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

anntzer · anntzer · commit 876beccb8fa2 · 2018-12-11T00:25:04.000+01:00
Otherwise the error message can be quite obscure.
diff --git a/lib/matplotlib/tests/__init__.py b/lib/matplotlib/tests/__init__.py
@@ -1,9 +1,8 @@
-import os
+from pathlib import Path
 
 
-# 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. '
diff --git a/pytest.ini b/pytest.ini
@@ -1,4 +1,6 @@
 [pytest]
+minversion = 3.6
+
 testpaths = lib
 python_files = test_*.py
 
