Fix memory leaks in the test suite.

This works by avoiding storing a reference to the figure in the
"do_test" enclosure in the image_comparison decorator.  nose keeps a
reference to all of its test functions, and thereby holds on to every
figure in every test that uses the image_comparison decorator (which is
most).  Instead of using the figure in the outer scope, this just uses
the figure number, and then it's looked up when the test function is
actually run.

Also adds gc.collect() so we can ensure there are zero figures in memory
at the start of each test.  Probably not strictly necessary, but it
makes analysing memory usage easier.

Author: mdboom

lib/matplotlib/testing/decorators.py

@@ -4,6 +4,7 @@
 import six
 
 import functools
+import gc
 import os
 import sys
 import shutil
@@ -65,20 +66,25 @@ def failer(*args, **kwargs):
     return known_fail_decorator
 
 
+def _do_cleanup(original_units_registry):
+    plt.close('all')
+    gc.collect()
+
+    matplotlib.tests.setup()
+
+    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()
 
     @classmethod
     def teardown_class(cls):
-        plt.close('all')
-
-        matplotlib.tests.setup()
-
-        matplotlib.units.registry.clear()
-        matplotlib.units.registry.update(cls.original_units_registry)
-        warnings.resetwarnings()  # reset any warning filters set in tests
+        _do_cleanup(cls.original_units_registry)
 
     def test(self):
         self._func()
@@ -93,13 +99,7 @@ def setUpClass(cls):
 
     @classmethod
     def tearDownClass(cls):
-        plt.close('all')
-
-        matplotlib.tests.setup()
-
-        matplotlib.units.registry.clear()
-        matplotlib.units.registry.update(cls.original_units_registry)
-        warnings.resetwarnings()  # reset any warning filters set in tests
+        _do_cleanup(cls.original_units_registry)
 
 
 def cleanup(func):
@@ -109,13 +109,8 @@ def wrapped_function(*args, **kwargs):
         try:
             func(*args, **kwargs)
         finally:
-            plt.close('all')
-
-            matplotlib.tests.setup()
+            _do_cleanup(original_units_registry)
 
-            matplotlib.units.registry.clear()
-            matplotlib.units.registry.update(original_units_registry)
-            warnings.resetwarnings() #reset any warning filters set in tests
     return wrapped_function
 
 
@@ -157,8 +152,6 @@ def test(self):
         baseline_dir, result_dir = _image_directories(self._func)
 
         for fignum, baseline in zip(plt.get_fignums(), self._baseline_images):
-            figure = plt.figure(fignum)
-
             for extension in self._extensions:
                 will_fail = not extension in comparable_formats()
                 if will_fail:
@@ -182,6 +175,8 @@ def test(self):
                     will_fail, fail_msg,
                     known_exception_class=ImageComparisonFailure)
                 def do_test():
+                    figure = plt.figure(fignum)
+
                     if self._remove_text:
                         self.remove_text(figure)
 

test_only.py

@@ -0,0 +1,18 @@
+from distutils.core import setup
+
+import os
+
+baseline_images = [
+    'baseline_images/%s/*' % x
+    for x in os.listdir('lib/matplotlib/tests/baseline_images')]
+
+baseline_images += [
+        'mpltest.ttf',
+        'test_rcparams.rc'
+    ]
+
+setup(name='matplotlib.tests',
+      packages=['matplotlib.tests'],
+      package_dir={'matplotlib.tests': 'lib/matplotlib/tests'},
+      package_data={'matplotlib.tests': baseline_images}
+)