Better code isolation in tests.

IPython/frontend/tests/test_prefilterfrontend.py

@@ -1,177 +1,180 b''
 # encoding: utf-8
 """
 Test process execution and IO redirection.
 """
 
 __docformat__ = "restructuredtext en"
 
 #-------------------------------------------------------------------------------
 #  Copyright (C) 2008  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is
 #  in the file COPYING, distributed as part of this software.
 #-------------------------------------------------------------------------------
 
 from cStringIO import StringIO
 import string
 
 from IPython.ipapi import get as get_ipython0
 from IPython.frontend.prefilterfrontend import PrefilterFrontEnd
+from copy import deepcopy
 
 class TestPrefilterFrontEnd(PrefilterFrontEnd):
     
     input_prompt_template = string.Template('')
     output_prompt_template = string.Template('')
     banner = ''
 
     def __init__(self):
         ipython0 = get_ipython0().IP
         self.out = StringIO()
         PrefilterFrontEnd.__init__(self, ipython0=ipython0)
         # Clean up the namespace for isolation between tests
         user_ns = self.ipython0.user_ns
         # We need to keep references to things so that they don't
         # get garbage collected (this stinks).
         self.shadow_ns = dict()
         for i in self.ipython0.magic_who_ls():
             self.shadow_ns[i] = user_ns.pop(i)
         # Some more code for isolation (yeah, crazy)
         self._on_enter()
         self.out.flush()
         self.out.reset()
         self.out.truncate()
 
     def write(self, string, *args, **kwargs):
        self.out.write(string) 
 
     def _on_enter(self):
         self.input_buffer += '\n'
         PrefilterFrontEnd._on_enter(self)
 
 
 def isolate_ipython0(func):
     """ Decorator to isolate execution that involves an iptyhon0.
     """
     def my_func(*args, **kwargs):
         ipython0 = get_ipython0().IP
-        user_ns = ipython0.user_ns
-        global_ns = ipython0.global_ns
-        func(*args, **kwargs)
-        ipython0.user_ns = user_ns
-        ipython0.global_ns = global_ns
+        user_ns = deepcopy(ipython0.user_ns)
+        global_ns = deepcopy(ipython0.global_ns)
+        try:
+            func(*args, **kwargs)
+        finally:
+            ipython0.user_ns = user_ns
+            ipython0.global_ns = global_ns
 
     return my_func
 
 
 @isolate_ipython0
 def test_execution():
     """ Test execution of a command.
     """
     f = TestPrefilterFrontEnd()
     f.input_buffer = 'print 1'
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value  == '1\n'
 
 
 @isolate_ipython0
 def test_multiline():
     """ Test execution of a multiline command.
     """
     f = TestPrefilterFrontEnd()
     f.input_buffer = 'if True:'
     f._on_enter()
     f.input_buffer += 'print 1'
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value == ''
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value == '1\n'
     f = TestPrefilterFrontEnd()
     f.input_buffer='(1 +'
     f._on_enter()
     f.input_buffer += '0)'
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value == ''
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value == '1\n'
 
 
 @isolate_ipython0
 def test_capture():
     """ Test the capture of output in different channels.
     """
     # Test on the OS-level stdout, stderr.
     f = TestPrefilterFrontEnd()
     f.input_buffer = \
             'import os; out=os.fdopen(1, "w"); out.write("1") ; out.flush()'
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value == '1'
     f = TestPrefilterFrontEnd()
     f.input_buffer = \
             'import os; out=os.fdopen(2, "w"); out.write("1") ; out.flush()'
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value == '1'
 
      
 @isolate_ipython0
 def test_magic():
     """ Test the magic expansion and history.
     
         This test is fairly fragile and will break when magics change.
     """
     f = TestPrefilterFrontEnd()
     f.input_buffer += '%who'
     f._on_enter()
     out_value = f.out.getvalue()
     assert out_value == 'Interactive namespace is empty.\n'
 
 
 @isolate_ipython0
 def test_help():
     """ Test object inspection.
     """
     f = TestPrefilterFrontEnd()
     f.input_buffer += "def f():"
     f._on_enter()
     f.input_buffer += "'foobar'"
     f._on_enter()
     f.input_buffer += "pass"
     f._on_enter()
     f._on_enter()
     f.input_buffer += "f?"
     f._on_enter()
     assert 'traceback' not in f.last_result
     ## XXX: ipython doctest magic breaks this. I have no clue why
     #out_value = f.out.getvalue()
     #assert out_value.split()[-1] == 'foobar' 
 
 
 @isolate_ipython0
 def test_completion():
     """ Test command-line completion.
     """
     f = TestPrefilterFrontEnd()
     f.input_buffer = 'zzza = 1'
     f._on_enter()
     f.input_buffer = 'zzzb = 2'
     f._on_enter()
     f.input_buffer = 'zz'
     f.complete_current_input()
     out_value = f.out.getvalue()
     assert out_value == '\nzzza zzzb '
     assert f.input_buffer == 'zzz'
 
 
 if __name__ == '__main__':
     test_magic()
     test_help()
     test_execution()
     test_multiline()
     test_capture()
     test_completion()