Implemented FFI testing, mocked out bad cases and verified the correct operation of Rust modules

Author: Reim-developer

tests-ffi/time.cxx

@@ -0,0 +1,44 @@
+#include <cassert>
+#include <cstdint>
+#include <string>
+
+using std::string;
+using std::uint8_t;
+
+extern "C" enum class AllocResult : uint8_t {
+	OK,
+	NULL_DEFERENCE_ERR,
+	CONVERT_TO_STR_FAILED,
+};
+
+extern "C" AllocResult time_now(char **out);
+extern "C" void raw_free_c_str(char *str);
+
+void null_deference_test() {
+	using R = AllocResult;
+
+	auto result = time_now(nullptr);
+	assert(result != R::CONVERT_TO_STR_FAILED);
+	assert(result != R::OK);
+	assert(result == R::NULL_DEFERENCE_ERR);
+}
+
+void time_now_test() {
+	using R = AllocResult;
+
+	char *out = nullptr;
+	auto result = time_now(&out);
+	auto time_now_string = string(out);
+	raw_free_c_str(out);
+
+	assert(result != R::CONVERT_TO_STR_FAILED);
+	assert(result != R::NULL_DEFERENCE_ERR);
+	assert(result == R::OK);
+	assert(!time_now_string.empty());
+}
+
+int main() {
+	null_deference_test();
+	time_now_test();
+	return 0;
+}