Remove null plugin since we have the pil plugin as a requirement

skimage/io/_plugins/null_plugin.ini

@@ -1,3 +0,0 @@
-[null]
-description = Default plugin that does nothing
-provides = imshow, imread, imsave, _app_show

skimage/io/_plugins/null_plugin.py

@@ -1,25 +0,0 @@
-__all__ = ['imshow', 'imread', 'imsave', '_app_show']
-
-import warnings
-
-message = '''\
-No plugin has been loaded.  Please refer to the docstring for ``skimage.io``
-for a list of available plugins.  You may specify a plugin explicitly as
-an argument to ``imread``, e.g. ``imread("image.jpg", plugin='pil')``.
-
-'''
-
-
-def imshow(*args, **kwargs):
-    warnings.warn(RuntimeWarning(message))
-
-
-def imread(*args, **kwargs):
-    warnings.warn(RuntimeWarning(message))
-
-
-def imsave(*args, **kwargs):
-    warnings.warn(RuntimeWarning(message))
-
-
-_app_show = imshow

skimage/io/manage_plugins.py

@@ -44,7 +44,7 @@ plugin_meta_data = {}
 # the following preferences.
 preferred_plugins = {
     # Default plugins for all types (overridden by specific types below).
-    'all': ['pil', 'matplotlib', 'qt', 'freeimage', 'null']
+    'all': ['pil', 'matplotlib', 'qt', 'freeimage']
 }
 
 

skimage/io/tests/test_null.py

@@ -1,50 +0,0 @@
-import os
-import warnings
-from contextlib import contextmanager
-
-import numpy as np
-from numpy.testing import raises
-
-from skimage import io
-from skimage import data_dir
-
-
-@contextmanager
-def warnings_as_errors():
-    # Temporarily set warnings as errors so we can test the warning is raised.
-    with warnings.catch_warnings():
-        warnings.filterwarnings('error')
-        yield
-
-@raises(Warning)
-def test_null_imread():
-    path = os.path.join(data_dir, 'color.png')
-    with warnings_as_errors():
-        io.imread(path, plugin='null')
-
-
-@raises(Warning)
-def test_null_imsave():
-    with warnings_as_errors():
-        io.imsave('dummy.png', np.zeros((3, 3)), plugin='null')
-
-
-@raises(Warning)
-def test_null_imshow():
-    with warnings_as_errors():
-        io.imshow(np.zeros((3, 3)), plugin='null')
-
-
-@raises(Warning)
-def test_null_imread_collection():
-    # Note that the null plugin doesn't define an `imread_collection` plugin
-    # but this function is dynamically added by the plugin manager.
-    path = os.path.join(data_dir, '*.png')
-    with warnings_as_errors():
-        collection = io.imread_collection(path, plugin='null')
-        collection[0]
-
-
-if __name__ == '__main__':
-    from numpy.testing import run_module_suite
-    run_module_suite()