Backport PR #12726: Fix test_non_gui_warning for Azure (and mplcairo). (#12731)

meeseeksmachine · timhoffm · commit 2aede99b02eb · 2018-11-04T08:58:38.000+01:00
diff --git a/lib/matplotlib/tests/test_backend_bases.py b/lib/matplotlib/tests/test_backend_bases.py
@@ -56,11 +56,11 @@ def test_get_default_filename(tmpdir):
 
 
 @pytest.mark.backend('pdf')
-@pytest.mark.skipif('SYSTEM_TEAMFOUNDATIONCOLLECTIONURI' in os.environ,
-                    reason="this test fails an azure for unknown reasons")
-def test_non_gui_warning():
+def test_non_gui_warning(monkeypatch):
     plt.subplots()
 
+    monkeypatch.setitem(os.environ, "DISPLAY", ":999")
+
     with pytest.warns(UserWarning) as rec:
         plt.show()
         assert len(rec) == 1
