[gjs: 5/12] tests: Add regression test for null returned GError

[Philip Chimento <pchimento src gnome org>]

commit 025636451169fbeaafc80d71e0c95b8222a11cfe
Author: Philip Chimento <philip chimento gmail com>
Date:   Sun Feb 14 13:43:12 2021 -0800

    tests: Add regression test for null returned GError
    
    In previous versions of GJS, returning (not throwing) a null GError from
    an introspected function would cause GJS to try to free it. Even though
    the bug has been fixed, add a regression test to make sure that it doesn't
    occur again in the future.
    
    See: #351

 installed-tests/js/testExceptions.js | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
---
diff --git a/installed-tests/js/testExceptions.js b/installed-tests/js/testExceptions.js
index 0262e43c..662b5297 100644
--- a/installed-tests/js/testExceptions.js
+++ b/installed-tests/js/testExceptions.js
@@ -205,3 +205,17 @@ describe('thrown GError', function () {
         expect(err.code).toEqual(Gio.IOErrorEnum.NOT_FOUND);
     });
 });
+
+describe('Returned GError', function () {
+    it('can be nullable', function () {
+        // expect a critical about passing in an invalid error domain, but this
+        // should not crash or log a critical about freeing a null GError
+        GLib.test_expect_message('GLib', GLib.LogLevelFlags.LEVEL_CRITICAL,
+            "g_error_new_literal: assertion 'domain != 0' failed");
+
+        expect(GLib.Error.new_literal(0, 0, 'message')).toBeNull();
+
+        GLib.test_assert_expected_messages_internal('GLib', 'testExceptions.js',
+            0, 'testGErrorMessages');
+    });
+});