master 02bf6650b0: Fix failing image test on nox builds

[Basil L. Contovounesios]

branch: master
commit 02bf6650b073ffad702772a2ebae20023fa8276a
Author: Basil L. Contovounesios <contovob@tcd.ie>
Commit: Basil L. Contovounesios <contovob@tcd.ie>

    Fix failing image test on nox builds
    
    * test/lisp/image-tests.el (image-supported-file-p/built-in): Skip
    test in --without-x builds.
---
 test/lisp/image-tests.el | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test/lisp/image-tests.el b/test/lisp/image-tests.el
index 908df09f15..bc8c3636c3 100644
--- a/test/lisp/image-tests.el
+++ b/test/lisp/image-tests.el
@@ -75,7 +75,8 @@
   (should-not (find-image '((:type png :file "does-not-exist-foo-bar.png")))))
 
 (ert-deftest image-supported-file-p/built-in ()
-  ;; (skip-unless (image-type-available-p 'pbm)) ; always built-in
+  ;; (skip-unless (image-type-available-p 'pbm)) ; Always built-in
+  (skip-unless (display-images-p))               ; (except in nox builds).
   (should (eq (image-supported-file-p "foo.pbm") 'pbm)))
 
 (ert-deftest image-supported-file-p/optional ()