[gtksourceview] testsuite: give language id on test failure

[Christian Hergert <chergert src gnome org>]

commit 1ac454bf8886087bd6aa546e031de425331140e7
Author: Christian Hergert <chergert redhat com>
Date:   Fri Jun 24 11:59:03 2022 -0700

    testsuite: give language id on test failure
    
    If we discover a language and expected NULL, it is handy to see what
    language failed from the CI runner so that we can easily point to it
    from merge requests.

 testsuite/test-languagemanager.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/testsuite/test-languagemanager.c b/testsuite/test-languagemanager.c
index 85c4d178..1d335eea 100644
--- a/testsuite/test-languagemanager.c
+++ b/testsuite/test-languagemanager.c
@@ -123,6 +123,14 @@ test_guess_language_empty_empty (void)
        gtk_source_language_manager_guess_language (lm, "", "");
 }
 
+static inline void
+assert_null_language (GtkSourceLanguage *l)
+{
+  if (l != NULL)
+    g_error ("Expected NULL language, got %s",
+             gtk_source_language_get_id (l));
+}
+
 static void
 test_guess_language (void)
 {
@@ -144,16 +152,16 @@ test_guess_language (void)
        g_test_trap_assert_failed ();
 
        l = gtk_source_language_manager_guess_language (lm, "foo.abcdef", NULL);
-       g_assert_null (l);
+       assert_null_language (l);
 
        l = gtk_source_language_manager_guess_language (lm, "foo.abcdef", "");
-       g_assert_null (l);
+       assert_null_language (l);
 
        l = gtk_source_language_manager_guess_language (lm, NULL, "image/png");
-       g_assert_null (l);
+       assert_null_language (l);
 
        l = gtk_source_language_manager_guess_language (lm, "", "image/png");
-       g_assert_null (l);
+       assert_null_language (l);
 
        l = gtk_source_language_manager_guess_language (lm, "foo.c", NULL);
        g_assert_cmpstr (gtk_source_language_get_id (l), ==, "c");