matplotlib · phobson · Jun 5, 2018 · May 23, 2018 · May 31, 2018
diff --git a/doc/api/next_api_changes/2018-02-15-AL-deprecations.rst b/doc/api/next_api_changes/2018-02-15-AL-deprecations.rst
@@ -25,7 +25,8 @@ The following classes, methods, functions, and attributes are deprecated:
 - ``mathtext.unichr_safe`` (use ``chr`` instead),
 - ``table.Table.get_child_artists`` (use ``get_children`` instead),
 - ``testing.compare.ImageComparisonTest``, ``testing.compare.compare_float``,
-- ``testing.decorators.skip_if_command_unavailable``.
+- ``testing.decorators.CleanupTest``,
+  ``testing.decorators.skip_if_command_unavailable``,
 - ``FigureCanvasQT.keyAutoRepeat`` (directly check
   ``event.guiEvent.isAutoRepeat()`` in the event handler to decide whether to
   handle autorepeated key presses).

diff --git a/doc/api/next_api_changes/2018-05-22-AL.rst b/doc/api/next_api_changes/2018-05-22-AL.rst
@@ -0,0 +1,4 @@
+The cleanup decorators and test classes in matplotlib.testing.decorators no longer destroy the warnings filter on exit
+``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````
+Instead, they restore the warnings filter that existed before the test started
+using ``warnings.catch_warnings``.
diff --git a/lib/matplotlib/testing/__init__.py b/lib/matplotlib/testing/__init__.py
@@ -3,6 +3,7 @@
 
 import matplotlib as mpl
 from matplotlib import cbook
+from matplotlib.cbook import MatplotlibDeprecationWarning
 
 
 def is_called_from_pytest():
@@ -38,10 +39,11 @@ def setup():
 
     mpl.use('Agg', warn=False)  # use Agg backend for these tests
 
-    # These settings *must* be hardcoded for running the comparison
-    # tests and are not necessarily the default values as specified in
-    # rcsetup.py
-    mpl.rcdefaults()  # Start with all defaults
+    # These settings *must* be hardcoded for running the comparison tests and
+    # are not necessarily the default values as specified in rcsetup.py
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", MatplotlibDeprecationWarning)
+        mpl.rcdefaults()  # Start with all defaults
 
     set_font_settings_for_testing()
     set_reproducibility_for_testing()
diff --git a/lib/matplotlib/testing/conftest.py b/lib/matplotlib/testing/conftest.py
@@ -1,7 +1,10 @@
+import warnings
+
 import pytest
 
 import matplotlib
 from matplotlib import cbook
+from matplotlib.cbook import MatplotlibDeprecationWarning
 
 
 def pytest_configure(config):
@@ -16,39 +19,39 @@ def pytest_unconfigure(config):
 
 @pytest.fixture(autouse=True)
 def mpl_test_settings(request):
-    from matplotlib.testing.decorators import _do_cleanup
-
-    original_units_registry = matplotlib.units.registry.copy()
-    original_settings = matplotlib.rcParams.copy()
-
-    backend = None
-    backend_marker = request.keywords.get('backend')
-    if backend_marker is not None:
-        assert len(backend_marker.args) == 1, \
-            "Marker 'backend' must specify 1 backend."
-        backend = backend_marker.args[0]
-        prev_backend = matplotlib.get_backend()
-
-    style = '_classic_test'  # Default of cleanup and image_comparison too.
-    style_marker = request.keywords.get('style')
-    if style_marker is not None:
-        assert len(style_marker.args) == 1, \
-            "Marker 'style' must specify 1 style."
-        style = style_marker.args[0]
-
-    matplotlib.testing.setup()
-    if backend is not None:
-        # This import must come after setup() so it doesn't load the default
-        # backend prematurely.
-        import matplotlib.pyplot as plt
-        plt.switch_backend(backend)
-    matplotlib.style.use(style)
-    try:
-        yield
-    finally:
+    from matplotlib.testing.decorators import _cleanup_cm
+
+    with _cleanup_cm():
+
+        backend = None
+        backend_marker = request.keywords.get('backend')
+        if backend_marker is not None:
+            assert len(backend_marker.args) == 1, \
+                "Marker 'backend' must specify 1 backend."
+            backend = backend_marker.args[0]
+            prev_backend = matplotlib.get_backend()
+
+        style = '_classic_test'  # Default of cleanup and image_comparison too.
+        style_marker = request.keywords.get('style')
+        if style_marker is not None:
+            assert len(style_marker.args) == 1, \
+                "Marker 'style' must specify 1 style."
+            style = style_marker.args[0]
+
+        matplotlib.testing.setup()
         if backend is not None:
-            plt.switch_backend(prev_backend)
-        _do_cleanup(original_units_registry, original_settings)
+            # This import must come after setup() so it doesn't load the
+            # default backend prematurely.
+            import matplotlib.pyplot as plt
+            plt.switch_backend(backend)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", MatplotlibDeprecationWarning)
+            matplotlib.style.use(style)
+        try:
+            yield
+        finally:
+            if backend is not None:
+                plt.switch_backend(prev_backend)
 
 
 @pytest.fixture

diff --git a/lib/matplotlib/testing/decorators.py b/lib/matplotlib/testing/decorators.py
@@ -1,3 +1,4 @@
+import contextlib
 from distutils.version import StrictVersion
 import functools
 import inspect
@@ -8,63 +9,49 @@
 import unittest
 import warnings
 
-# Note - don't import nose up here - import it only as needed in functions.
-# This allows other functions here to be used by pytest-based testing suites
-# without requiring nose to be installed.
-
-
 import matplotlib as mpl
 import matplotlib.style
 import matplotlib.units
 import matplotlib.testing
 from matplotlib import cbook
-from matplotlib import ticker
-from matplotlib import pyplot as plt
 from matplotlib import ft2font
-from matplotlib.testing.compare import (
-    comparable_formats, compare_images, make_test_filename)
+from matplotlib import pyplot as plt
+from matplotlib import ticker
 from . import is_called_from_pytest
+from .compare import comparable_formats, compare_images, make_test_filename
 from .exceptions import ImageComparisonFailure
 
 
-def _do_cleanup(original_units_registry, original_settings):
-    plt.close('all')
-
-    mpl.rcParams.clear()
-    mpl.rcParams.update(original_settings)
-    matplotlib.units.registry.clear()
-    matplotlib.units.registry.update(original_units_registry)
-    warnings.resetwarnings()  # reset any warning filters set in tests
-
-
-class CleanupTest(object):
-    @classmethod
-    def setup_class(cls):
-        cls.original_units_registry = matplotlib.units.registry.copy()
-        cls.original_settings = mpl.rcParams.copy()
-        matplotlib.testing.setup()
-
-    @classmethod
-    def teardown_class(cls):
-        _do_cleanup(cls.original_units_registry,
-                    cls.original_settings)
-
-    def test(self):
-        self._func()
+@contextlib.contextmanager
+def _cleanup_cm():
+    orig_units_registry = matplotlib.units.registry.copy()
+    try:
+        with warnings.catch_warnings(), matplotlib.rc_context():
+            yield
+    finally:
+        matplotlib.units.registry.clear()
+        matplotlib.units.registry.update(orig_units_registry)
+        plt.close("all")
 
 
 class CleanupTestCase(unittest.TestCase):
-    '''A wrapper for unittest.TestCase that includes cleanup operations'''
+    """A wrapper for unittest.TestCase that includes cleanup operations."""
     @classmethod
     def setUpClass(cls):
-        import matplotlib.units
-        cls.original_units_registry = matplotlib.units.registry.copy()
-        cls.original_settings = mpl.rcParams.copy()
+        cls._cm = _cleanup_cm().__enter__()
 
     @classmethod
     def tearDownClass(cls):
-        _do_cleanup(cls.original_units_registry,
-                    cls.original_settings)
+        cls._cm.__exit__(None, None, None)
+
+
+@cbook.deprecated("3.0")
+class CleanupTest(object):
+    setup_class = classmethod(CleanupTestCase.setUpClass.__func__)
+    teardown_class = classmethod(CleanupTestCase.tearDownClass.__func__)
+
+    def test(self):
+        self._func()
 
 
 def cleanup(style=None):
@@ -78,34 +65,23 @@ def cleanup(style=None):
         The name of the style to apply.
     """
 
-    # If cleanup is used without arguments, `style` will be a
-    # callable, and we pass it directly to the wrapper generator.  If
-    # cleanup if called with an argument, it is a string naming a
-    # style, and the function will be passed as an argument to what we
-    # return.  This is a confusing, but somewhat standard, pattern for
-    # writing a decorator with optional arguments.
+    # If cleanup is used without arguments, `style` will be a callable, and we
+    # pass it directly to the wrapper generator.  If cleanup if called with an
+    # argument, it is a string naming a style, and the function will be passed
+    # as an argument to what we return.  This is a confusing, but somewhat
+    # standard, pattern for writing a decorator with optional arguments.
 
     def make_cleanup(func):
         if inspect.isgeneratorfunction(func):
             @functools.wraps(func)
             def wrapped_callable(*args, **kwargs):
-                original_units_registry = matplotlib.units.registry.copy()
-                original_settings = mpl.rcParams.copy()
-                matplotlib.style.use(style)
-                try:
+                with _cleanup_cm(), matplotlib.style.context(style):
                     yield from func(*args, **kwargs)
-                finally:
-                    _do_cleanup(original_units_registry, original_settings)
         else:
             @functools.wraps(func)
             def wrapped_callable(*args, **kwargs):
-                original_units_registry = matplotlib.units.registry.copy()
-                original_settings = mpl.rcParams.copy()
-                matplotlib.style.use(style)
-                try:
+                with _cleanup_cm(), matplotlib.style.context(style):
                     func(*args, **kwargs)
-                finally:
-                    _do_cleanup(original_units_registry, original_settings)
 
         return wrapped_callable