feat: matches::str::eq for case-insensitively comparison

include/mimic++/Matcher.hpp

@@ -422,6 +422,17 @@ namespace mimicpp::matches
 	 */
 }
 
+namespace mimicpp
+{
+	/**
+	 * \brief Tag type, used in string matchers.
+	 * \ingroup EXPECTATION_MATCHERS_STRING
+	 */
+	struct case_insensitive_t
+	{
+	} constexpr case_insensitive{};
+}
+
 namespace mimicpp::matches::str
 {
 	/**
@@ -458,6 +469,30 @@ namespace mimicpp::matches::str
 		};
 	}
 
+	/**
+	 * \brief Tests, whether the target string compares case-insensitively equal to the expected string.
+	 * \tparam String The string type.
+	 * \param pattern The pattern object.
+	 */
+	template <typename String>
+	[[nodiscard]]
+	constexpr auto eq(String&& pattern, [[maybe_unused]] const case_insensitive_t)
+	{
+		using pattern_t = std::invoke_result_t<decltype(to_lower), String>;
+		return PredicateMatcher{
+			[]<lower_convertible T>(const pattern_t& target, T&& exp)
+				requires std::equality_comparable_with<pattern_t, std::invoke_result_t<decltype(to_lower), T>>
+			{
+				return target == mimicpp::to_lower(std::forward<T>(exp));
+			},
+			"is case-insensitively equal to {}",
+			"is case-insensitively not equal to {}",
+			std::tuple{
+				mimicpp::to_lower(std::forward<String>(pattern))
+			}
+		};
+	}
+
 	/**
 	 * \}
 	 */

test/unit-tests/StringMatchers.cpp

@@ -6,8 +6,12 @@
 #include "mimic++/Matcher.hpp"
 
 #include <catch2/catch_template_test_macros.hpp>
+#include <catch2/generators/catch_generators.hpp>
+#include <catch2/generators/catch_generators_range.hpp>
 #include <catch2/matchers/catch_matchers_string.hpp>
 
+#include <array>
+
 namespace matches = mimicpp::matches;
 
 TEST_CASE(
@@ -154,3 +158,68 @@ TEMPLATE_TEST_CASE(
 		std::u32string{U"Hello, World!"},
 		std::u32string{U"Hello, WOrld!"});
 }
+
+TEST_CASE(
+	"matches::str::eq supports case-insensitive comparison for char-strings.",
+	"[matcher][matcher::str]"
+)
+{
+	static constexpr std::array matches = std::to_array<const char*>(
+		{
+			"Hello, World!",
+			"hello, World!",
+			"Hello, world!",
+			"HelLo, world!"
+		});
+
+	static constexpr std::array mismatches = std::to_array<const char*>(
+		{
+			" hello, world!",
+			"hello, world! ",
+			"hello,world!"
+		});
+
+	const auto matcher = matches::str::eq(
+		"Hello, World!",
+		mimicpp::case_insensitive);
+	REQUIRE_THAT(
+		matcher.describe(),
+		Catch::Matchers::Equals("is case-insensitively equal to \"hello, world!\""));
+
+	SECTION("When target is equal, they match.")
+	{
+		const std::string target = GENERATE(from_range(matches));
+
+		REQUIRE(matcher.matches(target));
+	}
+
+	SECTION("When target is not equal, they do not match.")
+	{
+		const std::string target = GENERATE(from_range(mismatches));
+
+		REQUIRE(!matcher.matches(target));
+	}
+
+	SECTION("Matcher can be inverted.")
+	{
+		const auto invertedMatcher = !matches::str::eq("Hello, World!");
+
+		REQUIRE_THAT(
+			invertedMatcher.describe(),
+			Catch::Matchers::Equals("is case-insensitively not equal to \"hello, world!\""));
+
+		SECTION("When target is equal, they do not match.")
+		{
+			const std::string target = GENERATE(from_range(matches));
+
+			REQUIRE(!invertedMatcher.matches(target));
+		}
+
+		SECTION("When target is not equal, they do match.")
+		{
+			const std::string target = GENERATE(from_range(mismatches));
+
+			REQUIRE(invertedMatcher.matches(target));
+		}
+	}
+}