Restore accidentally removed pytest.ini and tests.py.

pytest.ini

@@ -1,7 +1,12 @@
-[pytest]
-# NOTE: Because tests can be run from an installed copy, most of our Pytest
+# Because tests can be run from an installed copy, most of our Pytest
 # configuration is in the `pytest_configure` function in
 # `lib/matplotlib/testing/conftest.py`. This configuration file exists only to
-# prevent Pytest from wasting time trying to check examples and documentation
-# files that are not really tests.
+# set a minimum pytest version and to prevent pytest from wasting time trying
+# to check examples and documentation files that are not really tests.
+
+[pytest]
+minversion = 3.6
+
 testpaths = lib
+python_files = test_*.py
+junit_family = xunit2

tests.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+#
+# This allows running the matplotlib tests from the command line: e.g.
+#
+#   $ python tests.py -v -d
+#
+# The arguments are identical to the arguments accepted by pytest.
+#
+# See http://doc.pytest.org/ for a detailed description of these options.
+
+import sys
+import argparse
+
+
+if __name__ == '__main__':
+    try:
+        from matplotlib import test
+    except ImportError:
+        print('matplotlib.test could not be imported.\n\n'
+              'Try a virtual env and `pip install -e .`')
+        sys.exit(-1)
+
+    parser = argparse.ArgumentParser(add_help=False)
+    parser.add_argument('--recursionlimit', type=int, default=None,
+                        help='Specify recursionlimit for test run')
+    args, extra_args = parser.parse_known_args()
+
+    print('Python byte-compilation optimization level:', sys.flags.optimize)
+
+    if args.recursionlimit is not None:  # Will trigger deprecation.
+        retcode = test(argv=extra_args, recursionlimit=args.recursionlimit)
+    else:
+        retcode = test(argv=extra_args)
+    sys.exit(retcode)