BUG: Make sure numpy globals keep identity after reload.

Reloading currently causes problems because global classes defined in
numpy/__init__.py change their identity (a is b) after reload. The
solution taken here is to move those classes to a new non-reloadable
module numpy/_globals and import them into numpy from there.

Classes moved are ModuleDeprecationWarning, VisibleDeprecationWarning,
and _NoValue.

Closes #7844.

1 files changed, 11 insertions, 3 deletions

diff --git a/numpy/tests/test_reloading.py b/numpy/tests/test_reloading.py
index 141e11f6c..ca651c874 100644
--- a/numpy/tests/test_reloading.py
+++ b/numpy/tests/test_reloading.py
@@ -2,7 +2,6 @@ from __future__ import division, absolute_import, print_function
 
 import sys
 
-import numpy as np
 from numpy.testing import assert_raises, assert_, run_module_suite
 
 if sys.version_info[:2] >= (3, 4):
@@ -10,13 +9,22 @@ if sys.version_info[:2] >= (3, 4):
 else:
     from imp import reload
 
-def test_reloading_exception():
+def test_numpy_reloading():
     # gh-7844. Also check that relevant globals retain their identity.
+    import numpy as np
+    import numpy._globals
+
     _NoValue = np._NoValue
     VisibleDeprecationWarning = np.VisibleDeprecationWarning
     ModuleDeprecationWarning = np.ModuleDeprecationWarning
 
-    assert_raises(RuntimeError, reload, np)
+    reload(np)
+    assert_(_NoValue is np._NoValue)
+    assert_(ModuleDeprecationWarning is np.ModuleDeprecationWarning)
+    assert_(VisibleDeprecationWarning is np.VisibleDeprecationWarning)
+
+    assert_raises(RuntimeError, reload, numpy._globals)
+    reload(np)
     assert_(_NoValue is np._NoValue)
     assert_(ModuleDeprecationWarning is np.ModuleDeprecationWarning)
     assert_(VisibleDeprecationWarning is np.VisibleDeprecationWarning)