test: add test for from/into based conversions

tests/CMakeLists.txt

@@ -29,6 +29,7 @@ set(TEST_NAMES
     test_parse_unicode
     test_error_detection
     test_format_error
+    test_extended_conversions
 )
 
 CHECK_CXX_COMPILER_FLAG("-Wall" COMPILER_SUPPORTS_WALL)

tests/test_extended_conversions.cpp

@@ -0,0 +1,82 @@
+#define BOOST_TEST_MODULE "test_extended_conversions"
+#ifdef UNITTEST_FRAMEWORK_LIBRARY_EXIST
+#include <boost/test/unit_test.hpp>
+#else
+#define BOOST_TEST_NO_LIB
+#include <boost/test/included/unit_test.hpp>
+#endif
+#include <toml.hpp>
+
+namespace extlib
+{
+struct foo
+{
+    int a;
+    std::string b;
+};
+struct bar
+{
+    int a;
+    std::string b;
+
+    void from_toml(const toml::value& v)
+    {
+        this->a = toml::find<int>(v, "a");
+        this->b = toml::find<std::string>(v, "b");
+        return ;
+    }
+
+    toml::table into_toml() const
+    {
+        return toml::table{{"a", this->a}, {"b", this->b}};
+    }
+};
+} // extlib
+
+namespace toml
+{
+template<>
+struct from<extlib::foo>
+{
+    static extlib::foo from_toml(const toml::value& v)
+    {
+        return extlib::foo{toml::find<int>(v, "a"), toml::find<std::string>(v, "b")};
+    }
+};
+
+template<>
+struct into<extlib::foo>
+{
+    static toml::table into_toml(const extlib::foo& f)
+    {
+        return toml::table{{"a", f.a}, {"b", f.b}};
+    }
+};
+} // toml
+
+
+BOOST_AUTO_TEST_CASE(test_conversion_by_member_methods)
+{
+    const toml::value v{{"a", 42}, {"b", "baz"}};
+
+    const auto foo = toml::get<extlib::foo>(v);
+    BOOST_TEST(foo.a == 42);
+    BOOST_TEST(foo.b == "baz");
+
+    const toml::value v2(foo);
+
+    BOOST_TEST(v == v2);
+}
+
+BOOST_AUTO_TEST_CASE(test_conversion_by_specialization)
+{
+    const toml::value v{{"a", 42}, {"b", "baz"}};
+
+    const auto bar = toml::get<extlib::bar>(v);
+    BOOST_TEST(bar.a == 42);
+    BOOST_TEST(bar.b == "baz");
+
+    const toml::value v2(bar);
+
+    BOOST_TEST(v == v2);
+}