From 0a30a2046e1511c4426e5e78083e4c4f5d9c7e6c Mon Sep 17 00:00:00 2001
From: Stefan van der Walt <stefan@sun.ac.za>
Date: Sun, 24 Jun 2012 17:14:38 -0700
Subject: [PATCH] ENH: Allow resetting the plugin state.

---
 skimage/io/__init__.py             |  8 ++++++--
 skimage/io/_plugins/plugin.py      | 21 +++++++++++++++------
 skimage/io/tests/test_fits.py      |  5 +++++
 skimage/io/tests/test_freeimage.py |  4 ++++
 skimage/io/tests/test_pil.py       |  6 +++++-
 skimage/io/tests/test_plugin.py    |  5 +----
 skimage/io/tests/test_tifffile.py  |  4 +---
 7 files changed, 37 insertions(+), 16 deletions(-)

diff --git a/skimage/io/__init__.py b/skimage/io/__init__.py
index dc629be6..c5dd0b77 100644
--- a/skimage/io/__init__.py
+++ b/skimage/io/__init__.py
@@ -8,6 +8,7 @@ from ._plugins import use as use_plugin
 from ._plugins import available as plugins
 from ._plugins import info as plugin_info
 from ._plugins import configuration as plugin_order
+from ._plugins import reset_plugins as _reset_plugins
 
 from .sift import *
 from .collection import *
@@ -40,8 +41,9 @@ def _load_preferred_plugins():
     except ImportError:
         pass
 
-_load_preferred_plugins()
-
+def reset_plugins():
+    _reset_plugins()
+    _load_preferred_plugins()
 
 def _update_doc(doc):
     """Add a list of plugins to the module docstring, formatted as
@@ -72,3 +74,5 @@ def _update_doc(doc):
     return doc
 
 __doc__ = _update_doc(__doc__)
+
+reset_plugins()
diff --git a/skimage/io/_plugins/plugin.py b/skimage/io/_plugins/plugin.py
index 5ee04f1e..66ac3911 100644
--- a/skimage/io/_plugins/plugin.py
+++ b/skimage/io/_plugins/plugin.py
@@ -2,23 +2,32 @@
 
 """
 
-__all__ = ['use', 'available', 'call', 'info', 'configuration']
+__all__ = ['use', 'available', 'call', 'info', 'configuration', 'reset_plugins']
 
 import warnings
 from ConfigParser import ConfigParser
 import os.path
 from glob import glob
 
-plugin_store = {'imread': [],
-                'imsave': [],
-                'imshow': [],
-                'imread_collection': [],
-                '_app_show': []}
+plugin_store = None
 
 plugin_provides = {}
 plugin_module_name = {}
 plugin_meta_data = {}
 
+def reset_plugins():
+    """Clear the plugin state to the default, i.e., where no plugins are loaded.
+
+    """
+    global plugin_store
+    plugin_store = {'imread': [],
+                    'imsave': [],
+                    'imshow': [],
+                    'imread_collection': [],
+                    '_app_show': []}
+
+reset_plugins()
+
 def _scan_plugins():
     """Scan the plugins directory for .ini files and parse them
     to gather plugin meta-data.
diff --git a/skimage/io/tests/test_fits.py b/skimage/io/tests/test_fits.py
index 7972dd9d..bf918882 100644
--- a/skimage/io/tests/test_fits.py
+++ b/skimage/io/tests/test_fits.py
@@ -26,6 +26,11 @@ def test_fits_plugin_import():
     else:
         assert pyfits_available == True
 
+
+def teardown():
+    io.reset_plugins()
+
+
 @skipif(not pyfits_available)
 def test_imread_MEF():
     io.use_plugin('fits')
diff --git a/skimage/io/tests/test_freeimage.py b/skimage/io/tests/test_freeimage.py
index 0f598fe6..3d8d16f4 100644
--- a/skimage/io/tests/test_freeimage.py
+++ b/skimage/io/tests/test_freeimage.py
@@ -27,6 +27,10 @@ def setup_module(self):
         pass
 
 
+def teardown():
+    sio.reset_plugins()
+
+
 @skipif(not FI_available)
 def test_imread():
     img = sio.imread(os.path.join(si.data_dir, 'color.png'))
diff --git a/skimage/io/tests/test_pil.py b/skimage/io/tests/test_pil.py
index 68a21cf0..9f83fcf2 100644
--- a/skimage/io/tests/test_pil.py
+++ b/skimage/io/tests/test_pil.py
@@ -6,7 +6,7 @@ from numpy.testing.decorators import skipif
 from tempfile import NamedTemporaryFile
 
 from skimage import data_dir
-from skimage.io import imread, imsave, use_plugin
+from skimage.io import imread, imsave, use_plugin, reset_plugins
 
 try:
     from PIL import Image
@@ -18,6 +18,10 @@ else:
     PIL_available = True
 
 
+def teardown():
+    reset_plugins()
+
+
 def setup_module(self):
     """The effect of the `plugin.use` call may be overridden by later imports.
     Call `use_plugin` directly before the tests to ensure that PIL is used.
diff --git a/skimage/io/tests/test_plugin.py b/skimage/io/tests/test_plugin.py
index f801db1e..6480c922 100644
--- a/skimage/io/tests/test_plugin.py
+++ b/skimage/io/tests/test_plugin.py
@@ -4,8 +4,6 @@ from skimage import io
 from skimage.io._plugins import plugin
 from numpy.testing.decorators import skipif
 
-from copy import deepcopy
-
 try:
     io.use_plugin('pil')
     PIL_available = True
@@ -22,11 +20,10 @@ except OSError:
 
 
 def setup_module(self):
-    self.backup_plugin_store = deepcopy(plugin.plugin_store)
     plugin.use('test') # see ../_plugins/test_plugin.py
 
 def teardown_module(self):
-    plugin.plugin_store = self.backup_plugin_store
+    io.reset_plugins()
 
 class TestPlugin:
     def test_read(self):
diff --git a/skimage/io/tests/test_tifffile.py b/skimage/io/tests/test_tifffile.py
index fd03804b..0f128bf1 100644
--- a/skimage/io/tests/test_tifffile.py
+++ b/skimage/io/tests/test_tifffile.py
@@ -17,9 +17,7 @@ except ImportError:
 
 
 def teardown():
-    if TF_available:
-        for k, v in _plugins.items():
-            sio.use_plugin(v[0], k)
+    sio.reset_plugins()
 
 
 @skipif(not TF_available)