testing: Clarify why incomplete tests cause g_test_failed()


Signed-off-by: Simon McVittie <smcv@collabora.com>
diff --git a/glib/tests/testing.c b/glib/tests/testing.c
index de95f26..0c2cf5d 100644
--- a/glib/tests/testing.c
+++ b/glib/tests/testing.c
@@ -648,7 +648,10 @@
   if (g_test_subprocess ())
     {
       g_test_incomplete ("not done");
-      g_assert (g_test_failed ());
+      /* This function really means "the test concluded with a non-successful
+       * status" rather than "the test failed": it is documented to return
+       * true for skipped and incomplete tests, not just for failures. */
+      g_assert_true (g_test_failed ());
       return;
     }
   g_test_trap_subprocess (NULL, 0, 0);