1 files changed, 542 insertions, 0 deletions
diff --git a/json4cpp/tests/src/unit-capacity.cpp b/json4cpp/tests/src/unit-capacity.cpp
new file mode 100644
index 0000000000..98fcd00892
--- /dev/null
+++ b/json4cpp/tests/src/unit-capacity.cpp
@@ -0,0 +1,542 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+TEST_CASE("capacity")
+{
+    SECTION("empty()")
+    {
+        SECTION("boolean")
+        {
+            json j = true; // NOLINT(misc-const-correctness)
+            const json j_const = true;
+
+            SECTION("result of empty")
+            {
+                CHECK(j.empty() == false);
+                CHECK(j_const.empty() == false);
+            }
+
+            SECTION("definition of empty")
+            {
+                CHECK(j.empty() == (j.begin() == j.end()));
+                CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+            }
+        }
+
+        SECTION("string")
+        {
+            json j = "hello world"; // NOLINT(misc-const-correctness)
+            const json j_const = "hello world";
+
+            SECTION("result of empty")
+            {
+                CHECK(j.empty() == false);
+                CHECK(j_const.empty() == false);
+            }
+
+            SECTION("definition of empty")
+            {
+                CHECK(j.empty() == (j.begin() == j.end()));
+                CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+            }
+        }
+
+        SECTION("array")
+        {
+            SECTION("empty array")
+            {
+                json j = json::array(); // NOLINT(misc-const-correctness)
+                const json j_const = json::array();
+
+                SECTION("result of empty")
+                {
+                    CHECK(j.empty() == true);
+                    CHECK(j_const.empty() == true);
+                }
+
+                SECTION("definition of empty")
+                {
+                    CHECK(j.empty() == (j.begin() == j.end()));
+                    CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+                }
+            }
+
+            SECTION("filled array")
+            {
+                json j = {1, 2, 3}; // NOLINT(misc-const-correctness)
+                const json j_const = {1, 2, 3};
+
+                SECTION("result of empty")
+                {
+                    CHECK(j.empty() == false);
+                    CHECK(j_const.empty() == false);
+                }
+
+                SECTION("definition of empty")
+                {
+                    CHECK(j.empty() == (j.begin() == j.end()));
+                    CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+                }
+            }
+        }
+
+        SECTION("object")
+        {
+            SECTION("empty object")
+            {
+                json j = json::object(); // NOLINT(misc-const-correctness)
+                const json j_const = json::object();
+
+                SECTION("result of empty")
+                {
+                    CHECK(j.empty() == true);
+                    CHECK(j_const.empty() == true);
+                }
+
+                SECTION("definition of empty")
+                {
+                    CHECK(j.empty() == (j.begin() == j.end()));
+                    CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+                }
+            }
+
+            SECTION("filled object")
+            {
+                json j = {{"one", 1}, {"two", 2}, {"three", 3}}; // NOLINT(misc-const-correctness)
+                const json j_const = {{"one", 1}, {"two", 2}, {"three", 3}};
+
+                SECTION("result of empty")
+                {
+                    CHECK(j.empty() == false);
+                    CHECK(j_const.empty() == false);
+                }
+
+                SECTION("definition of empty")
+                {
+                    CHECK(j.empty() == (j.begin() == j.end()));
+                    CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+                }
+            }
+        }
+
+        SECTION("number (integer)")
+        {
+            json j = -23; // NOLINT(misc-const-correctness)
+            const json j_const = -23;
+
+            SECTION("result of empty")
+            {
+                CHECK(j.empty() == false);
+                CHECK(j_const.empty() == false);
+            }
+
+            SECTION("definition of empty")
+            {
+                CHECK(j.empty() == (j.begin() == j.end()));
+                CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+            }
+        }
+
+        SECTION("number (unsigned)")
+        {
+            json j = 23u; // NOLINT(misc-const-correctness)
+            const json j_const = 23u;
+
+            SECTION("result of empty")
+            {
+                CHECK(j.empty() == false);
+                CHECK(j_const.empty() == false);
+            }
+
+            SECTION("definition of empty")
+            {
+                CHECK(j.empty() == (j.begin() == j.end()));
+                CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+            }
+        }
+
+        SECTION("number (float)")
+        {
+            json j = 23.42; // NOLINT(misc-const-correctness)
+            const json j_const = 23.42;
+
+            SECTION("result of empty")
+            {
+                CHECK(j.empty() == false);
+                CHECK(j_const.empty() == false);
+            }
+
+            SECTION("definition of empty")
+            {
+                CHECK(j.empty() == (j.begin() == j.end()));
+                CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+            }
+        }
+
+        SECTION("null")
+        {
+            json j = nullptr; // NOLINT(misc-const-correctness)
+            const json j_const = nullptr;
+
+            SECTION("result of empty")
+            {
+                CHECK(j.empty() == true);
+                CHECK(j_const.empty() == true);
+            }
+
+            SECTION("definition of empty")
+            {
+                CHECK(j.empty() == (j.begin() == j.end()));
+                CHECK(j_const.empty() == (j_const.begin() == j_const.end()));
+            }
+        }
+    }
+
+    SECTION("size()")
+    {
+        SECTION("boolean")
+        {
+            json j = true; // NOLINT(misc-const-correctness)
+            const json j_const = true;
+
+            SECTION("result of size")
+            {
+                CHECK(j.size() == 1);
+                CHECK(j_const.size() == 1);
+            }
+
+            SECTION("definition of size")
+            {
+                CHECK(std::distance(j.begin(), j.end()) == j.size());
+                CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+            }
+        }
+
+        SECTION("string")
+        {
+            json j = "hello world"; // NOLINT(misc-const-correctness)
+            const json j_const = "hello world";
+
+            SECTION("result of size")
+            {
+                CHECK(j.size() == 1);
+                CHECK(j_const.size() == 1);
+            }
+
+            SECTION("definition of size")
+            {
+                CHECK(std::distance(j.begin(), j.end()) == j.size());
+                CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+            }
+        }
+
+        SECTION("array")
+        {
+            SECTION("empty array")
+            {
+                json j = json::array(); // NOLINT(misc-const-correctness)
+                const json j_const = json::array();
+
+                SECTION("result of size")
+                {
+                    CHECK(j.size() == 0);
+                    CHECK(j_const.size() == 0);
+                }
+
+                SECTION("definition of size")
+                {
+                    CHECK(std::distance(j.begin(), j.end()) == j.size());
+                    CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                    CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                    CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+                }
+            }
+
+            SECTION("filled array")
+            {
+                json j = {1, 2, 3}; // NOLINT(misc-const-correctness)
+                const json j_const = {1, 2, 3};
+
+                SECTION("result of size")
+                {
+                    CHECK(j.size() == 3);
+                    CHECK(j_const.size() == 3);
+                }
+
+                SECTION("definition of size")
+                {
+                    CHECK(std::distance(j.begin(), j.end()) == j.size());
+                    CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                    CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                    CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+                }
+            }
+        }
+
+        SECTION("object")
+        {
+            SECTION("empty object")
+            {
+                json j = json::object(); // NOLINT(misc-const-correctness)
+                const json j_const = json::object();
+
+                SECTION("result of size")
+                {
+                    CHECK(j.size() == 0);
+                    CHECK(j_const.size() == 0);
+                }
+
+                SECTION("definition of size")
+                {
+                    CHECK(std::distance(j.begin(), j.end()) == j.size());
+                    CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                    CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                    CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+                }
+            }
+
+            SECTION("filled object")
+            {
+                json j = {{"one", 1}, {"two", 2}, {"three", 3}}; // NOLINT(misc-const-correctness)
+                const json j_const = {{"one", 1}, {"two", 2}, {"three", 3}};
+
+                SECTION("result of size")
+                {
+                    CHECK(j.size() == 3);
+                    CHECK(j_const.size() == 3);
+                }
+
+                SECTION("definition of size")
+                {
+                    CHECK(std::distance(j.begin(), j.end()) == j.size());
+                    CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                    CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                    CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+                }
+            }
+        }
+
+        SECTION("number (integer)")
+        {
+            json j = -23; // NOLINT(misc-const-correctness)
+            const json j_const = -23;
+
+            SECTION("result of size")
+            {
+                CHECK(j.size() == 1);
+                CHECK(j_const.size() == 1);
+            }
+
+            SECTION("definition of size")
+            {
+                CHECK(std::distance(j.begin(), j.end()) == j.size());
+                CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+            }
+        }
+
+        SECTION("number (unsigned)")
+        {
+            json j = 23u; // NOLINT(misc-const-correctness)
+            const json j_const = 23u;
+
+            SECTION("result of size")
+            {
+                CHECK(j.size() == 1);
+                CHECK(j_const.size() == 1);
+            }
+
+            SECTION("definition of size")
+            {
+                CHECK(std::distance(j.begin(), j.end()) == j.size());
+                CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+            }
+        }
+
+        SECTION("number (float)")
+        {
+            json j = 23.42; // NOLINT(misc-const-correctness)
+            const json j_const = 23.42;
+
+            SECTION("result of size")
+            {
+                CHECK(j.size() == 1);
+                CHECK(j_const.size() == 1);
+            }
+
+            SECTION("definition of size")
+            {
+                CHECK(std::distance(j.begin(), j.end()) == j.size());
+                CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+            }
+        }
+
+        SECTION("null")
+        {
+            json j = nullptr; // NOLINT(misc-const-correctness)
+            const json j_const = nullptr;
+
+            SECTION("result of size")
+            {
+                CHECK(j.size() == 0);
+                CHECK(j_const.size() == 0);
+            }
+
+            SECTION("definition of size")
+            {
+                CHECK(std::distance(j.begin(), j.end()) == j.size());
+                CHECK(std::distance(j_const.begin(), j_const.end()) == j_const.size());
+                CHECK(std::distance(j.rbegin(), j.rend()) == j.size());
+                CHECK(std::distance(j_const.crbegin(), j_const.crend()) == j_const.size());
+            }
+        }
+    }
+
+    SECTION("max_size()")
+    {
+        SECTION("boolean")
+        {
+            json j = true; // NOLINT(misc-const-correctness)
+            const json j_const = true;
+
+            SECTION("result of max_size")
+            {
+                CHECK(j.max_size() == 1);
+                CHECK(j_const.max_size() == 1);
+            }
+        }
+
+        SECTION("string")
+        {
+            json j = "hello world"; // NOLINT(misc-const-correctness)
+            const json j_const = "hello world";
+
+            SECTION("result of max_size")
+            {
+                CHECK(j.max_size() == 1);
+                CHECK(j_const.max_size() == 1);
+            }
+        }
+
+        SECTION("array")
+        {
+            SECTION("empty array")
+            {
+                json j = json::array(); // NOLINT(misc-const-correctness)
+                const json j_const = json::array();
+
+                SECTION("result of max_size")
+                {
+                    CHECK(j.max_size() >= j.size());
+                    CHECK(j_const.max_size() >= j_const.size());
+                }
+            }
+
+            SECTION("filled array")
+            {
+                json j = {1, 2, 3}; // NOLINT(misc-const-correctness)
+                const json j_const = {1, 2, 3};
+
+                SECTION("result of max_size")
+                {
+                    CHECK(j.max_size() >= j.size());
+                    CHECK(j_const.max_size() >= j_const.size());
+                }
+            }
+        }
+
+        SECTION("object")
+        {
+            SECTION("empty object")
+            {
+                json j = json::object(); // NOLINT(misc-const-correctness)
+                const json j_const = json::object();
+
+                SECTION("result of max_size")
+                {
+                    CHECK(j.max_size() >= j.size());
+                    CHECK(j_const.max_size() >= j_const.size());
+                }
+            }
+
+            SECTION("filled object")
+            {
+                json j = {{"one", 1}, {"two", 2}, {"three", 3}}; // NOLINT(misc-const-correctness)
+                const json j_const = {{"one", 1}, {"two", 2}, {"three", 3}};
+
+                SECTION("result of max_size")
+                {
+                    CHECK(j.max_size() >= j.size());
+                    CHECK(j_const.max_size() >= j_const.size());
+                }
+            }
+        }
+
+        SECTION("number (integer)")
+        {
+            json j = -23; // NOLINT(misc-const-correctness)
+            const json j_const = -23;
+
+            SECTION("result of max_size")
+            {
+                CHECK(j.max_size() == 1);
+                CHECK(j_const.max_size() == 1);
+            }
+        }
+
+        SECTION("number (unsigned)")
+        {
+            json j = 23u; // NOLINT(misc-const-correctness)
+            const json j_const = 23u;
+
+            SECTION("result of max_size")
+            {
+                CHECK(j.max_size() == 1);
+                CHECK(j_const.max_size() == 1);
+            }
+        }
+
+        SECTION("number (float)")
+        {
+            json j = 23.42; // NOLINT(misc-const-correctness)
+            const json j_const = 23.42;
+
+            SECTION("result of max_size")
+            {
+                CHECK(j.max_size() == 1);
+                CHECK(j_const.max_size() == 1);
+            }
+        }
+
+        SECTION("null")
+        {
+            json j = nullptr; // NOLINT(misc-const-correctness)
+            const json j_const = nullptr;
+
+            SECTION("result of max_size")
+            {
+                CHECK(j.max_size() == 0);
+                CHECK(j_const.max_size() == 0);
+            }
+        }
+    }
+}