Fail-fast when trying to run tests with too-old pytest.

anntzer · anntzer · commit 833f48d4da59 · 2018-12-10T23:58:07.000+01:00
Otherwise the error message can be quite obscure.
diff --git a/lib/matplotlib/tests/__init__.py b/lib/matplotlib/tests/__init__.py
@@ -1,11 +1,15 @@
-import os
+from distutils.version import LooseVersion
+from pathlib import Path
 
+import pytest
 
-# Check that the test directories exist
-if not os.path.exists(os.path.join(
-        os.path.dirname(__file__), 'baseline_images')):
+
+# Check that the test directories exist.
+if not (Path(__file__).parent / 'baseline_images').exists():
     raise IOError(
         'The baseline image directory does not exist. '
         'This is most likely because the test data is not installed. '
         'You may need to install matplotlib from source to get the '
         'test data.')
+if LooseVersion(pytest.__version__) < "3.6":
+    raise RuntimeError('pytest>=3.6 is required to run the tests')
