Do not deep-reload collection to fix tests.

Will allow test of  #8464 to pass.

IPython/lib/tests/test_deepreload.py

@@ -1,53 +1,60
 # -*- coding: utf-8 -*-
 """Test suite for the deepreload module."""
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 
 import nose.tools as nt
 
 from IPython.testing import decorators as dec
-from IPython.utils.py3compat import builtin_mod_name
+from IPython.utils.py3compat import builtin_mod_name, PY3
 from IPython.utils.syspathcontext import prepended_to_syspath
 from IPython.utils.tempdir import TemporaryDirectory
 from IPython.lib.deepreload import reload as dreload
 
 #-----------------------------------------------------------------------------
 # Test functions begin
 #-----------------------------------------------------------------------------
 
 @dec.skipif_not_numpy
 def test_deepreload_numpy():
     "Test that NumPy can be deep reloaded."
     import numpy
     exclude = [
         # Standard exclusions:
         'sys', 'os.path', builtin_mod_name, '__main__',
         # Test-related exclusions:
         'unittest', 'UserDict',
         ]
+
+    # `collections` builtin shall not be reloaded to avoid failure
+    # of lib.pretty collections related pretty printing.
+    # of course this make nose crash on Py3 because of Py 2.3 compat...
+    if not PY3:
+        exclude.append('collections')
+
     dreload(numpy, exclude=exclude)
 
 def test_deepreload():
     "Test that dreload does deep reloads and skips excluded modules."
     with TemporaryDirectory() as tmpdir:
         with prepended_to_syspath(tmpdir):
             with open(os.path.join(tmpdir, 'A.py'), 'w') as f:
                 f.write("class Object(object):\n    pass\n")
             with open(os.path.join(tmpdir, 'B.py'), 'w') as f:
                 f.write("import A\n")
             import A
             import B
 
             # Test that A is not reloaded.
             obj = A.Object()
             dreload(B, exclude=['A'])
             nt.assert_true(isinstance(obj, A.Object))
 
             # Test that A is reloaded.
             obj = A.Object()
             dreload(B)
             nt.assert_false(isinstance(obj, A.Object))