Fix test_lazy_imports in presence of $MPLBACKEND or matplotlibrc.

anntzer · anntzer · commit 0fae3735f6da · 2019-05-07T17:49:42.000+02:00
$MPLBACKEND or the matplotlibrc can make matplotlib load a nondefault
backend (cough cough, mplcairo) by default which then makes the test
fail.  Overwrite these in the test.
diff --git a/lib/matplotlib/tests/test_basic.py b/lib/matplotlib/tests/test_basic.py
@@ -1,4 +1,5 @@
 import builtins
+import os
 import subprocess
 import sys
 import textwrap
@@ -50,8 +51,6 @@ def test_lazy_imports():
     assert 'urllib.request' not in sys.modules
     """)
 
-    subprocess.check_call([
-        sys.executable,
-        '-c',
-        source
-    ])
+    subprocess.check_call(
+        [sys.executable, '-c', source],
+        env={**os.environ, "MPLBACKEND": "", "MATPLOTLIBRC": os.devnull})
