'], 'Xfile2')
+
+  " Open in diff mode.
+  edit Xfile1
+  vert diffsplit Xfile2
+
+  " Go to the diff and apply :diffput to copy Paragraph 2 to Xfile2.
+  wincmd l
+  3
+  diffput
+
+  " Check that the folds in both windows are closed and extend from the first
+  " line of the buffer to the last line of the buffer.
+  call assert_equal(1, foldclosed(line("$")))
+  wincmd h
+  call assert_equal(1, foldclosed(line("$")))
+
+  " Clean up.
+  bwipe!
+  bwipe!
+  call delete('Xfile1')
+  call delete('Xfile2')
+endfunc
+
+func Test_vert_split_internal()
+  set diffopt=internal,filler
+  call Common_vert_split()
+  set diffopt&
+endfunc
+
+func Common_vert_split()
+  " Disable the title to avoid xterm keeping the wrong one.
+  set notitle noicon
+  new
+  let l = ['1 aa', '2 bb', '3 cc', '4 dd', '5 ee']
+  call setline(1, l)
+  w! Xtest
+  normal dd
+  $
+  put
+  normal kkrXoxxx
+  w! Xtest2
+  file Nop
+  normal ggoyyyjjjozzzz
+  set foldmethod=marker foldcolumn=4
+  call assert_equal(0, &diff)
+  call assert_equal('marker', &foldmethod)
+  call assert_equal(4, &foldcolumn)
+  call assert_equal(0, &scrollbind)
+  call assert_equal(0, &cursorbind)
+  call assert_equal(1, &wrap)
+
+  vert diffsplit Xtest
+  vert diffsplit Xtest2
+  call assert_equal(1, &diff)
+  call assert_equal('diff', &foldmethod)
+  call assert_equal(2, &foldcolumn)
+  call assert_equal(1, &scrollbind)
+  call assert_equal(1, &cursorbind)
+  call assert_equal(0, &wrap)
+
+  let diff_fdm = &fdm
+  let diff_fdc = &fdc
+  " repeat entering diff mode here to see if this saves the wrong settings
+  diffthis
+  " jump to second window for a moment to have filler line appear at start of
+  " first window
+  wincmd w
+  normal gg
+  wincmd p
+  normal gg
+  call assert_equal(2, winline())
+  normal j
+  call assert_equal(4, winline())
+  normal j
+  call assert_equal(5, winline())
+  normal j
+  call assert_equal(6, winline())
+  normal j
+  call assert_equal(8, winline())
+  normal j
+  call assert_equal(9, winline())
+
+  wincmd w
+  normal gg
+  call assert_equal(1, winline())
+  normal j
+  call assert_equal(2, winline())
+  normal j
+  call assert_equal(4, winline())
+  normal j
+  call assert_equal(5, winline())
+  normal j
+  call assert_equal(8, winline())
+
+  wincmd w
+  normal gg
+  call assert_equal(2, winline())
+  normal j
+  call assert_equal(3, winline())
+  normal j
+  call assert_equal(4, winline())
+  normal j
+  call assert_equal(5, winline())
+  normal j
+  call assert_equal(6, winline())
+  normal j
+  call assert_equal(7, winline())
+  normal j
+  call assert_equal(8, winline())
+
+  " Test diffoff
+  diffoff!
+  1wincmd w
+  let &diff = 1
+  let &fdm = diff_fdm
+  let &fdc = diff_fdc
+  4wincmd w
+  diffoff!
+  1wincmd w
+  call assert_equal(0, &diff)
+  call assert_equal('marker', &foldmethod)
+  call assert_equal(4, &foldcolumn)
+  call assert_equal(0, &scrollbind)
+  call assert_equal(0, &cursorbind)
+  call assert_equal(1, &wrap)
+
+  wincmd w
+  call assert_equal(0, &diff)
+  call assert_equal('marker', &foldmethod)
+  call assert_equal(4, &foldcolumn)
+  call assert_equal(0, &scrollbind)
+  call assert_equal(0, &cursorbind)
+  call assert_equal(1, &wrap)
+
+  wincmd w
+  call assert_equal(0, &diff)
+  call assert_equal('marker', &foldmethod)
+  call assert_equal(4, &foldcolumn)
+  call assert_equal(0, &scrollbind)
+  call assert_equal(0, &cursorbind)
+  call assert_equal(1, &wrap)
+
+  call delete('Xtest')
+  call delete('Xtest2')
+  windo bw!
+endfunc
+
+func Test_filler_lines()
+  " Test that diffing shows correct filler lines
+  enew!
+  put =range(4,10)
+  1d _
+  vnew
+  put =range(1,10)
+  1d _
+  windo diffthis
+  wincmd h
+  call assert_equal(1, line('w0'))
+  unlet! diff_fdm diff_fdc
+  windo diffoff
+  bwipe!
+  enew!
+endfunc
+
+func Test_diffget_diffput()
+  enew!
+  let l = range(50)
+  call setline(1, l)
+  call assert_fails('diffget', 'E99:')
+  diffthis
+  call assert_fails('diffget', 'E100:')
+  new
+  let l[10] = 'one'
+  let l[20] = 'two'
+  let l[30] = 'three'
+  let l[40] = 'four'
+  call setline(1, l)
+  diffthis
+  call assert_equal('one', getline(11))
+  11diffget
+  call assert_equal('10', getline(11))
+  21diffput
+  wincmd w
+  call assert_equal('two', getline(21))
+  normal 31Gdo
+  call assert_equal('three', getline(31))
+  call assert_equal('40', getline(41))
+  normal 41Gdp
+  wincmd w
+  call assert_equal('40', getline(41))
+  new
+  diffthis
+  call assert_fails('diffget', 'E101:')
+
+  windo diffoff
+  %bwipe!
+endfunc
+
+" Test putting two changes from one buffer to another
+func Test_diffput_two()
+  new a
+  let win_a = win_getid()
+  call setline(1, range(1, 10))
+  diffthis
+  new b
+  let win_b = win_getid()
+  call setline(1, range(1, 10))
+  8del
+  5del
+  diffthis
+  call win_gotoid(win_a)
+  %diffput
+  call win_gotoid(win_b)
+  call assert_equal(map(range(1, 10), 'string(v:val)'), getline(1, '$'))
+  bwipe! a
+  bwipe! b
+endfunc
+
+" Test for :diffget/:diffput with a range that is inside a diff chunk
+func Test_diffget_diffput_range()
+  call setline(1, range(1, 10))
+  new
+  call setline(1, range(11, 20))
+  windo diffthis
+  3,5diffget
+  call assert_equal(['13', '14', '15'], getline(3, 5))
+  call setline(1, range(1, 10))
+  4,8diffput
+  wincmd p
+  call assert_equal(['13', '4', '5', '6', '7', '8', '19'], getline(3, 9))
+  %bw!
+endfunc
+
+" Test :diffget/:diffput handling of added/deleted lines
+func Test_diffget_diffput_deleted_lines()
+  call setline(1, ['2','4','6'])
+  diffthis
+  new
+  call setline(1, range(1,7))
+  diffthis
+  wincmd w
+
+  3,3diffget " get nothing
+  call assert_equal(['2', '4', '6'], getline(1, '$'))
+  3,4diffget " get the last insertion past the end of file
+  call assert_equal(['2', '4', '6', '7'], getline(1, '$'))
+  0,1diffget " get the first insertion above first line
+  call assert_equal(['1', '2', '4', '6', '7'], getline(1, '$'))
+
+  " When using non-range diffget on the last line, it should get the
+  " change above or at the line as usual, but if the only change is below the
+  " last line, diffget should get that instead.
+  1,$delete
+  call setline(1, ['2','4','6'])
+  diffupdate
+  norm Gdo
+  call assert_equal(['2', '4', '5', '6'], getline(1, '$'))
+  norm Gdo
+  call assert_equal(['2', '4', '5', '6', '7'], getline(1, '$'))
+
+  " Test non-range diffput on last line with the same logic
+  1,$delete
+  call setline(1, ['2','4','6'])
+  diffupdate
+  norm Gdp
+  wincmd w
+  call assert_equal(['1', '2', '3', '4', '6', '7'], getline(1, '$'))
+  wincmd w
+  norm Gdp
+  wincmd w
+  call assert_equal(['1', '2', '3', '4', '6'], getline(1, '$'))
+  call setline(1, range(1,7))
+  diffupdate
+  wincmd w
+
+  " Test that 0,$+1 will get/put all changes from/to the other buffer
+  1,$delete
+  call setline(1, ['2','4','6'])
+  diffupdate
+  0,$+1diffget
+  call assert_equal(['1', '2', '3', '4', '5', '6', '7'], getline(1, '$'))
+  1,$delete
+  call setline(1, ['2','4','6'])
+  diffupdate
+  0,$+1diffput
+  wincmd w
+  call assert_equal(['2', '4', '6'], getline(1, '$'))
+  %bw!
+endfunc
+
+" Test for :diffget/:diffput with an empty buffer and a non-empty buffer
+func Test_diffget_diffput_empty_buffer()
+  %d _
+  new
+  call setline(1, 'one')
+  windo diffthis
+  diffget
+  call assert_equal(['one'], getline(1, '$'))
+  %d _
+  diffput
+  wincmd p
+  call assert_equal([''], getline(1, '$'))
+  %bw!
+endfunc
+
+" :diffput and :diffget completes names of buffers which
+" are in diff mode and which are different than current buffer.
+" No completion when the current window is not in diff mode.
+func Test_diffget_diffput_completion()
+  e            Xdiff1 | diffthis
+  botright new Xdiff2
+  botright new Xdiff3 | split | diffthis
+  botright new Xdiff4 | diffthis
+
+  wincmd t
+  call assert_equal('Xdiff1', bufname('%'))
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput Xdiff3 Xdiff4', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget Xdiff3 Xdiff4', @:)
+  call assert_equal(['Xdiff3', 'Xdiff4'], getcompletion('', 'diff_buffer'))
+
+  " Xdiff2 is not in diff mode, so no completion for :diffput, :diffget
+  wincmd j
+  call assert_equal('Xdiff2', bufname('%'))
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput ', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget ', @:)
+  call assert_equal([], getcompletion('', 'diff_buffer'))
+
+  " Xdiff3 is split in 2 windows, only the top one is in diff mode.
+  " So completion of :diffput :diffget only happens in the top window.
+  wincmd j
+  call assert_equal('Xdiff3', bufname('%'))
+  call assert_equal(1, &diff)
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput Xdiff1 Xdiff4', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget Xdiff1 Xdiff4', @:)
+  call assert_equal(['Xdiff1', 'Xdiff4'], getcompletion('', 'diff_buffer'))
+
+  wincmd j
+  call assert_equal('Xdiff3', bufname('%'))
+  call assert_equal(0, &diff)
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput ', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget ', @:)
+  call assert_equal([], getcompletion('', 'diff_buffer'))
+
+  wincmd j
+  call assert_equal('Xdiff4', bufname('%'))
+  call feedkeys(":diffput \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffput Xdiff1 Xdiff3', @:)
+  call feedkeys(":diffget \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"diffget Xdiff1 Xdiff3', @:)
+  call assert_equal(['Xdiff1', 'Xdiff3'], getcompletion('', 'diff_buffer'))
+
+  %bwipe
+endfunc
+
+func Test_dp_do_buffer()
+  e! one
+  let bn1=bufnr('%')
+  let l = range(60)
+  call setline(1, l)
+  diffthis
+
+  new two
+  let l[10] = 'one'
+  let l[20] = 'two'
+  let l[30] = 'three'
+  let l[40] = 'four'
+  let l[50] = 'five'
+  call setline(1, l)
+  diffthis
+
+  " dp and do with invalid buffer number.
+  11
+  call assert_fails('norm 99999dp', 'E102:')
+  call assert_fails('norm 99999do', 'E102:')
+  call assert_fails('diffput non_existing_buffer', 'E94:')
+  call assert_fails('diffget non_existing_buffer', 'E94:')
+
+  " dp and do with valid buffer number.
+  call assert_equal('one', getline('.'))
+  exe 'norm ' . bn1 . 'do'
+  call assert_equal('10', getline('.'))
+  21
+  call assert_equal('two', getline('.'))
+  diffget one
+  call assert_equal('20', getline('.'))
+
+  31
+  exe 'norm ' . bn1 . 'dp'
+  41
+  diffput one
+  wincmd w
+  31
+  call assert_equal('three', getline('.'))
+  41
+  call assert_equal('four', getline('.'))
+
+  " dp and do with buffer number which is not in diff mode.
+  new not_in_diff_mode
+  let bn3=bufnr('%')
+  wincmd w
+  51
+  call assert_fails('exe "norm" . bn3 . "dp"', 'E103:')
+  call assert_fails('exe "norm" . bn3 . "do"', 'E103:')
+  call assert_fails('diffput not_in_diff_mode', 'E94:')
+  call assert_fails('diffget not_in_diff_mode', 'E94:')
+
+  windo diffoff
+  %bwipe!
+endfunc
+
+func Test_do_lastline()
+  e! one
+  call setline(1, ['1','2','3','4','5','6'])
+  diffthis
+
+  new two
+  call setline(1, ['2','4','5'])
+  diffthis
+
+  1
+  norm dp]c
+  norm dp]c
+  wincmd w
+  call assert_equal(4, line('$'))
+  norm G
+  norm do
+  call assert_equal(3, line('$'))
+
+  windo diffoff
+  %bwipe!
+endfunc
+
+func Test_diffoff()
+  enew!
+  call setline(1, ['Two', 'Three'])
+  redraw
+  let normattr = screenattr(1, 1)
+  diffthis
+  botright vert new
+  call setline(1, ['One', '', 'Two', 'Three'])
+  diffthis
+  redraw
+  call assert_notequal(normattr, 1->screenattr(1))
+  diffoff!
+  redraw
+  call assert_equal(normattr, screenattr(1, 1))
+  bwipe!
+  bwipe!
+endfunc
+
+func Common_icase_test()
+  edit one
+  call setline(1, ['One', 'Two', 'Three', 'Four', 'Fi#vϵ', 'Si⃗x', 'Se⃗ve⃗n'])
+  redraw
+  let normattr = screenattr(1, 1)
+  diffthis
+
+  botright vert new two
+  call setline(1, ['one', 'TWO', 'Three ', 'Four', 'fI=VΕ', 'SI⃗x', 'SEvE⃗n'])
+  diffthis
+
+  redraw
+  call assert_equal(normattr, screenattr(1, 1))
+  call assert_equal(normattr, screenattr(2, 1))
+  call assert_notequal(normattr, screenattr(3, 1))
+  call assert_equal(normattr, screenattr(4, 1))
+  call assert_equal(normattr, screenattr(6, 2))
+  call assert_notequal(normattr, screenattr(7, 2))
+
+  let dtextattr = screenattr(5, 3)
+  call assert_notequal(dtextattr, screenattr(5, 1))
+  call assert_notequal(dtextattr, screenattr(5, 5))
+  call assert_notequal(dtextattr, screenattr(7, 4))
+
+  diffoff!
+  %bwipe!
+endfunc
+
+func Test_diffopt_icase()
+  set diffopt=icase,foldcolumn:0
+  call Common_icase_test()
+  set diffopt&
+endfunc
+
+func Test_diffopt_icase_internal()
+  set diffopt=icase,foldcolumn:0,internal
+  call Common_icase_test()
+  set diffopt&
+endfunc
+
+func Common_iwhite_test()
+  edit one
+  " Difference in trailing spaces and amount of spaces should be ignored,
+  " but not other space differences.
+  call setline(1, ["One \t", 'Two', 'Three', 'one two', 'one two', 'Four'])
+  redraw
+  let normattr = screenattr(1, 1)
+  diffthis
+
+  botright vert new two
+  call setline(1, ["One\t ", "Two\t ", 'Three', 'one   two', 'onetwo', ' Four'])
+  diffthis
+
+  redraw
+  call assert_equal(normattr, screenattr(1, 1))
+  call assert_equal(normattr, screenattr(2, 1))
+  call assert_equal(normattr, screenattr(3, 1))
+  call assert_equal(normattr, screenattr(4, 1))
+  call assert_notequal(normattr, screenattr(5, 1))
+  call assert_notequal(normattr, screenattr(6, 1))
+
+  diffoff!
+  %bwipe!
+endfunc
+
+func Test_diffopt_iwhite()
+  set diffopt=iwhite,foldcolumn:0
+  call Common_iwhite_test()
+  set diffopt&
+endfunc
+
+func Test_diffopt_iwhite_internal()
+  set diffopt=internal,iwhite,foldcolumn:0
+  call Common_iwhite_test()
+  set diffopt&
+endfunc
+
+func Test_diffopt_context()
+  enew!
+  call setline(1, ['1', '2', '3', '4', '5', '6', '7'])
+  diffthis
+  new
+  call setline(1, ['1', '2', '3', '4', '5x', '6', '7'])
+  diffthis
+
+  set diffopt=context:2
+  call assert_equal('+--  2 lines: 1', foldtextresult(1))
+  set diffopt=internal,context:2
+  call assert_equal('+--  2 lines: 1', foldtextresult(1))
+
+  set diffopt=context:1
+  call assert_equal('+--  3 lines: 1', foldtextresult(1))
+  set diffopt=internal,context:1
+  call assert_equal('+--  3 lines: 1', foldtextresult(1))
+
+  diffoff!
+  %bwipe!
+  set diffopt&
+endfunc
+
+func Test_diffopt_horizontal()
+  set diffopt=internal,horizontal
+  diffsplit
+
+  call assert_equal(&columns, winwidth(1))
+  call assert_equal(&columns, winwidth(2))
+  call assert_equal(&lines, winheight(1) + winheight(2) + 3)
+  call assert_inrange(0, 1, winheight(1) - winheight(2))
+
+  set diffopt&
+  diffoff!
+  %bwipe
+endfunc
+
+func Test_diffopt_vertical()
+  set diffopt=internal,vertical
+  diffsplit
+
+  call assert_equal(&lines - 2, winheight(1))
+  call assert_equal(&lines - 2, winheight(2))
+  call assert_equal(&columns, winwidth(1) + winwidth(2) + 1)
+  call assert_inrange(0, 1, winwidth(1) - winwidth(2))
+
+  set diffopt&
+  diffoff!
+  %bwipe
+endfunc
+
+func Test_diffopt_hiddenoff()
+  set diffopt=internal,filler,foldcolumn:0,hiddenoff
+  e! one
+  call setline(1, ['Two', 'Three'])
+  redraw
+  let normattr = screenattr(1, 1)
+  diffthis
+  botright vert new two
+  call setline(1, ['One', 'Four'])
+  diffthis
+  redraw
+  call assert_notequal(normattr, screenattr(1, 1))
+  set hidden
+  close
+  redraw
+  " should not diffing with hidden buffer two while 'hiddenoff' is enabled
+  call assert_equal(normattr, screenattr(1, 1))
+
+  bwipe!
+  bwipe!
+  set hidden& diffopt&
+endfunc
+
+func Test_diffoff_hidden()
+  set diffopt=internal,filler,foldcolumn:0
+  e! one
+  call setline(1, ['Two', 'Three'])
+  redraw
+  let normattr = screenattr(1, 1)
+  diffthis
+  botright vert new two
+  call setline(1, ['One', 'Four'])
+  diffthis
+  redraw
+  call assert_notequal(normattr, screenattr(1, 1))
+  set hidden
+  close
+  redraw
+  " diffing with hidden buffer two
+  call assert_notequal(normattr, screenattr(1, 1))
+  diffoff
+  redraw
+  call assert_equal(normattr, screenattr(1, 1))
+  diffthis
+  redraw
+  " still diffing with hidden buffer two
+  call assert_notequal(normattr, screenattr(1, 1))
+  diffoff!
+  redraw
+  call assert_equal(normattr, screenattr(1, 1))
+  diffthis
+  redraw
+  " no longer diffing with hidden buffer two
+  call assert_equal(normattr, screenattr(1, 1))
+
+  bwipe!
+  bwipe!
+  set hidden& diffopt&
+endfunc
+
+func Test_setting_cursor()
+  new Xtest1
+  put =range(1,90)
+  wq
+  new Xtest2
+  put =range(1,100)
+  wq
+
+  tabe Xtest2
+  $
+  diffsp Xtest1
+  tabclose
+
+  call delete('Xtest1')
+  call delete('Xtest2')
+endfunc
+
+func Test_diff_move_to()
+  new
+  call setline(1, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  diffthis
+  vnew
+  call setline(1, [1, '2x', 3, 4, 4, 5, '6x', 7, '8x', 9, '10x'])
+  diffthis
+  norm ]c
+  call assert_equal(2, line('.'))
+  norm 3]c
+  call assert_equal(9, line('.'))
+  norm 10]c
+  call assert_equal(11, line('.'))
+  norm [c
+  call assert_equal(9, line('.'))
+  norm 2[c
+  call assert_equal(5, line('.'))
+  norm 10[c
+  call assert_equal(2, line('.'))
+  %bwipe!
+endfunc
+
+func Test_diffexpr()
+  CheckExecutable diff
+
+  func DiffExpr()
+    " Prepend some text to check diff type detection
+    call writefile(['warning', '  message'], v:fname_out)
+    silent exe '!diff ' . v:fname_in . ' ' . v:fname_new . '>>' . v:fname_out
+  endfunc
+  set diffexpr=DiffExpr()
+  set diffopt=foldcolumn:0
+
+  enew!
+  call setline(1, ['one', 'two', 'three'])
+  redraw
+  let normattr = screenattr(1, 1)
+  diffthis
+
+  botright vert new
+  call setline(1, ['one', 'two', 'three.'])
+  diffthis
+
+  redraw
+  call assert_equal(normattr, screenattr(1, 1))
+  call assert_equal(normattr, screenattr(2, 1))
+  call assert_notequal(normattr, screenattr(3, 1))
+  diffoff!
+
+  " Try using a non-existing function for 'diffexpr'.
+  set diffexpr=NewDiffFunc()
+  call assert_fails('windo diffthis', ['E117:', 'E97:'])
+  diffoff!
+
+  " Using a script-local function
+  func s:NewDiffExpr()
+  endfunc
+  set diffexpr=s:NewDiffExpr()
+  call assert_equal(expand('<SID>') .. 'NewDiffExpr()', &diffexpr)
+  set diffexpr=<SID>NewDiffExpr()
+  call assert_equal(expand('<SID>') .. 'NewDiffExpr()', &diffexpr)
+
+  %bwipe!
+  set diffexpr& diffopt&
+  delfunc DiffExpr
+  delfunc s:NewDiffExpr
+endfunc
+
+func Test_diffpatch()
+  " The patch program on MS-Windows may fail or hang.
+  CheckExecutable patch
+  CheckUnix
+  new
+  insert
+***************
+*** 1,3 ****
+  1
+! 2
+  3
+--- 1,4 ----
+  1
+! 2x
+  3
++ 4
+.
+  saveas! Xpatch
+  bwipe!
+  new
+  call assert_fails('diffpatch Xpatch', 'E816:')
+
+  for name in ['Xpatch', 'Xpatch$HOME', 'Xpa''tch']
+    call setline(1, ['1', '2', '3'])
+    if name != 'Xpatch'
+      call rename('Xpatch', name)
+    endif
+    exe 'diffpatch ' . escape(name, '$')
+    call assert_equal(['1', '2x', '3', '4'], getline(1, '$'))
+    if name != 'Xpatch'
+      call rename(name, 'Xpatch')
+    endif
+    bwipe!
+  endfor
+
+  call delete('Xpatch')
+  bwipe!
+endfunc
+
+" FIXME: test fails, the Xresult file can't be read
+func No_Test_diffpatch_restricted()
+  let lines =<< trim END
+    call assert_fails('diffpatch NoSuchDiff', 'E145:')
+
+    call writefile(v:errors, 'Xresult')
+    qa!
+  END
+  call writefile(lines, 'Xrestricted', 'D')
+  if RunMNV([], [], '-Z --clean -S Xrestricted')
+    call assert_equal([], readfile('Xresult'))
+  endif
+  call delete('Xresult')
+endfunc
+
+func Test_diff_too_many_buffers()
+  for i in range(1, 8)
+    exe "new Xtest" . i
+    diffthis
+  endfor
+  new Xtest9
+  call assert_fails('diffthis', 'E96:')
+  %bwipe!
+endfunc
+
+func Test_diff_nomodifiable()
+  new
+  call setline(1, [1, 2, 3, 4])
+  setl nomodifiable
+  diffthis
+  vnew
+  call setline(1, ['1x', 2, 3, 3, 4])
+  diffthis
+  call assert_fails('norm dp', 'E793:')
+  setl nomodifiable
+  call assert_fails('norm do', 'E21:')
+  %bwipe!
+endfunc
+
+func Test_diff_hlID()
+  set diffopt=internal,filler
+  new
+  call setline(1, [1, 2, 3, 'Yz', 'a dxxg',])
+  diffthis
+  vnew
+  call setline(1, ['1x', 2, 'x', 3, 'yx', 'abc defg'])
+  diffthis
+  redraw
+
+  call diff_hlID(-1, 1)->synIDattr("name")->assert_equal("")
+
+  call diff_hlID(1, 1)->synIDattr("name")->assert_equal("DiffChange")
+  call diff_hlID(1, 2)->synIDattr("name")->assert_equal("DiffText")
+  call diff_hlID(2, 1)->synIDattr("name")->assert_equal("")
+  call diff_hlID(3, 1)->synIDattr("name")->assert_equal("DiffAdd")
+  eval 4->diff_hlID(1)->synIDattr("name")->assert_equal("")
+  call diff_hlID(5, 1)->synIDattr("name")->assert_equal("DiffText")
+  call diff_hlID(5, 2)->synIDattr("name")->assert_equal("DiffText")
+
+  set diffopt+=icase " test that caching is invalidated by diffopt change
+  call diff_hlID(5, 1)->synIDattr("name")->assert_equal("DiffChange")
+  set diffopt-=icase
+  call diff_hlID(5, 1)->synIDattr("name")->assert_equal("DiffText")
+
+  call diff_hlID(6, 1)->synIDattr("name")->assert_equal("DiffChange")
+  call diff_hlID(6, 2)->synIDattr("name")->assert_equal("DiffText")
+  call diff_hlID(6, 4)->synIDattr("name")->assert_equal("DiffText")
+  call diff_hlID(6, 7)->synIDattr("name")->assert_equal("DiffText")
+  call diff_hlID(6, 8)->synIDattr("name")->assert_equal("DiffChange")
+  set diffopt+=inline:char
+  call diff_hlID(6, 1)->synIDattr("name")->assert_equal("DiffChange")
+  call diff_hlID(6, 2)->synIDattr("name")->assert_equal("DiffTextAdd")
+  call diff_hlID(6, 4)->synIDattr("name")->assert_equal("DiffChange")
+  call diff_hlID(6, 7)->synIDattr("name")->assert_equal("DiffText")
+  call diff_hlID(6, 8)->synIDattr("name")->assert_equal("DiffChange")
+  set diffopt-=inline:char
+
+  wincmd w
+  call assert_equal(synIDattr(diff_hlID(1, 1), "name"), "DiffChange")
+  call assert_equal(synIDattr(diff_hlID(2, 1), "name"), "")
+  call assert_equal(synIDattr(diff_hlID(3, 1), "name"), "")
+
+  %bwipe!
+  set diffopt&
+endfunc
+
+func Test_diff_filler()
+  new
+  call setline(1, [1, 2, 3, 'x', 4])
+  diffthis
+  vnew
+  call setline(1, [1, 2, 'y', 'y', 3, 4])
+  diffthis
+  redraw
+
+  call assert_equal([0, 0, 0, 0, 0, 0, 0, 1, 0], map(range(-1, 7), 'v:val->diff_filler()'))
+  wincmd w
+  call assert_equal([0, 0, 0, 0, 2, 0, 0, 0], map(range(-1, 6), 'diff_filler(v:val)'))
+
+  %bwipe!
+endfunc
+
+func Test_diff_lastline()
+  enew!
+  only!
+  call setline(1, ['This is a ', 'line with five ', 'rows'])
+  diffthis
+  botright vert new
+  call setline(1, ['This is', 'a line with ', 'four rows'])
+  diffthis
+  1
+  call feedkeys("Je a\<CR>", 'tx')
+  call feedkeys("Je a\<CR>", 'tx')
+  let w1lines = winline()
+  wincmd w
+  $
+  let w2lines = winline()
+  call assert_equal(w2lines, w1lines)
+  bwipe!
+  bwipe!
+endfunc
+
+func WriteDiffFiles(buf, list1, list2)
+  call writefile(a:list1, 'Xdifile1')
+  call writefile(a:list2, 'Xdifile2')
+  if a:buf
+    call term_sendkeys(a:buf, ":checktime\<CR>")
+  endif
+endfunc
+
+func WriteDiffFiles3(buf, list1, list2, list3)
+  call writefile(a:list1, 'Xdifile1')
+  call writefile(a:list2, 'Xdifile2')
+  call writefile(a:list3, 'Xdifile3')
+  if a:buf
+    call term_sendkeys(a:buf, ":checktime\<CR>")
+  endif
+endfunc
+
+" Verify a screendump with both the internal and external diff.
+func VerifyBoth(buf, dumpfile, extra)
+  CheckScreendump
+
+  " trailing : for leaving the cursor on the command line
+  for cmd in [":set diffopt=filler" . a:extra . "\<CR>:", ":set diffopt+=internal\<CR>:"]
+    call term_sendkeys(a:buf, cmd)
+    if VerifyScreenDump(a:buf, a:dumpfile, {}, cmd =~ 'internal' ? 'internal' : 'external')
+      " don't let the next iteration overwrite the "failed" file.
+      return
+    endif
+  endfor
+
+  " also test unified diff
+  call term_sendkeys(a:buf, ":call SetupUnified()\<CR>:")
+  call term_sendkeys(a:buf, ":redraw!\<CR>:")
+  call VerifyScreenDump(a:buf, a:dumpfile, {}, 'unified')
+  call term_sendkeys(a:buf, ":call StopUnified()\<CR>:")
+endfunc
+
+" Verify a screendump with the internal diff only.
+func VerifyInternal(buf, dumpfile, extra)
+  CheckScreendump
+
+  call term_sendkeys(a:buf, ":diffupdate!\<CR>")
+  " trailing : for leaving the cursor on the command line
+  call term_sendkeys(a:buf, ":set diffopt=internal,filler" . a:extra . "\<CR>:")
+  call VerifyScreenDump(a:buf, a:dumpfile, {})
+endfunc
+
+func Test_diff_screen()
+  if has('bsd')
+    CheckExecutable gdiff
+  endif
+  if has('osxdarwin') && system('diff --version') =~ '^Apple diff'
+    throw 'Skipped: unified diff does not work properly on this macOS version'
+  endif
+
+  let g:test_is_flaky = 1
+  CheckScreendump
+  CheckFeature menu
+
+  let lines =<< trim END
+      func UnifiedDiffExpr()
+        " Prepend some text to check diff type detection
+        call writefile(['warning', '  message'], v:fname_out)
+        let diff = has('bsd') ? 'gdiff' : 'diff'
+        silent exe $'!{diff} -U0 {v:fname_in} {v:fname_new}>>{v:fname_out}'
+      endfunc
+      func SetupUnified()
+        set diffexpr=UnifiedDiffExpr()
+        diffupdate
+      endfunc
+      func StopUnified()
+        set diffexpr=
+      endfunc
+  END
+  call writefile(lines, 'XdiffSetup', 'D')
+
+  " clean up already existing swap files, just in case
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+
+  " Test 1: Add a line in beginning of file 2
+  call WriteDiffFiles(0, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  let buf = RunMNVInTerminal('-d -S XdiffSetup Xdifile1 Xdifile2', {})
+  " Set autoread mode, so that MNV won't complain once we re-write the test
+  " files
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  call VerifyBoth(buf, 'Test_diff_01', '')
+
+  " Test 2: Add a line in beginning of file 1
+  call WriteDiffFiles(buf, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  call VerifyBoth(buf, 'Test_diff_02', '')
+
+  " Test 3: Add a line at the end of file 2
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
+  call VerifyBoth(buf, 'Test_diff_03', '')
+
+  " Test 4: Add a line at the end of file 1
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  call VerifyBoth(buf, 'Test_diff_04', '')
+
+  " Test 5: Add a line in the middle of file 2, remove on at the end of file 1
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10])
+  call VerifyBoth(buf, 'Test_diff_05', '')
+
+  " Test 6: Add a line in the middle of file 1, remove on at the end of file 2
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
+  call VerifyBoth(buf, 'Test_diff_06', '')
+
+  " Variants on test 6 with different context settings
+  call term_sendkeys(buf, ":set diffopt+=context:2\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_06.2', {})
+  call term_sendkeys(buf, ":set diffopt-=context:2\<cr>")
+  call term_sendkeys(buf, ":set diffopt+=context:1\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_06.1', {})
+  call term_sendkeys(buf, ":set diffopt-=context:1\<cr>")
+  call term_sendkeys(buf, ":set diffopt+=context:0\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_06.0', {})
+  call term_sendkeys(buf, ":set diffopt-=context:0\<cr>")
+
+  " Test 7 - 9: Test normal/patience/histogram diff algorithm
+  call WriteDiffFiles(buf, ['#include <stdio.h>', '', '// Frobs foo heartily', 'int frobnitz(int foo)', '{',
+      \ '    int i;', '    for(i = 0; i < 10; i++)', '    {', '        printf("Your answer is: ");',
+      \ '        printf("%d\n", foo);', '    }', '}', '', 'int fact(int n)', '{', '    if(n > 1)', '    {',
+      \ '        return fact(n-1) * n;', '    }', '    return 1;', '}', '', 'int main(int argc, char **argv)',
+      \ '{', '    frobnitz(fact(10));', '}'],
+      \ ['#include <stdio.h>', '', 'int fib(int n)', '{', '    if(n > 2)', '    {',
+      \ '        return fib(n-1) + fib(n-2);', '    }', '    return 1;', '}', '', '// Frobs foo heartily',
+      \ 'int frobnitz(int foo)', '{', '    int i;', '    for(i = 0; i < 10; i++)', '    {',
+      \ '        printf("%d\n", foo);', '    }', '}', '',
+      \ 'int main(int argc, char **argv)', '{', '    frobnitz(fib(10));', '}'])
+  call term_sendkeys(buf, ":diffupdate!\<cr>")
+  call term_sendkeys(buf, ":set diffopt+=internal\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_07', {})
+
+  call term_sendkeys(buf, ":set diffopt+=algorithm:patience\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_08', {})
+
+  call term_sendkeys(buf, ":set diffopt+=algorithm:histogram\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_09', {})
+
+  " Test 10-11: with/without indent-heuristic
+  call term_sendkeys(buf, ":set diffopt&mnv\<cr>")
+  call WriteDiffFiles(buf, ['', '  def finalize(values)', '', '    values.each do |v|', '      v.finalize', '    end'],
+      \ ['', '  def finalize(values)', '', '    values.each do |v|', '      v.prepare', '    end', '',
+      \ '    values.each do |v|', '      v.finalize', '    end'])
+  call term_sendkeys(buf, ":diffupdate!\<cr>")
+  call term_sendkeys(buf, ":set diffopt+=internal\<cr>:\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_11', {})
+
+  " Leave trailing : at commandline!
+  call term_sendkeys(buf, ":set diffopt-=indent-heuristic\<cr>:\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_10', {}, 'one')
+  " shouldn't matter, if indent-algorithm comes before or after the algorithm
+  call term_sendkeys(buf, ":set diffopt&\<cr>")
+  call term_sendkeys(buf, ":set diffopt+=indent-heuristic,algorithm:patience\<cr>:\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_11', {}, 'two')
+  call term_sendkeys(buf, ":set diffopt&\<cr>")
+  call term_sendkeys(buf, ":set diffopt+=algorithm:patience,indent-heuristic\<cr>:\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_11', {}, 'three')
+
+  " Test 12: diff the same file
+  call WriteDiffFiles(buf, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
+  call VerifyBoth(buf, 'Test_diff_12', '')
+
+  " Test 13: diff an empty file
+  call WriteDiffFiles(buf, [], [])
+  call VerifyBoth(buf, 'Test_diff_13', '')
+
+  " Test 14: test diffopt+=icase
+  call WriteDiffFiles(buf, ['a', 'b', 'cd'], ['A', 'b', 'cDe'])
+  call VerifyBoth(buf, 'Test_diff_14', " diffopt+=filler diffopt+=icase")
+
+  " Test 15-16: test diffopt+=iwhite
+  call WriteDiffFiles(buf, ['int main()', '{', '   printf("Hello, World!");', '   return 0;', '}'],
+      \ ['int main()', '{', '   if (0)', '   {', '      printf("Hello, World!");', '      return 0;', '   }', '}'])
+  call term_sendkeys(buf, ":diffupdate!\<cr>")
+  call term_sendkeys(buf, ":set diffopt&mnv diffopt+=filler diffopt+=iwhite\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_15', {})
+  call term_sendkeys(buf, ":set diffopt+=internal\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_16', {})
+
+  " Test 17: test diffopt+=iblank
+  call WriteDiffFiles(buf, ['a', ' ', 'cd', 'ef', 'xxx'], ['a', 'cd', '', 'ef', 'yyy'])
+  call VerifyInternal(buf, 'Test_diff_17', " diffopt+=iblank")
+
+  " Test 18: test diffopt+=iblank,iwhite / iwhiteall / iwhiteeol
+  call VerifyInternal(buf, 'Test_diff_18', " diffopt+=iblank,iwhite")
+  call VerifyInternal(buf, 'Test_diff_18', " diffopt+=iblank,iwhiteall")
+  call VerifyInternal(buf, 'Test_diff_18', " diffopt+=iblank,iwhiteeol")
+
+  " Test 19: test diffopt+=iwhiteeol
+  call WriteDiffFiles(buf, ['a ', 'x', 'cd', 'ef', 'xx  xx', 'foo', 'bar'], ['a', 'x', 'c d', ' ef', 'xx xx', 'foo', '', 'bar'])
+  call VerifyInternal(buf, 'Test_diff_19', " diffopt+=iwhiteeol")
+
+  " Test 20: test diffopt+=iwhiteall
+  call VerifyInternal(buf, 'Test_diff_20', " diffopt+=iwhiteall")
+
+  " Test 21: Delete all lines
+  call WriteDiffFiles(buf, [0], [])
+  call VerifyBoth(buf, "Test_diff_21", "")
+
+  " Test 22: Add line to empty file
+  call WriteDiffFiles(buf, [], [0])
+  call VerifyBoth(buf, "Test_diff_22", "")
+
+  call WriteDiffFiles(buf, ['?a', '?b', '?c'], ['!b'])
+  call VerifyInternal(buf, 'Test_diff_23', " diffopt+=linematch:30")
+
+  call WriteDiffFiles(buf, ['',
+      \ 'common line',
+      \ 'common line',
+      \ '',
+      \ 'DEFabc',
+      \ 'xyz',
+      \ 'xyz',
+      \ 'xyz',
+      \ 'DEFabc',
+      \ 'DEFabc',
+      \ 'DEFabc',
+      \ 'common line',
+      \ 'common line',
+      \ 'DEF',
+      \ 'common line',
+      \ 'DEF',
+      \ 'something' ],
+      \ ['',
+      \ 'common line',
+      \ 'common line',
+      \ '',
+      \ 'ABCabc',
+      \ 'ABCabc',
+      \ 'ABCabc',
+      \ 'ABCabc',
+      \ 'common line',
+      \ 'common line',
+      \ 'common line',
+      \ 'something'])
+  call VerifyInternal(buf, 'Test_diff_24', " diffopt+=linematch:30")
+
+
+  " clean up
+  call StopMNVInTerminal(buf)
+  call delete('Xdifile1')
+  call delete('Xdifile2')
+endfunc
+
+func Test_diff_with_scroll_and_change()
+  CheckScreendump
+
+  let lines =<< trim END
+	call setline(1, range(1, 15))
+	vnew
+	call setline(1, range(9, 15))
+	windo diffthis
+	wincmd h
+	exe "normal Gl5\<C-E>"
+  END
+  call writefile(lines, 'Xtest_scroll_change', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_scroll_change', {})
+
+  call VerifyScreenDump(buf, 'Test_diff_scroll_change_01', {})
+
+  call term_sendkeys(buf, "ax\<Esc>")
+  call VerifyScreenDump(buf, 'Test_diff_scroll_change_02', {})
+
+  call term_sendkeys(buf, "\<C-W>lay\<Esc>")
+  call VerifyScreenDump(buf, 'Test_diff_scroll_change_03', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_with_cursorline()
+  CheckScreendump
+
+  call writefile([
+	\ 'hi CursorLine ctermbg=red ctermfg=white',
+	\ 'set cursorline',
+	\ 'call setline(1, ["foo","foo","foo","bar"])',
+	\ 'vnew',
+	\ 'call setline(1, ["bee","foo","foo","baz"])',
+	\ 'windo diffthis',
+	\ '2wincmd w',
+	\ ], 'Xtest_diff_cursorline', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_cursorline', {})
+
+  call VerifyScreenDump(buf, 'Test_diff_with_cursorline_01', {})
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_with_cursorline_02', {})
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_with_cursorline_03', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_with_cursorline_number()
+  CheckScreendump
+
+  let lines =<< trim END
+      hi CursorLine ctermbg=red ctermfg=white
+      hi CursorLineNr ctermbg=white ctermfg=black cterm=underline
+      set cursorline number
+      call setline(1, ["baz", "foo", "foo", "bar"])
+      2
+      vnew
+      call setline(1, ["foo", "foo", "bar"])
+      windo diffthis
+      1wincmd w
+  END
+  call writefile(lines, 'Xtest_diff_cursorline_number', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_cursorline_number', {})
+
+  call VerifyScreenDump(buf, 'Test_diff_with_cursorline_number_01', {})
+  call term_sendkeys(buf, ":set cursorlineopt=number\r")
+  call VerifyScreenDump(buf, 'Test_diff_with_cursorline_number_02', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_with_cursorline_breakindent()
+  CheckScreendump
+
+  let lines =<< trim END
+    hi CursorLine ctermbg=red ctermfg=white
+    set noequalalways wrap diffopt=followwrap cursorline breakindent
+    50vnew
+    call setline(1, ['  ', '  ', '  ', '  '])
+    exe "norm! 20Afoo\<Esc>j20Afoo\<Esc>j20Afoo\<Esc>j20Abar\<Esc>"
+    vnew
+    call setline(1, ['  ', '  ', '  ', '  '])
+    exe "norm! 20Abee\<Esc>j20Afoo\<Esc>j20Afoo\<Esc>j20Abaz\<Esc>"
+    windo diffthis
+    2wincmd w
+  END
+  call writefile(lines, 'Xtest_diff_cursorline_breakindent', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_cursorline_breakindent', {})
+
+  call term_sendkeys(buf, "gg0")
+  call VerifyScreenDump(buf, 'Test_diff_with_cul_bri_01', {})
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_with_cul_bri_02', {})
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_with_cul_bri_03', {})
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_with_cul_bri_04', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_breakindent_after_filler()
+  CheckScreendump
+
+  let lines =<< trim END
+    set laststatus=0 diffopt+=followwrap breakindent breakindentopt=min:0
+    call setline(1, ['a', '  ' .. repeat('c', 50)])
+    vnew
+    call setline(1, ['a', 'b', '  ' .. repeat('c', 50)])
+    windo diffthis
+    norm! G$
+  END
+  call writefile(lines, 'Xtest_diff_breakindent_after_filler', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_breakindent_after_filler', #{rows: 8, cols: 45})
+  call VerifyScreenDump(buf, 'Test_diff_breakindent_after_filler', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_with_syntax()
+  CheckScreendump
+
+  let lines =<< trim END
+	void doNothing() {
+	   int x = 0;
+	   char *s = "hello";
+	   return 5;
+	}
+  END
+  call writefile(lines, 'Xprogram1.c', 'D')
+  let lines =<< trim END
+	void doSomething() {
+	   int x = 0;
+	   char *s = "there";
+	   return 5;
+	}
+  END
+  call writefile(lines, 'Xprogram2.c', 'D')
+
+  let lines =<< trim END
+    set diffopt=internal,filler
+	edit Xprogram1.c
+	diffsplit Xprogram2.c
+  END
+  call writefile(lines, 'Xtest_diff_syntax', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_syntax', {})
+
+  call VerifyScreenDump(buf, 'Test_diff_syntax_1', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_of_diff()
+  CheckScreendump
+  CheckFeature rightleft
+
+  call writefile([
+	\ 'call setline(1, ["aa","bb","cc","@@ -3,2 +5,7 @@","dd","ee","ff"])',
+	\ 'vnew',
+	\ 'call setline(1, ["aa","bb","cc"])',
+	\ 'windo diffthis',
+	\ '1wincmd w',
+	\ 'setlocal number',
+	\ ], 'Xtest_diff_diff', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_diff', {})
+
+  call VerifyScreenDump(buf, 'Test_diff_of_diff_01', {})
+
+  call term_sendkeys(buf, ":set rightleft\<cr>")
+  call VerifyScreenDump(buf, 'Test_diff_of_diff_02', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func CloseoffSetup()
+  enew
+  call setline(1, ['one', 'two', 'three'])
+  diffthis
+  new
+  call setline(1, ['one', 'tow', 'three'])
+  diffthis
+  call assert_equal(1, &diff)
+  bw!
+endfunc
+
+func Test_diff_closeoff()
+  " "closeoff" included by default: last diff win gets 'diff' reset'
+  call CloseoffSetup()
+  call assert_equal(0, &diff)
+  enew!
+
+  " "closeoff" excluded: last diff win keeps 'diff' set'
+  set diffopt-=closeoff
+  call CloseoffSetup()
+  call assert_equal(1, &diff)
+  diffoff!
+  enew!
+endfunc
+
+func Test_diff_followwrap()
+  new
+  set diffopt+=followwrap
+  set wrap
+  diffthis
+  call assert_equal(1, &wrap)
+  diffoff
+  set nowrap
+  diffthis
+  call assert_equal(0, &wrap)
+  diffoff
+  set diffopt&
+  bwipe!
+endfunc
+
+func Test_diff_maintains_change_mark()
+  func DiffMaintainsChangeMark()
+    enew!
+    call setline(1, ['a', 'b', 'c', 'd'])
+    diffthis
+    new
+    call setline(1, ['a', 'b', 'c', 'e'])
+    " Set '[ and '] marks
+    2,3yank
+    call assert_equal([2, 3], [line("'["), line("']")])
+    " Verify they aren't affected by the implicit diff
+    diffthis
+    call assert_equal([2, 3], [line("'["), line("']")])
+    " Verify they aren't affected by an explicit diff
+    diffupdate
+    call assert_equal([2, 3], [line("'["), line("']")])
+    bwipe!
+    bwipe!
+  endfunc
+
+  set diffopt-=internal
+  call DiffMaintainsChangeMark()
+  set diffopt+=internal
+  call DiffMaintainsChangeMark()
+
+  set diffopt&
+  delfunc DiffMaintainsChangeMark
+endfunc
+
+" Test for 'patchexpr'
+func Test_patchexpr()
+  let g:patch_args = []
+  func TPatch()
+    call add(g:patch_args, readfile(v:fname_in))
+    call add(g:patch_args, readfile(v:fname_diff))
+    call writefile(['output file'], v:fname_out)
+  endfunc
+  set patchexpr=TPatch()
+
+  call writefile(['input file'], 'Xinput', 'D')
+  call writefile(['diff file'], 'Xdiff', 'D')
+  %bwipe!
+  edit Xinput
+  diffpatch Xdiff
+  call assert_equal('output file', getline(1))
+  call assert_equal('Xinput.new', bufname())
+  call assert_equal(2, winnr('$'))
+  call assert_true(&diff)
+
+  " Using a script-local function
+  func s:NewPatchExpr()
+  endfunc
+  set patchexpr=s:NewPatchExpr()
+  call assert_equal(expand('<SID>') .. 'NewPatchExpr()', &patchexpr)
+  set patchexpr=<SID>NewPatchExpr()
+  call assert_equal(expand('<SID>') .. 'NewPatchExpr()', &patchexpr)
+
+  set patchexpr&
+  delfunc TPatch
+  delfunc s:NewPatchExpr
+  %bwipe!
+endfunc
+
+func Test_diff_rnu()
+  CheckScreendump
+
+  let content =<< trim END
+    set diffopt=internal,filler
+    call setline(1, ['a', 'a', 'a', 'y', 'b', 'b', 'b', 'b', 'b'])
+    vnew
+    call setline(1, ['a', 'a', 'a', 'x', 'x', 'x', 'b', 'b', 'b', 'b', 'b'])
+    windo diffthis
+    setlocal number rnu foldcolumn=0
+  END
+  call writefile(content, 'Xtest_diff_rnu', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_rnu', {})
+
+  call VerifyScreenDump(buf, 'Test_diff_rnu_01', {})
+
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_rnu_02', {})
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_rnu_03', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_multilineconceal()
+  new
+  diffthis
+
+  new
+  call matchadd('Conceal', 'a\nb', 9, -1, {'conceal': 'Y'})
+  set cole=2 cocu=n
+  call setline(1, ["a", "b"])
+  diffthis
+  redraw
+endfunc
+
+func Test_diff_and_scroll()
+  " this was causing an ml_get error
+  set ls=2
+  for i in range(winheight(0) * 2)
+    call setline(i, i < winheight(0) - 10 ? i : i + 10)
+  endfor
+  vnew
+  for i in range(winheight(0)*2 + 10)
+    call setline(i, i < winheight(0) - 10 ? 0 : i)
+  endfor
+  diffthis
+  wincmd p
+  diffthis
+  execute 'normal ' . winheight(0) . "\<C-d>"
+
+  bwipe!
+  bwipe!
+  set ls&
+endfunc
+
+func Test_diff_filler_cursorcolumn()
+  CheckScreendump
+
+  let content =<< trim END
+    call setline(1, ['aa', 'bb', 'cc'])
+    vnew
+    call setline(1, ['aa', 'cc'])
+    windo diffthis
+    wincmd p
+    setlocal cursorcolumn foldcolumn=0
+    norm! gg0
+    redraw!
+  END
+  call writefile(content, 'Xtest_diff_cuc', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_cuc', {})
+
+  call VerifyScreenDump(buf, 'Test_diff_cuc_01', {})
+
+  call term_sendkeys(buf, "l")
+  call term_sendkeys(buf, "\<C-l>")
+  call VerifyScreenDump(buf, 'Test_diff_cuc_02', {})
+  call term_sendkeys(buf, "0j")
+  call term_sendkeys(buf, "\<C-l>")
+  call VerifyScreenDump(buf, 'Test_diff_cuc_03', {})
+  call term_sendkeys(buf, "l")
+  call term_sendkeys(buf, "\<C-l>")
+  call VerifyScreenDump(buf, 'Test_diff_cuc_04', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+" Test for adding/removing lines inside diff chunks, between diff chunks
+" and before diff chunks
+func Test_diff_modify_chunks()
+  set diffopt=internal,filler
+  enew!
+  let w2_id = win_getid()
+  call setline(1, ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'])
+  new
+  let w1_id = win_getid()
+  call setline(1, ['a', '2', '3', 'd', 'e', 'f', '7', '8', 'i'])
+  windo diffthis
+
+  " remove a line between two diff chunks and create a new diff chunk
+  call win_gotoid(w2_id)
+  5d
+  call win_gotoid(w1_id)
+  call diff_hlID(5, 1)->synIDattr('name')->assert_equal('DiffAdd')
+
+  " add a line between two diff chunks
+  call win_gotoid(w2_id)
+  normal! 4Goe
+  call win_gotoid(w1_id)
+  call diff_hlID(4, 1)->synIDattr('name')->assert_equal('')
+  call diff_hlID(5, 1)->synIDattr('name')->assert_equal('')
+
+  " remove all the lines in a diff chunk.
+  call win_gotoid(w2_id)
+  7,8d
+  call win_gotoid(w1_id)
+  let hl = range(1, 9)->map({_, lnum -> diff_hlID(lnum, 1)->synIDattr('name')})
+  call assert_equal(['', 'DiffText', 'DiffText', '', '', '', 'DiffAdd',
+        \ 'DiffAdd', ''], hl)
+
+  " remove lines from one diff chunk to just before the next diff chunk
+  call win_gotoid(w2_id)
+  call setline(1, ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'])
+  2,6d
+  call win_gotoid(w1_id)
+  let hl = range(1, 9)->map({_, lnum -> diff_hlID(lnum, 1)->synIDattr('name')})
+  call assert_equal(['', 'DiffText', 'DiffText', 'DiffAdd', 'DiffAdd',
+        \ 'DiffAdd', 'DiffAdd', 'DiffAdd', ''], hl)
+
+  " remove lines just before the top of a diff chunk
+  call win_gotoid(w2_id)
+  call setline(1, ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'])
+  5,6d
+  call win_gotoid(w1_id)
+  let hl = range(1, 9)->map({_, lnum -> diff_hlID(lnum, 1)->synIDattr('name')})
+  call assert_equal(['', 'DiffText', 'DiffText', '', 'DiffText', 'DiffText',
+        \ 'DiffAdd', 'DiffAdd', ''], hl)
+
+  " remove line after the end of a diff chunk
+  call win_gotoid(w2_id)
+  call setline(1, ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'])
+  4d
+  call win_gotoid(w1_id)
+  let hl = range(1, 9)->map({_, lnum -> diff_hlID(lnum, 1)->synIDattr('name')})
+  call assert_equal(['', 'DiffText', 'DiffText', 'DiffAdd', '', '', 'DiffText',
+        \ 'DiffText', ''], hl)
+
+  " remove lines starting from the end of one diff chunk and ending inside
+  " another diff chunk
+  call win_gotoid(w2_id)
+  call setline(1, ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'])
+  4,7d
+  call win_gotoid(w1_id)
+  let hl = range(1, 9)->map({_, lnum -> diff_hlID(lnum, 1)->synIDattr('name')})
+  call assert_equal(['', 'DiffText', 'DiffText', 'DiffText', 'DiffAdd',
+        \ 'DiffAdd', 'DiffAdd', 'DiffAdd', ''], hl)
+
+  " removing the only remaining diff chunk should make the files equal
+  call win_gotoid(w2_id)
+  call setline(1, ['a', '2', '3', 'x', 'd', 'e', 'f', 'x', '7', '8', 'i'])
+  8d
+  let hl = range(1, 10)->map({_, lnum -> diff_hlID(lnum, 1)->synIDattr('name')})
+  call assert_equal(['', '', '', 'DiffAdd', '', '', '', '', '', ''], hl)
+  call win_gotoid(w2_id)
+  4d
+  call win_gotoid(w1_id)
+  let hl = range(1, 9)->map({_, lnum -> diff_hlID(lnum, 1)->synIDattr('name')})
+  call assert_equal(['', '', '', '', '', '', '', '', ''], hl)
+
+  %bw!
+  set diffopt&
+endfunc
+
+func Test_diff_binary()
+  CheckScreendump
+
+  let content =<< trim END
+    call setline(1, ['a', 'b', "c\n", 'd', 'e', 'f', 'g'])
+    vnew
+    call setline(1, ['A', 'b', 'c', 'd', 'E', 'f', 'g'])
+    windo diffthis
+    wincmd p
+    norm! gg0
+    redraw!
+  END
+  call writefile(content, 'Xtest_diff_bin', 'D')
+  let buf = RunMNVInTerminal('-S Xtest_diff_bin', {})
+
+  " Test using internal diff
+  call VerifyScreenDump(buf, 'Test_diff_bin_01', {})
+
+  " Test using internal diff and case folding
+  call term_sendkeys(buf, ":set diffopt+=icase\<cr>")
+  call term_sendkeys(buf, "\<C-l>")
+  call VerifyScreenDump(buf, 'Test_diff_bin_02', {})
+  " Test using external diff
+  call term_sendkeys(buf, ":set diffopt=filler\<cr>")
+  call term_sendkeys(buf, "\<C-l>")
+  call VerifyScreenDump(buf, 'Test_diff_bin_03', {})
+  " Test using external diff and case folding
+  call term_sendkeys(buf, ":set diffopt=filler,icase\<cr>")
+  call term_sendkeys(buf, "\<C-l>")
+  call VerifyScreenDump(buf, 'Test_diff_bin_04', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+  set diffopt&mnv
+endfunc
+
+" Test for using the 'zi' command to invert 'foldenable' in diff windows (test
+" for the issue fixed by patch 6.2.317)
+func Test_diff_foldinvert()
+  %bw!
+  edit Xdoffile1
+  new Xdoffile2
+  new Xdoffile3
+  windo diffthis
+  " open a non-diff window
+  botright new
+  1wincmd w
+  call assert_true(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_true(getwinvar(3, '&foldenable'))
+  normal zi
+  call assert_false(getwinvar(1, '&foldenable'))
+  call assert_false(getwinvar(2, '&foldenable'))
+  call assert_false(getwinvar(3, '&foldenable'))
+  normal zi
+  call assert_true(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_true(getwinvar(3, '&foldenable'))
+
+  " If the current window has 'noscrollbind', then 'zi' should not change
+  " 'foldenable' in other windows.
+  1wincmd w
+  set noscrollbind
+  normal zi
+  call assert_false(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_true(getwinvar(3, '&foldenable'))
+
+  " 'zi' should not change the 'foldenable' for windows with 'noscrollbind'
+  1wincmd w
+  set scrollbind
+  normal zi
+  call setwinvar(2, '&scrollbind', v:false)
+  normal zi
+  call assert_false(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_false(getwinvar(3, '&foldenable'))
+
+  %bw!
+  set scrollbind&
+endfunc
+
+" This was scrolling for 'cursorbind' but 'scrollbind' is more important
+func Test_diff_scroll()
+  CheckScreendump
+
+  let left =<< trim END
+      line 1
+      line 2
+      line 3
+      line 4
+
+      // Common block
+      // one
+      // containing
+      // four lines
+
+      // Common block
+      // two
+      // containing
+      // four lines
+  END
+  call writefile(left, 'Xleft', 'D')
+  let right =<< trim END
+      line 1
+      line 2
+      line 3
+      line 4
+
+      Lorem
+      ipsum
+      dolor
+      sit
+      amet,
+      consectetur
+      adipiscing
+      elit.
+      Etiam
+      luctus
+      lectus
+      sodales,
+      dictum
+
+      // Common block
+      // one
+      // containing
+      // four lines
+
+      Vestibulum
+      tincidunt
+      aliquet
+      nulla.
+
+      // Common block
+      // two
+      // containing
+      // four lines
+  END
+  call writefile(right, 'Xright', 'D')
+  let buf = RunMNVInTerminal('-d Xleft Xright', {'rows': 12})
+  call term_sendkeys(buf, "\<C-W>\<C-W>jjjj")
+  call VerifyScreenDump(buf, 'Test_diff_scroll_1', {})
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_diff_scroll_2', {})
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+" This was scrolling too many lines.
+func Test_diff_scroll_wrap_on()
+  20new
+  40vsplit
+  call setline(1, map(range(1, 9), 'repeat(v:val, 200)'))
+  setlocal number diff so=0
+  redraw
+  normal! jj
+  call assert_equal(1, winsaveview().topline)
+  normal! j
+  call assert_equal(2, winsaveview().topline)
+
+  bwipe!
+  bwipe!
+endfunc
+
+func Test_diff_scroll_many_filler()
+  20new
+  vnew
+  call setline(1, range(1, 40))
+  diffthis
+  setlocal scrolloff=0
+  wincmd p
+  call setline(1, range(1, 20)->reverse() + ['###']->repeat(41) + range(21, 40)->reverse())
+  diffthis
+  setlocal scrolloff=0
+  wincmd p
+  redraw
+
+  " Note: need a redraw after each scroll, otherwise the test always passes.
+  for _ in range(2)
+    normal! G
+    redraw
+    call assert_equal(40, winsaveview().topline)
+    call assert_equal(19, winsaveview().topfill)
+    exe "normal! \<C-B>"
+    redraw
+    call assert_equal(22, winsaveview().topline)
+    call assert_equal(0, winsaveview().topfill)
+    exe "normal! \<C-B>"
+    redraw
+    call assert_equal(4, winsaveview().topline)
+    call assert_equal(0, winsaveview().topfill)
+    exe "normal! \<C-B>"
+    redraw
+    call assert_equal(1, winsaveview().topline)
+    call assert_equal(0, winsaveview().topfill)
+    set smoothscroll
+  endfor
+
+  set smoothscroll&
+  %bwipe!
+endfunc
+
+" This was trying to update diffs for a buffer being closed
+func Test_diff_only()
+  silent! lfile
+  set diff
+  lopen
+  norm o
+  silent! norm o
+
+  set nodiff
+  %bwipe!
+endfunc
+
+" This was causing invalid diff block values
+" FIXME: somehow this causes a valgrind error when run directly but not when
+" run as a test.
+func Test_diff_manipulations()
+  set diff
+  split 0
+  sil! norm R
doobdeuR
doobdeuR
doobdeu
+
+  set nodiff
+  %bwipe!
+endfunc
+
+" This was causing the line number in the diff block to go below one.
+" FIXME: somehow this causes a valgrind error when run directly but not when
+" run as a test.
+func Test_diff_put_and_undo()
+  set diff
+  next 0
+  split 00
+  sil! norm o0gguudpo0ggJuudp
+
+  bwipe!
+  bwipe!
+  set nodiff
+endfunc
+
+" Test for the diff() function
+def Test_diff_func()
+  # string is added/removed/modified at the beginning
+  assert_equal("@@ -0,0 +1 @@\n+abc\n",
+               diff(['def'], ['abc', 'def'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 0, to_idx: 0, to_count: 1}],
+               diff(['def'], ['abc', 'def'], {output: 'indices'}))
+  assert_equal("@@ -1 +0,0 @@\n-abc\n",
+               diff(['abc', 'def'], ['def'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 0}],
+               diff(['abc', 'def'], ['def'], {output: 'indices'}))
+  assert_equal("@@ -1 +1 @@\n-abc\n+abx\n",
+               diff(['abc', 'def'], ['abx', 'def'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+               diff(['abc', 'def'], ['abx', 'def'], {output: 'indices'}))
+
+  # string is added/removed/modified at the end
+  assert_equal("@@ -1,0 +2 @@\n+def\n",
+               diff(['abc'], ['abc', 'def'], {output: 'unified'}))
+  assert_equal([{from_idx: 1, from_count: 0, to_idx: 1, to_count: 1}],
+               diff(['abc'], ['abc', 'def'], {output: 'indices'}))
+  assert_equal("@@ -2 +1,0 @@\n-def\n",
+               diff(['abc', 'def'], ['abc'], {output: 'unified'}))
+  assert_equal([{from_idx: 1, from_count: 1, to_idx: 1, to_count: 0}],
+               diff(['abc', 'def'], ['abc'], {output: 'indices'}))
+  assert_equal("@@ -2 +2 @@\n-def\n+xef\n",
+               diff(['abc', 'def'], ['abc', 'xef'], {output: 'unified'}))
+  assert_equal([{from_idx: 1, from_count: 1, to_idx: 1, to_count: 1}],
+               diff(['abc', 'def'], ['abc', 'xef'], {output: 'indices'}))
+
+  # string is added/removed/modified in the middle
+  assert_equal("@@ -2,0 +3 @@\n+xxx\n",
+               diff(['111', '222', '333'], ['111', '222', 'xxx', '333'], {output: 'unified'}))
+  assert_equal([{from_idx: 2, from_count: 0, to_idx: 2, to_count: 1}],
+               diff(['111', '222', '333'], ['111', '222', 'xxx', '333'], {output: 'indices'}))
+  assert_equal("@@ -3 +2,0 @@\n-333\n",
+               diff(['111', '222', '333', '444'], ['111', '222', '444'], {output: 'unified'}))
+  assert_equal([{from_idx: 2, from_count: 1, to_idx: 2, to_count: 0}],
+               diff(['111', '222', '333', '444'], ['111', '222', '444'], {output: 'indices'}))
+  assert_equal("@@ -3 +3 @@\n-333\n+xxx\n",
+               diff(['111', '222', '333', '444'], ['111', '222', 'xxx', '444'], {output: 'unified'}))
+  assert_equal([{from_idx: 2, from_count: 1, to_idx: 2, to_count: 1}],
+               diff(['111', '222', '333', '444'], ['111', '222', 'xxx', '444'], {output: 'indices'}))
+
+  # new strings are added to an empty List
+  assert_equal("@@ -0,0 +1,2 @@\n+abc\n+def\n",
+               diff([], ['abc', 'def'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 0, to_idx: 0, to_count: 2}],
+               diff([], ['abc', 'def'], {output: 'indices'}))
+
+  # all the strings are removed from a List
+  assert_equal("@@ -1,2 +0,0 @@\n-abc\n-def\n",
+               diff(['abc', 'def'], [], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 2, to_idx: 0, to_count: 0}],
+               diff(['abc', 'def'], [], {output: 'indices'}))
+
+  # First character is added/removed/different
+  assert_equal("@@ -1 +1 @@\n-abc\n+bc\n",
+               diff(['abc'], ['bc'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+               diff(['abc'], ['bc'], {output: 'indices'}))
+  assert_equal("@@ -1 +1 @@\n-bc\n+abc\n",
+               diff(['bc'], ['abc'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+               diff(['bc'], ['abc'], {output: 'indices'}))
+  assert_equal("@@ -1 +1 @@\n-abc\n+xbc\n",
+               diff(['abc'], ['xbc'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+               diff(['abc'], ['xbc'], {output: 'indices'}))
+
+  # Last character is added/removed/different
+  assert_equal("@@ -1 +1 @@\n-abc\n+abcd\n",
+               diff(['abc'], ['abcd'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+               diff(['abc'], ['abcd'], {output: 'indices'}))
+  assert_equal("@@ -1 +1 @@\n-abcd\n+abc\n",
+               diff(['abcd'], ['abc'], {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+               diff(['abcd'], ['abc'], {output: 'indices'}))
+  var diff_unified: string = diff(['abc'], ['abx'], {output: 'unified'})
+  assert_equal("@@ -1 +1 @@\n-abc\n+abx\n", diff_unified)
+  var diff_indices: list<dict<number>> =
+    diff(['abc'], ['abx'], {output: 'indices'})
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+               diff_indices)
+
+  # partial string modification at the start and at the end.
+  var fromlist =<< trim END
+    one two
+    three four
+    five six
+  END
+  var tolist =<< trim END
+    one
+    six
+  END
+  assert_equal("@@ -1,3 +1,2 @@\n-one two\n-three four\n-five six\n+one\n+six\n", diff(fromlist, tolist, {output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 3, to_idx: 0, to_count: 2}],
+               diff(fromlist, tolist, {output: 'indices'}))
+
+  # non-contiguous modifications
+  fromlist =<< trim END
+    one two
+    three four
+    five abc six
+  END
+  tolist =<< trim END
+    one abc two
+    three four
+    five six
+  END
+  assert_equal("@@ -1 +1 @@\n-one two\n+one abc two\n@@ -3 +3 @@\n-five abc six\n+five six\n",
+               diff(fromlist, tolist, {output: 'unified'}))
+  assert_equal([{'from_count': 1, 'to_idx': 0, 'to_count': 1, 'from_idx': 0},
+                {'from_count': 1, 'to_idx': 2, 'to_count': 1, 'from_idx': 2}],
+               diff(fromlist, tolist, {output: 'indices'}))
+
+  # add/remove blank lines
+  assert_equal("@@ -2,2 +1,0 @@\n-\n-\n",
+               diff(['one', '', '', 'two'], ['one', 'two'], {output: 'unified'}))
+  assert_equal([{from_idx: 1, from_count: 2, to_idx: 1, to_count: 0}],
+               diff(['one', '', '', 'two'], ['one', 'two'], {output: 'indices'}))
+  assert_equal("@@ -1,0 +2,2 @@\n+\n+\n",
+               diff(['one', 'two'], ['one', '', '', 'two'], {output: 'unified'}))
+  assert_equal([{'from_idx': 1, 'from_count': 0, 'to_idx': 1, 'to_count': 2}],
+               diff(['one', 'two'], ['one', '', '', 'two'], {output: 'indices'}))
+
+  # diff ignoring case
+  assert_equal('', diff(['abc', 'def'], ['ABC', 'DEF'], {icase: true, output: 'unified'}))
+  assert_equal([], diff(['abc', 'def'], ['ABC', 'DEF'], {icase: true, output: 'indices'}))
+
+  # diff ignoring all whitespace changes except leading whitespace changes
+  assert_equal('', diff(['abc def'], ['abc  def '], {iwhite: true}))
+  assert_equal("@@ -1 +1 @@\n- abc\n+  xxx\n", diff([' abc'], ['  xxx'], {iwhite: v:true}))
+  assert_equal("@@ -1 +1 @@\n- abc\n+  xxx\n", diff([' abc'], ['  xxx'], {iwhite: v:false}))
+  assert_equal("@@ -1 +1 @@\n-abc \n+xxx  \n", diff(['abc '], ['xxx  '], {iwhite: v:true}))
+  assert_equal("@@ -1 +1 @@\n-abc \n+xxx  \n", diff(['abc '], ['xxx  '], {iwhite: v:false}))
+
+  # diff ignoring all whitespace changes
+  assert_equal('', diff(['abc def'], [' abc  def '], {iwhiteall: true}))
+  assert_equal("@@ -1 +1 @@\n- abc \n+  xxx  \n", diff([' abc '], ['  xxx  '], {iwhiteall: v:true}))
+  assert_equal("@@ -1 +1 @@\n- abc \n+  xxx  \n", diff([' abc '], ['  xxx  '], {iwhiteall: v:false}))
+
+  # diff ignoring trailing whitespace changes
+  assert_equal('', diff(['abc'], ['abc  '], {iwhiteeol: true}))
+
+  # diff ignoring blank lines
+  assert_equal('', diff(['one', '', '', 'two'], ['one', 'two'], {iblank: true}))
+  assert_equal('', diff(['one', 'two'], ['one', '', '', 'two'], {iblank: true}))
+
+  # same string
+  assert_equal('', diff(['abc', 'def', 'ghi'], ['abc', 'def', 'ghi']))
+  assert_equal('', diff([''], ['']))
+  assert_equal('', diff([], []))
+
+  # different xdiff algorithms
+  for algo in ['myers', 'minimal', 'patience', 'histogram']
+    assert_equal("@@ -1 +1 @@\n- abc \n+  xxx  \n",
+      diff([' abc '], ['  xxx  '], {algorithm: algo, output: 'unified'}))
+    assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+      diff([' abc '], ['  xxx  '], {algorithm: algo, output: 'indices'}))
+  endfor
+  assert_equal("@@ -1 +1 @@\n- abc \n+  xxx  \n",
+    diff([' abc '], ['  xxx  '], {indent-heuristic: true, output: 'unified'}))
+  assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
+    diff([' abc '], ['  xxx  '], {indent-heuristic: true, output: 'indices'}))
+
+  # identical strings
+  assert_equal('', diff(['111', '222'], ['111', '222'], {output: 'unified'}))
+  assert_equal([], diff(['111', '222'], ['111', '222'], {output: 'indices'}))
+  assert_equal('', diff([], [], {output: 'unified'}))
+  assert_equal([], diff([], [], {output: 'indices'}))
+
+  # If 'diffexpr' is set, it should not be used for diff()
+  def MyDiffExpr()
+  enddef
+  var save_diffexpr = &diffexpr
+  :set diffexpr=MyDiffExpr()
+  assert_equal("@@ -1 +1 @@\n-abc\n+\n",
+               diff(['abc'], [''], {output: 'unified'}))
+  assert_equal([{'from_idx': 0, 'from_count': 1, 'to_idx': 0, 'to_count': 1}],
+               diff(['abc'], [''], {output: 'indices'}))
+  assert_equal('MyDiffExpr()', &diffexpr)
+  &diffexpr = save_diffexpr
+
+  # try different values for unified diff 'context'
+  assert_equal("@@ -0,0 +1 @@\n+x\n",
+               diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c']))
+  assert_equal("@@ -0,0 +1 @@\n+x\n",
+               diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: 0}))
+  assert_equal("@@ -1 +1,2 @@\n+x\n a\n",
+               diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: 1}))
+  assert_equal("@@ -1,2 +1,3 @@\n+x\n a\n b\n",
+               diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: 2}))
+  assert_equal("@@ -1,3 +1,4 @@\n+x\n a\n b\n c\n",
+               diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: 3}))
+  assert_equal("@@ -1,3 +1,4 @@\n+x\n a\n b\n c\n",
+               diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: 4}))
+  assert_equal("@@ -0,0 +1 @@\n+x\n",
+               diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: -1}))
+
+  # Error cases
+  assert_fails('call diff({}, ["a"])', 'E1211:')
+  assert_fails('call diff(["a"], {})', 'E1211:')
+  assert_fails('call diff(["a"], ["a"], [])', 'E1206:')
+  assert_fails('call diff(["a"], ["a"], {output: "xyz"})', 'E106: Unsupported diff output format: xyz')
+  assert_fails('call diff(["a"], ["a"], {context: []})', 'E745: Using a List as a Number')
+enddef
+
+" Test for using the diff() function with 'diffexpr'
+func Test_diffexpr_with_diff_func()
+  CheckScreendump
+
+  let lines =<< trim END
+    def DiffFuncExpr()
+      var in: list<string> = readfile(v:fname_in)
+      var new: list<string> = readfile(v:fname_new)
+      var out: string = diff(in, new)
+      writefile(split(out, "\n"), v:fname_out)
+    enddef
+    set diffexpr=DiffFuncExpr()
+
+    edit Xdifffunc1.txt
+    diffthis
+    vert split Xdifffunc2.txt
+    diffthis
+  END
+  call writefile(lines, 'XsetupDiffFunc.mnv', 'D')
+
+  call writefile(['zero', 'one', 'two', 'three'], 'Xdifffunc1.txt', 'D')
+  call writefile(['one', 'twox', 'three', 'four'], 'Xdifffunc2.txt', 'D')
+
+  let buf = RunMNVInTerminal('-S XsetupDiffFunc.mnv', {'rows': 12})
+  call VerifyScreenDump(buf, 'Test_difffunc_diffexpr_1', {})
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_toggle_wrap_skipcol_leftcol()
+  61vnew
+  call setline(1, 'Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.')
+  30vnew
+  call setline(1, 'ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.')
+  let win1 = win_getid()
+  setlocal smoothscroll
+  exe "normal! $\<C-E>"
+  wincmd l
+  let win2 = win_getid()
+  setlocal smoothscroll
+  exe "normal! $\<C-E>"
+  call assert_equal([
+        \ '<<<sadipscing elitr, sed diam |<<<tetur sadipscing elitr, sed|',
+        \ 'nonumy eirmod tempor invidunt | diam nonumy eirmod tempor inv|',
+        \ 'ut labore et dolore magna aliq|idunt ut labore et dolore magn|',
+        \ 'uyam erat, sed diam voluptua. |a aliquyam erat, sed diam volu|',
+        \ '~                             |ptua.                         |',
+        \ ], ScreenLines([1, 5], 62))
+  call assert_equal({'col': 29, 'row': 4, 'endcol': 29, 'curscol': 29},
+        \ screenpos(win1, line('.', win1), col('.', win1)))
+  call assert_equal({'col': 36, 'row': 5, 'endcol': 36, 'curscol': 36},
+        \ screenpos(win2, line('.', win2), col('.', win2)))
+
+  wincmd h
+  diffthis
+  wincmd l
+  diffthis
+  normal! 0
+  call assert_equal([
+        \ '  ipsum dolor sit amet, conset|  Lorem ipsum dolor sit amet, |',
+        \ '~                             |~                             |',
+        \ ], ScreenLines([1, 2], 62))
+  call assert_equal({'col': 3, 'row': 1, 'endcol': 3, 'curscol': 3},
+        \ screenpos(win1, line('.', win1), col('.', win1)))
+  call assert_equal({'col': 34, 'row': 1, 'endcol': 34, 'curscol': 34},
+        \ screenpos(win2, line('.', win2), col('.', win2)))
+
+  normal! $
+  call assert_equal([
+        \ '  voluptua.                   |   diam voluptua.             |',
+        \ '~                             |~                             |',
+        \ ], ScreenLines([1, 2], 62))
+  call assert_equal({'col': 11, 'row': 1, 'endcol': 11, 'curscol': 11},
+        \ screenpos(win1, line('.', win1), col('.', win1)))
+  call assert_equal({'col': 48, 'row': 1, 'endcol': 48, 'curscol': 48},
+        \ screenpos(win2, line('.', win2), col('.', win2)))
+
+  diffoff!
+  call assert_equal([
+        \ 'ipsum dolor sit amet, consetet|Lorem ipsum dolor sit amet, co|',
+        \ 'ur sadipscing elitr, sed diam |nsetetur sadipscing elitr, sed|',
+        \ 'nonumy eirmod tempor invidunt | diam nonumy eirmod tempor inv|',
+        \ 'ut labore et dolore magna aliq|idunt ut labore et dolore magn|',
+        \ 'uyam erat, sed diam voluptua. |a aliquyam erat, sed diam volu|',
+        \ '~                             |ptua.                         |',
+        \ ], ScreenLines([1, 6], 62))
+  call assert_equal({'col': 29, 'row': 5, 'endcol': 29, 'curscol': 29},
+        \ screenpos(win1, line('.', win1), col('.', win1)))
+  call assert_equal({'col': 36, 'row': 6, 'endcol': 36, 'curscol': 36},
+        \ screenpos(win2, line('.', win2), col('.', win2)))
+
+  bwipe!
+  bwipe!
+endfunc
+
+" Ctrl-D reveals filler lines below the last line in the buffer.
+func Test_diff_eob_halfpage()
+  new
+  call setline(1, ['']->repeat(10) + ['a'])
+  diffthis
+  new
+  call setline(1, ['']->repeat(3) + ['a', 'b'])
+  diffthis
+  resize 5
+  wincmd j
+  resize 5
+  norm G
+  call assert_equal(7, line('w0'))
+  exe "norm! \<C-D>"
+  call assert_equal(8, line('w0'))
+
+  %bwipe!
+endfunc
+
+func Test_diff_overlapped_diff_blocks_will_be_merged()
+  CheckScreendump
+
+  let lines =<< trim END
+    func DiffExprStub()
+      let txt_in = readfile(v:fname_in)
+      let txt_new = readfile(v:fname_new)
+      if txt_in == ["line1"] && txt_new == ["line2"]
+        call writefile(["1c1"], v:fname_out)
+      elseif txt_in == readfile("Xdiin1") && txt_new == readfile("Xdinew1")
+        call writefile(readfile("Xdiout1"), v:fname_out)
+      elseif txt_in == readfile("Xdiin2") && txt_new == readfile("Xdinew2")
+        call writefile(readfile("Xdiout2"), v:fname_out)
+      endif
+    endfunc
+  END
+  call writefile(lines, 'XdiffSetup', 'D')
+
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d -S XdiffSetup Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  call WriteDiffFiles(buf, ["a", "b"], ["x", "x"])
+  call writefile(["a", "b"], "Xdiin1")
+  call writefile(["x", "x"], "Xdinew1")
+  call writefile(["1c1", "2c2"], "Xdiout1")
+  call term_sendkeys(buf, ":set diffexpr=DiffExprStub()\<CR>:")
+  call VerifyBoth(buf, "Test_diff_overlapped_2.01", "")
+  call term_sendkeys(buf, ":set diffexpr&\<CR>:")
+
+  call WriteDiffFiles(buf, ["a", "b", "c"], ["x", "c"])
+  call writefile(["a", "b", "c"], "Xdiin1")
+  call writefile(["x", "c"], "Xdinew1")
+  call writefile(["1c1", "2d1"], "Xdiout1")
+  call term_sendkeys(buf, ":set diffexpr=DiffExprStub()\<CR>:")
+  call VerifyBoth(buf, "Test_diff_overlapped_2.02", "")
+  call term_sendkeys(buf, ":set diffexpr&\<CR>:")
+
+  call WriteDiffFiles(buf, ["a", "c"], ["x", "x", "c"])
+  call writefile(["a", "c"], "Xdiin1")
+  call writefile(["x", "x", "c"], "Xdinew1")
+  call writefile(["1c1", "1a2"], "Xdiout1")
+  call term_sendkeys(buf, ":set diffexpr=DiffExprStub()\<CR>:")
+  call VerifyBoth(buf, "Test_diff_overlapped_2.03", "")
+  call term_sendkeys(buf, ":set diffexpr&\<CR>:")
+
+  call StopMNVInTerminal(buf)
+  wincmd c
+
+  call WriteDiffFiles3(0, [], [], [])
+  let buf = RunMNVInTerminal('-d -S XdiffSetup Xdifile1 Xdifile2 Xdifile3', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["y", "b", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.01", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["a", "y", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.02", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["a", "b", "y"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.03", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["y", "y", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.04", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["a", "y", "y"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.05", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["y", "y", "y"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.06", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "x"], ["y", "y", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.07", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["x", "x", "c"], ["a", "y", "y"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.08", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["y", "y", "y", "d", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.09", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["y", "y", "y", "y", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.10", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["y", "y", "y", "y", "y"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.11", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "y", "y", "d", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.12", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "y", "y", "y", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.13", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "y", "y", "y", "y"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.14", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "b", "y", "d", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.15", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "b", "y", "y", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.16", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "b", "y", "y", "y"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.17", "")
+
+  call WriteDiffFiles3(buf, ["a", "b"], ["x", "b"], ["y", "y"])
+  call writefile(["a", "b"], "Xdiin1")
+  call writefile(["x", "b"], "Xdinew1")
+  call writefile(["1c1"], "Xdiout1")
+  call writefile(["a", "b"], "Xdiin2")
+  call writefile(["y", "y"], "Xdinew2")
+  call writefile(["1c1", "2c2"], "Xdiout2")
+  call term_sendkeys(buf, ":set diffexpr=DiffExprStub()\<CR>:")
+  call VerifyInternal(buf, "Test_diff_overlapped_3.18", "")
+  call term_sendkeys(buf, ":set diffexpr&\<CR>:")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d"], ["x", "b", "x", "d"], ["y", "y", "c", "d"])
+  call writefile(["a", "b", "c", "d"], "Xdiin1")
+  call writefile(["x", "b", "x", "d"], "Xdinew1")
+  call writefile(["1c1", "3c3"], "Xdiout1")
+  call writefile(["a", "b", "c", "d"], "Xdiin2")
+  call writefile(["y", "y", "c", "d"], "Xdinew2")
+  call writefile(["1c1", "2c2"], "Xdiout2")
+  call term_sendkeys(buf, ":set diffexpr=DiffExprStub()\<CR>:")
+  call VerifyInternal(buf, "Test_diff_overlapped_3.19", "")
+  call term_sendkeys(buf, ":set diffexpr&\<CR>:")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d"], ["x", "b", "x", "d"], ["y", "y", "y", "d"])
+  call writefile(["a", "b", "c", "d"], "Xdiin1")
+  call writefile(["x", "b", "x", "d"], "Xdinew1")
+  call writefile(["1c1", "3c3"], "Xdiout1")
+  call writefile(["a", "b", "c", "d"], "Xdiin2")
+  call writefile(["y", "y", "y", "d"], "Xdinew2")
+  call writefile(["1c1", "2,3c2,3"], "Xdiout2")
+  call term_sendkeys(buf, ":set diffexpr=DiffExprStub()\<CR>:")
+  call VerifyInternal(buf, "Test_diff_overlapped_3.20", "")
+  call term_sendkeys(buf, ":set diffexpr&\<CR>:")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d"], ["x", "b", "x", "d"], ["y", "y", "y", "y"])
+  call writefile(["a", "b", "c", "d"], "Xdiin1")
+  call writefile(["x", "b", "x", "d"], "Xdinew1")
+  call writefile(["1c1", "3c3"], "Xdiout1")
+  call writefile(["a", "b", "c", "d"], "Xdiin2")
+  call writefile(["y", "y", "y", "y"], "Xdinew2")
+  call writefile(["1c1", "2,4c2,4"], "Xdiout2")
+  call term_sendkeys(buf, ":set diffexpr=DiffExprStub()\<CR>:")
+  call VerifyInternal(buf, "Test_diff_overlapped_3.21", "")
+  call term_sendkeys(buf, ":set diffexpr&\<CR>:")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["b", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.22", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.23", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], [])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.24", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["a", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.25", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["a"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.26", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["b"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.27", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["d", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.28", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.29", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "d", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.30", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.31", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.32", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "b", "d", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.33", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "b", "e"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.34", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c", "d", "e"], ["a", "x", "c", "x", "e"], ["a", "b"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.35", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["a", "y", "b", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.36", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["a", "x", "c"], ["a", "b", "y", "c"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.37", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["d", "e"], ["b", "f"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.38", "")
+
+  call WriteDiffFiles3(buf, ["a", "b", "c"], ["d", "e"], ["b"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.39", "")
+
+  " File 3 overlaps twice, 2nd overlap completely within the existing block.
+  call WriteDiffFiles3(buf, ["foo", "a", "b", "c", "bar"], ["foo", "w", "x", "y", "z", "bar"], ["foo", "1", "a", "b", "2", "bar"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.40", "")
+
+  " File 3 overlaps twice, 2nd overlap extends beyond existing block on new
+  " side. Make sure we don't over-extend the range and hit 'bar'.
+  call WriteDiffFiles3(buf, ["foo", "a", "b", "c", "d", "bar"], ["foo", "w", "x", "y", "z", "u", "bar"], ["foo", "1", "a", "b", "2", "d", "bar"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.41", "")
+
+  " Chained overlaps. File 3's 2nd overlap spans two diff blocks and is longer
+  " than the 2nd one.
+  call WriteDiffFiles3(buf, ["foo", "a", "b", "c", "d", "e", "f", "bar"], ["foo", "w", "x", "y", "z", "e", "u", "bar"], ["foo", "1", "b", "2", "3", "d", "4", "f", "bar"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.42", "")
+
+  " File 3 has 2 overlaps. An add and a delete. First overlap's expansion hits
+  " the 2nd one. Make sure we adjust the diff block to have fewer lines.
+  call WriteDiffFiles3(buf, ["foo", "a", "b", "bar"], ["foo", "x", "y", "bar"], ["foo", "1", "a", "bar"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.43", "")
+
+  " File 3 has 2 overlaps. An add and another add. First overlap's expansion hits
+  " the 2nd one. Make sure we adjust the diff block to have more lines.
+  call WriteDiffFiles3(buf, ["foo", "a", "b", "c", "d", "bar"], ["foo", "w", "x", "y", "z", "u", "bar"], ["foo", "1", "a", "b", "3", "4", "d", "bar"])
+  call VerifyBoth(buf, "Test_diff_overlapped_3.44", "")
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+" switching windows in diff mode caused an unnecessary scroll
+func Test_diff_topline_noscroll()
+  CheckScreendump
+
+  let content =<< trim END
+    call setline(1, range(1,60))
+    vnew
+    call setline(1, range(1,10) + range(50,60))
+    windo diffthis
+    norm! G
+    exe "norm! 30\<C-y>"
+  END
+  call writefile(content, 'Xcontent', 'D')
+  let buf = RunMNVInTerminal('-S Xcontent', {'rows': 20})
+  call VerifyScreenDump(buf, 'Test_diff_topline_1', {})
+  call term_sendkeys(buf, ":echo line('w0', 1001)\<cr>")
+  call term_wait(buf)
+  call VerifyScreenDump(buf, 'Test_diff_topline_2', {})
+  call term_sendkeys(buf, "\<C-W>p")
+  call term_wait(buf)
+  call VerifyScreenDump(buf, 'Test_diff_topline_3', {})
+  call term_sendkeys(buf, "\<C-W>p")
+  call term_wait(buf)
+  call VerifyScreenDump(buf, 'Test_diff_topline_4', {})
+  call StopMNVInTerminal(buf)
+endfunc
+
+" Test inline highlighting which shows what's different within each diff block
+func Test_diff_inline()
+  CheckScreendump
+
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  call WriteDiffFiles(buf, ["abcdef ghi jk n", "x", "y"], ["aBcef gHi lm n", "y", "z"])
+  call VerifyInternal(buf, "Test_diff_inline_01", "")
+  call VerifyInternal(buf, "Test_diff_inline_02", " diffopt+=inline:none")
+
+  " inline:simple is the same as default
+  call VerifyInternal(buf, "Test_diff_inline_01", " diffopt+=inline:simple")
+
+  call VerifyInternal(buf, "Test_diff_inline_03", " diffopt+=inline:char")
+  call VerifyInternal(buf, "Test_diff_inline_04", " diffopt+=inline:word")
+
+  " multiple inline values will the last one
+  call VerifyInternal(buf, "Test_diff_inline_01", " diffopt+=inline:none,inline:char,inline:simple")
+  call VerifyInternal(buf, "Test_diff_inline_02", " diffopt+=inline:simple,inline:word,inline:none")
+  call VerifyInternal(buf, "Test_diff_inline_03", " diffopt+=inline:simple,inline:word,inline:char")
+
+  " DiffTextAdd highlight
+  call term_sendkeys(buf, ":hi DiffTextAdd ctermbg=blue\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_05", " diffopt+=inline:char")
+
+  " Live update in insert mode
+  call term_sendkeys(buf, "\<Esc>isometext")
+  call VerifyScreenDump(buf, "Test_diff_inline_06", {})
+  call term_sendkeys(buf, "\<Esc>u")
+
+  " icase simple scenarios
+  call VerifyInternal(buf, "Test_diff_inline_07", " diffopt+=inline:simple,icase")
+  call VerifyInternal(buf, "Test_diff_inline_08", " diffopt+=inline:char,icase")
+  call VerifyInternal(buf, "Test_diff_inline_09", " diffopt+=inline:word,icase")
+
+  " diff algorithms should affect highlight
+  call WriteDiffFiles(buf, ["apples and oranges"], ["oranges and apples"])
+  call VerifyInternal(buf, "Test_diff_inline_10", " diffopt+=inline:char")
+  call VerifyInternal(buf, "Test_diff_inline_11", " diffopt+=inline:char,algorithm:patience")
+
+  " icase: composing chars and Unicode fold case edge cases
+  call WriteDiffFiles(buf,
+        \ ["1 - sigma in 6σ and Ὀδυσσεύς", "1 - angstrom in åå", "1 - composing: ii⃗I⃗"],
+        \ ["2 - Sigma in 6Σ and ὈΔΥΣΣΕΎΣ", "2 - Angstrom in ÅÅ", "2 - Composing: i⃗I⃗I⃗"])
+  call VerifyInternal(buf, "Test_diff_inline_12", " diffopt+=inline:char")
+  call VerifyInternal(buf, "Test_diff_inline_13", " diffopt+=inline:char,icase")
+
+  " wide chars
+  call WriteDiffFiles(buf, ["abc😅xde一", "f🚀g"], ["abcy😢de", "二f🚀g"])
+  call VerifyInternal(buf, "Test_diff_inline_14", " diffopt+=inline:char,icase")
+
+  " NUL char (\n below is internally substituted as NUL)
+  call WriteDiffFiles(buf, ["1\n34\n5\n6"], ["1234\n5", "6"])
+  call VerifyInternal(buf, "Test_diff_inline_15", " diffopt+=inline:char")
+
+  " word diff: always use first buffer's iskeyword and ignore others' for consistency
+  call WriteDiffFiles(buf, ["foo+bar test"], ["foo+baz test"])
+  call VerifyInternal(buf, "Test_diff_inline_word_01", " diffopt+=inline:word")
+
+  call term_sendkeys(buf, ":set iskeyword+=+\<CR>:diffupdate\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_word_02", " diffopt+=inline:word")
+
+  call term_sendkeys(buf, ":set iskeyword&\<CR>:wincmd w\<CR>")
+  call term_sendkeys(buf, ":set iskeyword+=+\<CR>:wincmd w\<CR>:diffupdate\<CR>")
+  " Use the previous screen dump as 2nd buffer's iskeyword does not matter
+  call VerifyInternal(buf, "Test_diff_inline_word_01", " diffopt+=inline:word")
+
+  call term_sendkeys(buf, ":windo set iskeyword&\<CR>:1wincmd w\<CR>")
+
+  " word diff: test handling of multi-byte characters. Only alphanumeric chars
+  " (e.g. Greek alphabet, but not CJK/emoji) count as words.
+  call WriteDiffFiles(buf, ["🚀⛵️一二三ひらがなΔέλτα Δelta foobar"], ["🚀🛸一二四ひらなδέλτα δelta foobar"])
+  call VerifyInternal(buf, "Test_diff_inline_word_03", " diffopt+=inline:word")
+
+  " char diff: should slide highlight to whitespace boundary if possible for
+  " better readability (by using forced indent-heuristics). A wrong result
+  " would be if the highlight is "Bar, prefix". It should be "prefixBar, "
+  " instead.
+  call WriteDiffFiles(buf, ["prefixFoo, prefixEnd"], ["prefixFoo, prefixBar, prefixEnd"])
+  call VerifyInternal(buf, "Test_diff_inline_char_01", " diffopt+=inline:char")
+
+  " char diff: small gaps between inline diff blocks will be merged during refine step
+  " - first segment: test that we iteratively merge small gaps after we merged
+  "   adjacent blocks, but only with limited number (set to 4) of iterations.
+  " - second and third segments: show that we need a large enough adjacent block to
+  "   trigger a merge.
+  " - fourth segment: small gaps are not merged when adjacent large block is
+  "   on a different line.
+  call WriteDiffFiles(buf,
+        \ ["abcdefghijklmno", "anchor1",
+        \  "abcdefghijklmno", "anchor2",
+        \  "abcdefghijklmno", "anchor3",
+        \  "test", "multiline"],
+        \ ["a?c?e?g?i?k???o", "anchor1",
+        \  "a??de?????klmno", "anchor2",
+        \  "a??de??????lmno", "anchor3",
+        \  "t?s?", "??????i?e"])
+  call VerifyInternal(buf, "Test_diff_inline_char_02", " diffopt+=inline:char")
+
+  " Test multi-line blocks and whitespace
+  call WriteDiffFiles(buf,
+        \ ["this   is   ", "sometest text foo", "baz abc def ", "one", "word another word", "additional line"],
+        \ ["this is some test", "texts", "foo bar abX Yef     ", "oneword another word"])
+  call VerifyInternal(buf, "Test_diff_inline_multiline_01", " diffopt+=inline:char,iwhite")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_02", " diffopt+=inline:word,iwhite")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_03", " diffopt+=inline:char,iwhiteeol")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_04", " diffopt+=inline:word,iwhiteeol")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_05", " diffopt+=inline:char,iwhiteall")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_06", " diffopt+=inline:word,iwhiteall")
+
+  " newline should be highlighted too when 'list' is set
+  call term_sendkeys(buf, ":windo set list\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_07", " diffopt+=inline:char")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_08", " diffopt+=inline:char,iwhite")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_09", " diffopt+=inline:char,iwhiteeol")
+  call VerifyInternal(buf, "Test_diff_inline_multiline_10", " diffopt+=inline:char,iwhiteall")
+  call term_sendkeys(buf, ":windo set nolist\<CR>")
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diff_inline_multibuffer()
+  CheckScreendump
+
+  call WriteDiffFiles3(0, [], [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2 Xdifile3', {})
+  call term_sendkeys(buf, ":windo set autoread\<CR>:1wincmd w\<CR>")
+  call term_sendkeys(buf, ":hi DiffTextAdd ctermbg=blue\<CR>")
+
+  call WriteDiffFiles3(buf,
+        \ ["That is buffer1.", "anchor", "Some random text", "anchor"],
+        \ ["This is buffer2.", "anchor", "Some text", "anchor", "buffer2/3"],
+        \ ["This is buffer3. Last.", "anchor", "Some more", "text here.", "anchor", "only in buffer2/3", "not in buffer1"])
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_01", " diffopt+=inline:char")
+
+  " Close one of the buffers and make sure it updates correctly
+  call term_sendkeys(buf, ":diffoff\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_02", " diffopt+=inline:char")
+
+  " Update text in the non-diff buffer and nothing should be changed
+  call term_sendkeys(buf, "\<Esc>isometext")
+  call VerifyScreenDump(buf, "Test_diff_inline_multibuffer_03", {})
+  call term_sendkeys(buf, "\<Esc>u")
+
+  call term_sendkeys(buf, ":diffthis\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_01", " diffopt+=inline:char")
+
+  " Test that removing first buffer from diff will in turn use the next
+  " earliest buffer's iskeyword during word diff.
+  call WriteDiffFiles3(buf,
+        \ ["This+is=a-setence"],
+        \ ["This+is=another-setence"],
+        \ ["That+is=a-setence"])
+  call term_sendkeys(buf, ":set iskeyword+=+\<CR>:2wincmd w\<CR>:set iskeyword+=-\<CR>:1wincmd w\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_04", " diffopt+=inline:word")
+  call term_sendkeys(buf, ":diffoff\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_05", " diffopt+=inline:word")
+  call term_sendkeys(buf, ":diffthis\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_04", " diffopt+=inline:word")
+
+  " Test multi-buffer char diff refinement, and that removing a buffer from
+  " diff will update the others properly.
+  call WriteDiffFiles3(buf,
+        \ ["abcdefghijkYmYYY"],
+        \ ["aXXdXXghijklmnop"],
+        \ ["abcdefghijkYmYop"])
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_06", " diffopt+=inline:char")
+  call term_sendkeys(buf, ":diffoff\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_07", " diffopt+=inline:char")
+  call term_sendkeys(buf, ":diffthis\<CR>")
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_06", " diffopt+=inline:char")
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+" Test that when using multi-buffer diff, an empty block would be correctly
+" skipped in the result, without resulting in invalid states or crashes.
+func Test_diff_inline_multibuffer_empty_block()
+  CheckScreendump
+
+  call writefile(['anchor1', '1234567890abcde', 'anchor2'], 'Xdifile1')
+  call writefile(['anchor1', '1234567--0abc-e', 'anchor2'], 'Xdifile2')
+  call writefile(['anchor1', 'anchor2'], 'Xdifile3')
+  call writefile(['anchor1', '1???????90abcd?', 'anchor2'], 'Xdifile4')
+
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2 Xdifile3 Xdifile4', {})
+  call VerifyInternal(buf, "Test_diff_inline_multibuffer_empty_block_01", " diffopt+=inline:char")
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diffget_diffput_linematch()
+  CheckScreendump
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  " enable linematch
+  call term_sendkeys(buf, ":set diffopt+=linematch:30\<CR>")
+  call WriteDiffFiles(buf, ['',
+      \ 'common line',
+      \ 'common line',
+      \ '',
+      \ 'ABCabc',
+      \ 'ABCabc',
+      \ 'ABCabc',
+      \ 'ABCabc',
+      \ 'common line',
+      \ 'common line',
+      \ 'common line',
+      \ 'something' ],
+      \ ['',
+      \ 'common line',
+      \ 'common line',
+      \ '',
+      \ 'DEFabc',
+      \ 'xyz',
+      \ 'xyz',
+      \ 'xyz',
+      \ 'DEFabc',
+      \ 'DEFabc',
+      \ 'DEFabc',
+      \ 'common line',
+      \ 'common line',
+      \ 'DEF',
+      \ 'common line',
+      \ 'DEF',
+      \ 'something'])
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_1', {})
+
+  " get from window 1 from line 5 to 9
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, ":5,9diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_2', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get from window 2 from line 5 to 10
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, ":5,10diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_3', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get all from window 2
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, ":4,17diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_4', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get all from window 1
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, ":4,12diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_5', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get from window 1 using do 1 line 5
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "5gg")
+  call term_sendkeys(buf, ":diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_6', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get from window 1 using do 2 line 6
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "6gg")
+  call term_sendkeys(buf, ":diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_7', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get from window 1 using do 2 line 7
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "7gg")
+  call term_sendkeys(buf, ":diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_8', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get from window 1 using do 2 line 11
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "11gg")
+  call term_sendkeys(buf, ":diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_9', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " get from window 1 using do 2 line 12
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "12gg")
+  call term_sendkeys(buf, ":diffget\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_10', {})
+
+  " undo the last diffget
+  call term_sendkeys(buf, "u")
+
+  " put from window 1 using dp 1 line 5
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "5gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_11', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 1 using dp 2 line 6
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "6gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_12', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 1 using dp 2 line 7
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "7gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_13', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 1 using dp 2 line 11
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "11gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_14', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 1 using dp 2 line 12
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "12gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_15', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 2 using dp line 6
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "6gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_16', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 2 using dp line 8
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "8gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_17', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 2 using dp line 9
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "9gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_18', {})
+
+  " undo the last diffput
+  call term_sendkeys(buf, "1\<c-w>w")
+  call term_sendkeys(buf, "u")
+
+  " put from window 2 using dp line 17
+  call term_sendkeys(buf, "2\<c-w>w")
+  call term_sendkeys(buf, "17gg")
+  call term_sendkeys(buf, ":diffput\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_get_put_linematch_19', {})
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_linematch_diff()
+  CheckScreendump
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  " enable linematch
+  call term_sendkeys(buf, ":set diffopt=internal,filler,linematch:30\<CR>")
+  call WriteDiffFiles(buf, ['// abc d?',
+      \ '// d?',
+      \ '// d?' ],
+      \ ['!',
+      \ 'abc d!',
+      \ 'd!'])
+  call term_sendkeys(buf, ":\<CR>") " clear cmdline
+  call VerifyScreenDump(buf, 'Test_linematch_diff1', {})
+
+  " test that filler is always implicitly set by linematch
+  call term_sendkeys(buf, ":set diffopt-=filler\<CR>")
+  call term_sendkeys(buf, ":\<CR>") " clear cmdline
+  call VerifyScreenDump(buf, 'Test_linematch_diff1', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_linematch_diff_iwhite()
+  CheckScreendump
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  " setup a diff with 2 files and set linematch:30, with ignore white
+  call term_sendkeys(buf, ":set diffopt=internal,filler,linematch:30\<CR>")
+  call WriteDiffFiles(buf, ['void testFunction () {',
+      \ '  for (int i = 0; i < 10; i++) {',
+      \ '    for (int j = 0; j < 10; j++) {',
+      \ '    }',
+      \ '  }',
+      \ '}' ],
+      \ ['void testFunction () {',
+      \ '  // for (int j = 0; j < 10; i++) {',
+      \ '  // }',
+      \ '}'])
+  call VerifyScreenDump(buf, 'Test_linematch_diff_iwhite1', {})
+  call term_sendkeys(buf, ":set diffopt+=iwhiteall\<CR>")
+  call VerifyScreenDump(buf, 'Test_linematch_diff_iwhite2', {})
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_linematch_diff_grouping()
+  CheckScreendump
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  " a diff that would result in multiple groups before grouping optimization
+  call term_sendkeys(buf, ":set diffopt=internal,filler,linematch:30\<CR>")
+  call WriteDiffFiles(buf, ['!A',
+      \ '!B',
+      \ '!C' ],
+      \ ['?Z',
+      \ '?A',
+      \ '?B',
+      \ '?C',
+      \ '?A',
+      \ '?B',
+      \ '?B',
+      \ '?C'])
+  call VerifyScreenDump(buf, 'Test_linematch_diff_grouping1', {})
+  call WriteDiffFiles(buf, ['!A',
+      \ '!B',
+      \ '!C' ],
+      \ ['?A',
+      \ '?Z',
+      \ '?B',
+      \ '?C',
+      \ '?A',
+      \ '?B',
+      \ '?C',
+      \ '?C'])
+  call VerifyScreenDump(buf, 'Test_linematch_diff_grouping2', {})
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_linematch_diff_scroll()
+  CheckScreendump
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  " a diff that would result in multiple groups before grouping optimization
+  call term_sendkeys(buf, ":set diffopt=internal,filler,linematch:30\<CR>")
+  call WriteDiffFiles(buf, ['!A',
+      \ '!B',
+      \ '!C' ],
+      \ ['?A',
+      \ '?Z',
+      \ '?B',
+      \ '?C',
+      \ '?A',
+      \ '?B',
+      \ '?C',
+      \ '?C'])
+  " scroll down to show calculation of top fill and scroll to correct line in
+  " both windows
+  call VerifyScreenDump(buf, 'Test_linematch_diff_grouping_scroll0', {})
+  call term_sendkeys(buf, "3\<c-e>")
+  call VerifyScreenDump(buf, 'Test_linematch_diff_grouping_scroll1', {})
+  call term_sendkeys(buf, "3\<c-e>")
+  call VerifyScreenDump(buf, 'Test_linematch_diff_grouping_scroll2', {})
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_linematch_line_limit_exceeded()
+  CheckScreendump
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+  call WriteDiffFiles(0, [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+  call term_sendkeys(buf, ":set autoread\<CR>\<c-w>w:set autoread\<CR>\<c-w>w")
+
+  call term_sendkeys(buf, ":set diffopt=internal,filler,linematch:10\<CR>")
+  " a diff block will not be aligned with linematch because it's contents
+  " exceed 10 lines
+  call WriteDiffFiles(buf,
+        \ ['common line',
+        \ 'HIL',
+        \ '',
+        \ 'aABCabc',
+        \ 'aABCabc',
+        \ 'aABCabc',
+        \ 'aABCabc',
+        \ 'common line',
+        \ 'HIL',
+        \ 'common line',
+        \ 'something'],
+        \ ['common line',
+        \ 'DEF',
+        \ 'GHI',
+        \ 'something',
+        \ '',
+        \ 'aDEFabc',
+        \ 'xyz',
+        \ 'xyz',
+        \ 'xyz',
+        \ 'aDEFabc',
+        \ 'aDEFabc',
+        \ 'aDEFabc',
+        \ 'common line',
+        \ 'DEF',
+        \ 'GHI',
+        \ 'something else',
+        \ 'common line',
+        \ 'something'])
+  call VerifyScreenDump(buf, 'Test_linematch_line_limit_exceeded1', {})
+  " after increasing the count to 30, the limit is not exceeded, and the
+  " alignment algorithm will run on the largest diff block here
+  call term_sendkeys(buf, ":set diffopt+=linematch:30\<CR>")
+  call VerifyScreenDump(buf, 'Test_linematch_line_limit_exceeded2', {})
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_linematch_3diffs()
+  CheckScreendump
+  call delete('.Xdifile1.swp')
+  call delete('.Xdifile2.swp')
+  call delete('.Xdifile3.swp')
+  call WriteDiffFiles3(0, [], [], [])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2 Xdifile3', {})
+  call term_sendkeys(buf, "1\<c-w>w:set autoread\<CR>")
+  call term_sendkeys(buf, "2\<c-w>w:set autoread\<CR>")
+  call term_sendkeys(buf, "3\<c-w>w:set autoread\<CR>")
+  call term_sendkeys(buf, ":set diffopt=internal,filler,linematch:30\<CR>")
+  call WriteDiffFiles3(buf,
+        \ ["",
+        \ "  common line",
+        \ "      AAA",
+        \ "      AAA",
+        \ "      AAA"],
+        \ ["",
+        \ "  common line",
+        \ "  <<<<<<< HEAD",
+        \ "      AAA",
+        \ "      AAA",
+        \ "      AAA",
+        \ "  =======",
+        \ "      BBB",
+        \ "      BBB",
+        \ "      BBB",
+        \ "  >>>>>>> branch1"],
+        \ ["",
+        \ "  common line",
+        \ "      BBB",
+        \ "      BBB",
+        \ "      BBB"])
+  call VerifyScreenDump(buf, 'Test_linematch_3diffs1', {})
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+" this used to access invalid memory
+func Test_linematch_3diffs_sanity_check()
+  CheckScreendump
+  call delete('.Xfile_linematch1.swp')
+  call delete('.Xfile_linematch2.swp')
+  call delete('.Xfile_linematch3.swp')
+  let lines =<< trim END
+    set diffopt=internal,filler,linematch:60
+    call feedkeys("Aq\<esc>")
+    call feedkeys("GAklm\<esc>")
+    call feedkeys("o")
+  END
+  call writefile(lines, 'Xlinematch_3diffs.mnv', 'D')
+  call writefile(['abcd', 'def', 'hij'], 'Xfile_linematch1', 'D')
+  call writefile(['defq', 'hijk', 'nopq'], 'Xfile_linematch2', 'D')
+  call writefile(['hijklm', 'nopqr', 'stuv'], 'Xfile_linematch3', 'D')
+  call WriteDiffFiles3(0, [], [], [])
+  let buf = RunMNVInTerminal('-d -S Xlinematch_3diffs.mnv Xfile_linematch1 Xfile_linematch2 Xfile_linematch3', {})
+  call VerifyScreenDump(buf, 'Test_linematch_3diffs2', {})
+
+  " clean up
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diffanchors()
+  CheckScreendump
+  call WriteDiffFiles3(0,
+      \ ["anchorA1", "1", "2", "3",
+      \  "100", "101", "102", "anchorB", "103", "104", "105"],
+      \ ["100", "101", "102", "anchorB", "103", "104", "105",
+      \  "anchorA2", "1", "2", "3"],
+      \ ["100", "anchorB", "103",
+      \  "anchorA3", "1", "2", "3"])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2 Xdifile3', {})
+
+  " Simple diff without any anchors
+  call VerifyInternal(buf, "Test_diff_anchors_00", "")
+
+  " Setting diffopt+=anchor or diffanchors without the other won't do anything
+  call VerifyInternal(buf, "Test_diff_anchors_00", " diffopt+=anchor")
+  call VerifyInternal(buf, "Test_diff_anchors_00", " dia=1/anchorA/")
+
+  " Use a single anchor by specifying a pattern. Test both internal and
+  " external diff to make sure both paths work.
+  call VerifyBoth(buf, "Test_diff_anchors_01", " dia=1/anchorA/ diffopt+=anchor")
+
+  " Use 2 anchors. They should be sorted by line number, so in file 2/3
+  " anchorB is used before anchorA.
+  call VerifyBoth(buf, "Test_diff_anchors_02", " dia=1/anchorA/,1/anchorB/ diffopt+=anchor")
+
+  " Set marks and specify addresses using marks and repeat the test
+  call term_sendkeys(buf, ":2wincmd w\<CR>:1/anchorA/mark a\<CR>")
+  call term_sendkeys(buf, ":1/anchorB/mark b\<CR>")
+  call term_sendkeys(buf, ":3wincmd w\<CR>:1/anchorA/mark a\<CR>")
+  call term_sendkeys(buf, ":1/anchorB/mark b\<CR>")
+  call term_sendkeys(buf, ":1wincmd w\<CR>:1/anchorA/mark a\<CR>")
+  call term_sendkeys(buf, ":1/anchorB/mark b\<CR>")
+
+  call VerifyInternal(buf, "Test_diff_anchors_01", " dia='a diffopt+=anchor")
+  call VerifyInternal(buf, "Test_diff_anchors_02", " dia='a,'b diffopt+=anchor")
+
+  " Update marks to point somewhere else. When we first set the mark the diff
+  " won't be updated until we manually invoke :diffupdate.
+  call VerifyInternal(buf, "Test_diff_anchors_01", " dia='a diffopt+=anchor")
+  call term_sendkeys(buf, ":1wincmd w\<CR>:1/anchorB/mark a\<CR>:")
+  call term_wait(buf)
+  call VerifyScreenDump(buf, "Test_diff_anchors_01", {})
+  call term_sendkeys(buf, ":diffupdate\<CR>:")
+  call term_wait(buf)
+  call VerifyScreenDump(buf, "Test_diff_anchors_03", {})
+
+  " Use local diff anchors with line numbers, and repeat the same test
+  call term_sendkeys(buf, ":2wincmd w\<CR>:setlocal dia=8\<CR>")
+  call term_sendkeys(buf, ":3wincmd w\<CR>:setlocal dia=4\<CR>")
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=1\<CR>")
+  call VerifyInternal(buf, "Test_diff_anchors_01", " diffopt+=anchor")
+  call term_sendkeys(buf, ":2wincmd w\<CR>:setlocal dia=8,4\<CR>")
+  call term_sendkeys(buf, ":3wincmd w\<CR>:setlocal dia=4,2\<CR>")
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=1,8\<CR>")
+  call VerifyInternal(buf, "Test_diff_anchors_02", " diffopt+=anchor")
+
+  " Test multiple diff anchors on the same line in file 1.
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=1,1\<CR>")
+  call VerifyInternal(buf, "Test_diff_anchors_04", " diffopt+=anchor")
+
+  " Test that if one file has fewer diff anchors than others. MNV should only
+  " use the minimum in this case.
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=8\<CR>")
+  call VerifyInternal(buf, "Test_diff_anchors_05", " diffopt+=anchor")
+
+  " $+1 should anchor everything past the last line
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=$+1\<CR>")
+  call VerifyInternal(buf, "Test_diff_anchors_06", " diffopt+=anchor")
+
+  " Sorting of diff anchors should work with multiple anchors
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=1,10,8,2\<CR>")
+  call term_sendkeys(buf, ":2wincmd w\<CR>:setlocal dia=1,2,3,4\<CR>")
+  call term_sendkeys(buf, ":3wincmd w\<CR>:setlocal dia=4,3,2,1\<CR>")
+  call VerifyInternal(buf, "Test_diff_anchors_07", " diffopt+=anchor")
+
+  " Intentionally set an invalid anchor with wrong line number. Should fall
+  " back to treat it as if no anchors are used at all.
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=1,10,8,2,1000 | silent! diffupdate\<CR>:")
+  call VerifyScreenDump(buf, "Test_diff_anchors_00", {})
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+" Test that scrollbind and topline calculations work correctly, even when diff
+" anchors create adjacent diff blocks which complicates the calculations.
+func Test_diffanchors_scrollbind_topline()
+  CheckScreendump
+
+  " Simple overlapped line anchored to be adjacent to each other
+  call WriteDiffFiles(0,
+      \ ["anchor1", "diff1a", "anchor2"],
+      \ ["anchor1", "diff2a", "anchor2"])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2', {})
+
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=2\<CR>")
+  call term_sendkeys(buf, ":2wincmd w\<CR>:setlocal dia=3\<CR>")
+
+  call VerifyInternal(buf, "Test_diff_anchors_scrollbind_topline_01", " diffopt+=anchor")
+  call term_sendkeys(buf, "\<Esc>\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_02", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_03", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_04", {})
+
+  " Also test no-filler
+  call term_sendkeys(buf, "gg")
+  call VerifyInternal(buf, "Test_diff_anchors_scrollbind_topline_05", " diffopt+=anchor diffopt-=filler")
+  call term_sendkeys(buf, "\<Esc>\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_06", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_07", {})
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diffanchors_scrollbind_topline2()
+  CheckScreendump
+
+  " More-complicated case with 3 files and multiple overlapping diff blocks
+  call WriteDiffFiles3(0,
+      \ ["anchor1"],
+      \ ["diff2a", "diff2b", "diff2c", "diff2d", "anchor2"],
+      \ ["diff3a", "diff3c", "diff3d", "anchor3", "diff3e"])
+  let buf = RunMNVInTerminal('-d Xdifile1 Xdifile2 Xdifile3', {})
+
+  call term_sendkeys(buf, ":1wincmd w\<CR>:setlocal dia=1,1,2\<CR>")
+  call term_sendkeys(buf, ":2wincmd w\<CR>:setlocal dia=3,5,6\<CR>")
+  call term_sendkeys(buf, ":3wincmd w\<CR>:setlocal dia=2,4,5\<CR>")
+
+  call VerifyInternal(buf, "Test_diff_anchors_scrollbind_topline_08", " diffopt+=anchor")
+  call term_sendkeys(buf, ":1wincmd w\<CR>")
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_09", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_10", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_11", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_12", {})
+
+  " Also test no-filler
+  call term_sendkeys(buf, ":3wincmd w\<CR>gg")
+  call VerifyInternal(buf, "Test_diff_anchors_scrollbind_topline_13", " diffopt+=anchor diffopt-=filler")
+  call term_sendkeys(buf, "\<Esc>\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_14", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_15", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_16", {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, "Test_diff_anchors_scrollbind_topline_17", {})
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+" Test that setting 'diffanchors' will update the diff.
+func Test_diffanchors_option_set_update()
+  set diffanchors='a diffopt=internal,filler,anchor
+
+  " Set up 3 tabs that share some buffers, and set up marks on each of them.
+  " We want to make sure only relevant tabs are updated if buffer-local diff
+  " anchors are updated, but all tabs should refresh if global diff anchors
+  " are updated (see diffanchors_changed() in code).
+
+  " Tab 1. A buffer here will be reused.
+  call setline(1, range(1, 10))
+  3mark a
+  4mark b
+  diffthis
+  new
+  call setline(1, range(21, 25))
+  let buf = bufnr()
+  1mark a
+  2mark b
+  diffthis
+  call assert_equal(2, diff_filler(1))
+  call assert_equal(0, diff_filler(2))
+
+  " Tab 2. "buf" is here but intentionally not participating in diff.
+  tabnew
+  exec 'buf ' .. buf
+  diffoff
+  new
+  call setline(1, range(31, 40))
+  8mark a
+  9mark b
+  diffthis
+  new
+  call setline(1, range(41, 50))
+  5mark a
+  6mark b
+  diffthis
+
+  call assert_equal(3, diff_filler(5))
+  call assert_equal(0, diff_filler(6))
+  call assert_equal(0, diff_filler(7))
+
+  " Update mark a location, and check that the diff has *not* updated. When
+  " updating marks diff's won't automatically update.
+  7mark a
+  call assert_equal(3, diff_filler(5))
+  call assert_equal(0, diff_filler(6))
+  call assert_equal(0, diff_filler(7))
+
+  " Tab 3. "buf" is used here and also in a diff.
+  tabnew
+  call setline(1, range(51, 65))
+  10mark a
+  11mark b
+  diffthis
+  exec 'sbuffer ' .. buf
+  diffthis
+
+  " Change local diff anchor of "buf" to mark b
+  setlocal diffanchors='b
+
+  " Tab 1 should immediately update the diff to use mark b because the buf
+  " local diff anchor has been changed in "buf".
+  1tabnext
+  call assert_equal(0, diff_filler(1))
+  call assert_equal(1, diff_filler(2))
+
+  " Tab 2 should not immediately update because "buf" is not a diff buffer
+  " here.
+  2tabnext
+  call assert_equal(3, diff_filler(5))
+  call assert_equal(0, diff_filler(6))
+  call assert_equal(0, diff_filler(7))
+
+  " Manual diff update would refresh the diff since we previously changed mark
+  " a's location above.
+  diffupdate
+  call assert_equal(0, diff_filler(5))
+  call assert_equal(0, diff_filler(6))
+  call assert_equal(1, diff_filler(7))
+
+  " Go back to tab 1. Reset diff anchor to global value and make sure it uses
+  " mark a again.
+  1tabnext
+  set diffanchors<
+  call assert_equal(2, diff_filler(1))
+  call assert_equal(0, diff_filler(2))
+
+  " Now, change the global diff anchor to mark b. This should affect all tabs
+  " including tab 2 which should update automatically.
+  set diffanchors='b
+  call assert_equal(0, diff_filler(1))
+  call assert_equal(2, diff_filler(2))
+
+  2tabnext
+  call assert_equal(0, diff_filler(5))
+  call assert_equal(3, diff_filler(6))
+  call assert_equal(0, diff_filler(7))
+
+  %bw!
+  set diffopt&
+  set diffanchors&
+endfunc
+
+" Test that using diff anchors with window/buffer-local addresses will work as
+" expected and use the relevant window/buffer instead of curbuf/curwin.
+func Test_diffanchors_buf_win_local_addresses()
+  " Win 1-3 point to buffer 1. Set up different window-specific jump history
+  " Win 2 is the one we activate diff mode on.
+  call setline(1, range(1, 15))
+  norm 2gg
+  norm 3gg
+
+  split
+  norm 4gg
+  norm 5gg
+
+  split
+  norm 11gg
+  norm 12gg
+  call setline(10, 'new text 1') " update the '. mark to line 10
+
+  " Win 4 points to buffer 2
+  botright vert new
+  call setline(1, range(101, 110))
+  norm 8gg
+  norm 9gg
+  call setline(3, 'new text 2') " update the '. mark to line 3
+
+  2wincmd w
+  diffthis
+  4wincmd w
+  diffthis
+
+  " Test buffer-local marks using '. Should be anchored to lines 10 / 3.
+  set diffopt=internal,filler,anchor
+  set diffanchors='.
+  4wincmd w
+  call assert_equal(7, diff_filler(3))
+
+  " Test window-local marks using '' Should be anchored to lines 4 / 8.
+  " Note that windows 1 & 3 point to the buffer being diff'ed but are not used
+  " for diffing themselves and therefore should not be used. Windows 2 & 4
+  " should be used.
+  set diffanchors=''
+  2wincmd w
+  call assert_equal(4, diff_filler(4))
+
+  " Also test "." for the current cursor position, which is also
+  " window-specific. Make sure the cursor position at the longer file doesn't
+  " result in the other file using out of bounds line number.
+  4wincmd w
+  norm G
+  2wincmd w
+  norm G
+  set diffanchors=.
+  diffupdate
+  4wincmd w
+  call assert_equal(5, diff_filler(10))
+
+  %bw!
+  set diffopt&
+  set diffanchors&
+endfunc
+
+" Test diff anchors error handling for anchors that fail to resolve to a line.
+" These are not handled during option parsing because they depend on the
+" specifics of the buffer at diff time.
+func Test_diffanchors_invalid()
+  call setline(1, range(1, 5))
+  new
+  call setline(1, range(11, 20))
+  set diffopt=internal,filler,anchor
+  windo diffthis
+  1wincmd w
+
+  " Line numbers that are out of bounds should be an error
+  set diffanchors=0
+  call assert_fails('diffupdate', 'E16:')
+  set diffanchors=1
+  diffupdate
+  set diffanchors=$
+  diffupdate
+  set diffanchors=$+1
+  diffupdate
+  set diffanchors=$+2
+  call assert_fails('diffupdate', 'E16:')
+
+  " Test that non-existent marks in any one buffer will be detected
+  set diffanchors='a
+  call assert_fails('diffupdate', 'E20:')
+  2mark a
+  call assert_fails('diffupdate', 'E20:')
+
+  set diffanchors=1
+  setlocal diffanchors='a
+  diffupdate
+
+  set diffanchors<
+  windo 2mark a
+  set diffanchors='b
+  call assert_fails('diffupdate', 'E20:')
+  set diffanchors='a
+  diffupdate
+
+  " File marks are ok to use for anchors only if it is in the same file
+  1wincmd w
+  3mark C
+  setlocal diffanchors='C
+  diffupdate
+  set diffanchors='C
+  call assert_fails('diffupdate', 'E20:')
+
+  " Buffer-local marks also can only be used in buffers that have them.
+  set diffanchors=1
+  exec "norm 1ggVj\<Esc>"
+  setlocal diffanchors='<
+  diffupdate
+  set diffanchors='<
+  call assert_fails('diffupdate', 'E20:')
+
+  " Pattern search that failed will be an error too
+  let @/='orig_search_pat'
+  set diffanchors=1/5/
+  diffupdate
+  call assert_equal('orig_search_pat', @/) " also check we don't pollute the search register
+  set diffanchors=1/does_not_exist/
+  call assert_fails('diffupdate', 'E1550:')
+  call assert_equal('orig_search_pat', @/)
+
+  " Hidden buffers are not supported right now
+  hide
+  call assert_fails('diffupdate', 'E1562:')
+
+  %bw!
+  set diffopt&
+  set diffanchors&
+endfunc
+
+" Test diffget/diffput behaviors when using diff anchors which could create
+" adjacent diff blocks.
+func Test_diffget_diffput_diffanchors()
+  set diffanchors=1/anchor/
+  set diffopt=internal,filler,anchor
+
+  call setline(1, ['1', 'anchor1', '4'])
+  diffthis
+  new
+  call setline(1, ['2', '3', 'anchor2', '4', '5'])
+  diffthis
+  wincmd w
+
+  " Test using no-range diffget. It should grab the closest diff block only,
+  " even if there are multiple adjacent blocks.
+  2
+  diffget
+  call assert_equal(['1', 'anchor2', '4'], getline(1, '$'))
+  diffget
+  call assert_equal(['2', '3', 'anchor2', '4'], getline(1, '$'))
+
+  " Test using a range to get/put all the adjacent diff blocks.
+  1,$delete
+  call setline(1, ['anchor1', '4'])
+  0,1 diffget
+  call assert_equal(['2', '3', 'anchor2', '4'], getline(1, '$'))
+
+  1,$delete
+  call setline(1, ['anchor1', '4'])
+  0,$+1 diffget
+  call assert_equal(['2', '3', 'anchor2', '4', '5'], getline(1, '$'))
+
+  1,$delete
+  call setline(1, ['anchor1', '4'])
+  0,1 diffput
+  wincmd w
+  call assert_equal(['anchor1', '4', '5'], getline(1,'$'))
+
+  %bw!
+  set diffopt&
+  set diffanchors&
+endfunc
+
+func Test_diff_add_prop_in_autocmd()
+  CheckScreendump
+
+  let lines =<< trim END
+    func MyDiff() abort
+      let f1 = readfile(v:fname_in)
+      let f2 = readfile(v:fname_new)
+      let f0 = diff(f1, f2)
+      call writefile(split(f0, "\n"), v:fname_out)
+    endfunc
+
+    call prop_type_add('myprop', #{highlight: 'Search', override: 1})
+    autocmd OptionSet diff call prop_add(1, 1, #{type: 'myprop', length: 100})
+    set diffexpr=MyDiff()
+  END
+  call writefile(lines, 'Xtest_diff_add_prop_in_autocmd', 'D')
+  call writefile(['foo', 'bar', 'baz'], 'Xdiffsplit_file', 'D')
+
+  let buf = RunMNVInTerminal('-S Xtest_diff_add_prop_in_autocmd', {})
+  call term_sendkeys(buf, ":diffsplit Xdiffsplit_file\<CR>")
+  call VerifyScreenDump(buf, 'Test_diff_add_prop_in_autocmd_01', {})
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+" this was causing a use-after-free by calling winframe_remove() recursively
+func Test_diffexpr_wipe_buffers()
+  CheckRunMNVInTerminal
+
+  let lines =<< trim END
+    def DiffFuncExpr()
+      var in: list<string> = readfile(v:fname_in)
+      var new = readfile(v:fname_new)
+      var out: string = diff(in, new)
+      writefile(split(out, "n"), v:fname_out)
+    enddef
+
+    new
+    vnew
+    set diffexpr=DiffFuncExpr()
+    wincmd l
+    new
+    cal setline(1,range(20))
+    wind difft
+    wincm w
+    hid
+    %bw!
+  END
+  call writefile(lines, 'Xtest_diffexpr_wipe', 'D')
+
+  let buf = RunMNVInTerminal('Xtest_diffexpr_wipe', {})
+  call term_sendkeys(buf, ":so\<CR>")
+  call WaitForAssert({-> assert_match('4 buffers wiped out', term_getline(buf, 20))})
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+func Test_diffput_to_empty_buf()
+  CheckScreendump
+
+  let lines =<< trim END
+    call setline(1, ['foo', 'bar', 'baz'])
+    rightbelow vnew
+    windo diffthis
+    windo set cursorline nofoldenable
+    wincmd t
+  END
+  call writefile(lines, 'Xtest_diffput_to_empty_buf', 'D')
+
+  let buf = RunMNVInTerminal('-S Xtest_diffput_to_empty_buf', {})
+  call VerifyScreenDump(buf, 'Test_diffput_to_empty_buf_01', {})
+  call term_sendkeys(buf, '0')  " Trigger an initial 'cursorbind' check.
+  call VerifyScreenDump(buf, 'Test_diffput_to_empty_buf_01', {})
+  call term_sendkeys(buf, ":diffput | echo\<CR>")
+  call VerifyScreenDump(buf, 'Test_diffput_to_empty_buf_02', {})
+  call term_sendkeys(buf, ":redraw!\<CR>")
+  call VerifyScreenDump(buf, 'Test_diffput_to_empty_buf_02', {})
+  call term_sendkeys(buf, 'j')
+  call VerifyScreenDump(buf, 'Test_diffput_to_empty_buf_03', {})
+
+  call StopMNVInTerminal(buf)
+endfunc
+
+" mnv: shiftwidth=2 sts=2 expandtab