Fixing test failures.

Author: Ben Cipollini

nibabel/testing/__init__.py

@@ -9,6 +9,7 @@
 ''' Utilities for testing '''
 from __future__ import division, print_function
 
+import sys
 import warnings
 from os.path import dirname, abspath, join as pjoin
 
@@ -56,6 +57,16 @@ def assert_allclose_safely(a, b, match_nans=True):
     assert_true(np.allclose(a, b))
 
 
+def get_fresh_mod(mod_name=__name__):
+    # Get this module, with warning registry empty
+    my_mod = sys.modules[mod_name]
+    try:
+        my_mod.__warningregistry__.clear()
+    except AttributeError:
+        pass
+    return my_mod
+
+
 class clear_and_catch_warnings(warnings.catch_warnings):
     """ Context manager that resets warning registry for catching warnings
 

nibabel/tests/test_checkwarns.py

@@ -3,24 +3,19 @@
 from __future__ import division, print_function, absolute_import
 
 from nose.tools import assert_true, assert_equal, assert_raises
-from ..testing import (error_warnings, suppress_warnings,
-                       clear_and_catch_warnings)
+from ..testing import clear_and_catch_warnings, suppress_warnings
 
 
 def test_ignore_and_error_warnings():
-    with clear_and_catch_warnings() as w:
-        from ..checkwarns import ErrorWarnings, IgnoreWarnings
-        assert_equal(len(w), 1)
-        assert_equal(w[0].category, FutureWarning)
+    with suppress_warnings():
+        from .. import checkwarns
 
     with clear_and_catch_warnings() as w:
-        with IgnoreWarnings():
-            pass
+        checkwarns.IgnoreWarnings()
         assert_equal(len(w), 1)
         assert_equal(w[0].category, FutureWarning)
 
     with clear_and_catch_warnings() as w:
-        with ErrorWarnings():
-            pass
+        checkwarns.ErrorWarnings()
         assert_equal(len(w), 1)
         assert_equal(w[0].category, FutureWarning)

nibabel/tests/test_testing.py

@@ -3,13 +3,14 @@
 from __future__ import division, print_function, absolute_import
 
 import sys
-from warnings import warn, simplefilter, filters
+import warnings
 
 import numpy as np
 
 from nose.tools import assert_true, assert_equal, assert_raises
 from ..testing import (error_warnings, suppress_warnings,
-                       clear_and_catch_warnings, assert_allclose_safely)
+                       clear_and_catch_warnings, assert_allclose_safely,
+                       get_fresh_mod)
 
 
 def assert_warn_len_equal(mod, n_in_context):
@@ -60,9 +61,21 @@ def test_assert_allclose_safely():
     assert_allclose_safely([], [])
 
 
+def assert_warn_len_equal(mod, n_in_context):
+    mod_warns = mod.__warningregistry__
+    # Python 3.4 appears to clear any pre-existing warnings of the same type,
+    # when raising warnings inside a catch_warnings block. So, there is a
+    # warning generated by the tests within the context manager, but no
+    # previous warnings.
+    if 'version' in mod_warns:
+        assert_equal(len(mod_warns), 2)  # including 'version'
+    else:
+        assert_equal(len(mod_warns), n_in_context)
+
+
 def test_clear_and_catch_warnings():
     # Initial state of module, no warnings
-    my_mod = _get_fresh_mod()
+    my_mod = get_fresh_mod(__name__)
     assert_equal(getattr(my_mod, '__warningregistry__', {}), {})
     with clear_and_catch_warnings(modules=[my_mod]):
         warnings.simplefilter('ignore')
@@ -92,7 +105,7 @@ class my_cacw(clear_and_catch_warnings):
 
 def test_clear_and_catch_warnings_inherit():
     # Test can subclass and add default modules
-    my_mod = _get_fresh_mod()
+    my_mod = get_fresh_mod(__name__)
     with my_cacw():
         warnings.simplefilter('ignore')
         warnings.warn('Some warning')
@@ -101,12 +114,12 @@ def test_clear_and_catch_warnings_inherit():
 
 def test_warn_error():
     # Check warning error context manager
-    n_warns = len(filters)
+    n_warns = len(warnings.filters)
     with error_warnings():
-        assert_raises(UserWarning, warn, 'A test')
+        assert_raises(UserWarning, warnings.warn, 'A test')
     with error_warnings() as w: # w not used for anything
-        assert_raises(UserWarning, warn, 'A test')
-    assert_equal(n_warns, len(filters))
+        assert_raises(UserWarning, warnings.warn, 'A test')
+    assert_equal(n_warns, len(warnings.filters))
     # Check other errors are propagated
     def f():
         with error_warnings():
@@ -116,14 +129,14 @@ def f():
 
 def test_warn_ignore():
     # Check warning ignore context manager
-    n_warns = len(filters)
+    n_warns = len(warnings.filters)
     with suppress_warnings():
-        warn('Here is a warning, you will not see it')
-        warn('Nor this one', DeprecationWarning)
+        warnings.warn('Here is a warning, you will not see it')
+        warnings.warn('Nor this one', DeprecationWarning)
     with suppress_warnings() as w: # w not used
-        warn('Here is a warning, you will not see it')
-        warn('Nor this one', DeprecationWarning)
-    assert_equal(n_warns, len(filters))
+        warnings.warn('Here is a warning, you will not see it')
+        warnings.warn('Nor this one', DeprecationWarning)
+    assert_equal(n_warns, len(warnings.filters))
     # Check other errors are propagated
     def f():
         with suppress_warnings():