Fix memory management issues in Pgsql_Params leave sources of moves in a valid state.

tests/PgsqlTests/CMakeLists.txt

@@ -3,6 +3,7 @@ add_executable(PgsqlTests
     tst_Value.cpp
     tst_ArrayParser.cpp
     tst_Pgsql_oids.cpp
+    tst_Pgsql_Params.cpp
     )
 
 target_link_libraries(PgsqlTests PRIVATE

tests/PgsqlTests/tst_Pgsql_Params.cpp

@@ -0,0 +1,85 @@
+#include <gtest/gtest.h>
+#include <gmock/gmock-matchers.h>
+#include <string>
+#include <utility>
+#include <vector>
+#include "Pgsql_Params.h"
+#include "PrintTo_Qt.h"
+
+using namespace testing;
+using namespace Pgsql;
+
+namespace {
+	void expectValues(const Params &p, const std::vector<std::string> &expected)
+	{
+		ASSERT_EQ(p.size(), static_cast<int>(expected.size()));
+		for (int i = 0; i < p.size(); ++i) {
+			ASSERT_NE(p.values()[i], nullptr);
+			EXPECT_STREQ(p.values()[i], expected[i].c_str());
+		}
+	}
+}
+
+TEST(Pgsql_Params, CopyAssignIntoNonEmpty)
+{
+	Params src;
+	src.add("a");
+	src.add("bb");
+
+	Params dst;
+	dst.add("x");
+	dst.add("y");
+	dst.add("z");
+
+	dst = src;
+	expectValues(dst, {"a", "bb"});
+	expectValues(src, {"a", "bb"});
+}
+
+TEST(Pgsql_Params, CopyAssignIntoEmpty)
+{
+	Params src;
+	src.add("a");
+	src.add("bb");
+
+	Params dst;
+	dst = src;
+	expectValues(dst, {"a", "bb"});
+}
+
+TEST(Pgsql_Params, MoveAssignIntoNonEmpty)
+{
+	Params src;
+	src.add("a");
+	src.add("bb");
+
+	Params dst;
+	dst.add("x");
+	dst.add("y");
+	dst.add("z");
+
+	dst = std::move(src);
+	expectValues(dst, {"a", "bb"});
+}
+
+TEST(Pgsql_Params, CopyConstructorDoesNotAliasSource)
+{
+	Params src;
+	src.add("abc");
+
+	Params dst(src);
+	src.clear();
+	expectValues(dst, {"abc"});
+}
+
+TEST(Pgsql_Params, CopyPreservesNull)
+{
+	Params src;
+	src.add(std::optional<std::string>{});
+	src.add("v");
+
+	Params dst(src);
+	ASSERT_EQ(dst.size(), 2);
+	EXPECT_EQ(dst.values()[0], nullptr);
+	EXPECT_STREQ(dst.values()[1], "v");
+}