improve unit tests

lib/utils/mu-regex.cc

@@ -33,8 +33,15 @@ test_regex_match()
 	auto rx = Regex::make("a.*b.c");
 	assert_valid_result(rx);
 
+	assert_equal(mu_format("{}", *rx), "/a.*b.c/");
+
 	g_assert_true(rx->matches("axxxxxbqc"));
 	g_assert_false(rx->matches("axxxxxbqqc"));
+
+	{ // unset matches nothing.
+		Regex rx2;
+		g_assert_false(rx2.matches(""));
+	}
 }
 
 
@@ -43,7 +50,6 @@ test_regex_match2()
 {
 	Regex rx;
 	{
-
 		std::string foo = "h.llo";
 		rx = unwrap(Regex::make(foo.c_str()));
 	}
@@ -61,16 +67,37 @@ test_regex_replace()
 	{
 		auto rx = Regex::make("f.o");
 		assert_valid_result(rx);
-		assert_equal(rx->replace("foobar", "cuux"), "cuuxbar");
+		assert_equal(rx->replace("foobar", "cuux").value_or("error"), "cuuxbar");
 	}
 
 	{
 		auto rx = Regex::make("f.o", G_REGEX_MULTILINE);
 		assert_valid_result(rx);
-		assert_equal(rx->replace("foobar\nfoobar", "cuux"), "cuuxbar\ncuuxbar");
+		assert_equal(rx->replace("foobar\nfoobar", "cuux").value_or("error"),
+			     "cuuxbar\ncuuxbar");
 	}
 }
 
+
+static void
+test_regex_fail()
+{
+	allow_warnings();
+
+	{ // unset rx can't replace / error.
+		Regex rx;
+		assert_equal(mu_format("{}", rx), "//");
+		g_assert_false(!!rx.replace("foo", "bar"));
+	}
+
+	{
+		auto rx = Regex::make("(");
+		g_assert_false(!!rx);
+
+	}
+
+}
+
 int
 main(int argc, char* argv[])
 {
@@ -79,6 +106,7 @@ main(int argc, char* argv[])
 	g_test_add_func("/regex/match", test_regex_match);
 	g_test_add_func("/regex/match2", test_regex_match2);
 	g_test_add_func("/regex/replace", test_regex_replace);
+	g_test_add_func("/regex/fail", test_regex_fail);
 
 	return g_test_run();
 }