Make subprocess2.Popen a class instead of a function.

tests/subprocess2_test.py

 #!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Unit tests for subprocess2.py."""
 
 import logging
 import optparse
 import os
@@ skipping 29 matching lines @@
   if sys.platform == 'win32':
     return string.replace('\n', '\r\n')
   return string
 
 
 class DefaultsTest(unittest.TestCase):
   # Can be mocked in a test.
   TO_SAVE = {
     subprocess2: [
       'Popen', 'communicate', 'call', 'check_call', 'capture', 'check_output'],
-    subprocess2.subprocess: ['Popen'],
+    subprocess2.subprocess.Popen: ['__init__', 'communicate'],
   }
 
   def setUp(self):
     self.saved = {}
     for module, names in self.TO_SAVE.iteritems():
       self.saved[module] = dict(
           (name, getattr(module, name)) for name in names)
     # TODO(maruel): Do a reopen() on sys.__stdout__ and sys.__stderr__ so they
     # can be trapped in the child process for better coverage.
 
   def tearDown(self):
     for module, saved in self.saved.iteritems():
       for name, value in saved.iteritems():
         setattr(module, name, value)
 
   @staticmethod
   def _fake_communicate():
+    """Mocks subprocess2.communicate()."""
     results = {}
     def fake_communicate(args, **kwargs):
       assert not results
       results.update(kwargs)
       results['args'] = args
-      return ['stdout', 'stderr'], 0
+      return ('stdout', 'stderr'), 0
     subprocess2.communicate = fake_communicate
     return results
 
   @staticmethod
   def _fake_Popen():
+    """Mocks the whole subprocess2.Popen class."""
     results = {}
     class fake_Popen(object):
       returncode = -8
       def __init__(self, args, **kwargs):
         assert not results
         results.update(kwargs)
         results['args'] = args
       @staticmethod
       def communicate():
         return None, None
     subprocess2.Popen = fake_Popen
     return results
 
   @staticmethod
   def _fake_subprocess_Popen():
+    """Mocks the base class subprocess.Popen only."""
     results = {}
-    class fake_Popen(object):
-      returncode = -8
-      def __init__(self, args, **kwargs):
-        assert not results
-        results.update(kwargs)
-        results['args'] = args
-      @staticmethod
-      def communicate():
-        return None, None
-    subprocess2.subprocess.Popen = fake_Popen
+    def __init__(self, args, **kwargs):
+      assert not results
+      results.update(kwargs)
+      results['args'] = args
+    def communicate():
+      return None, None
+    subprocess2.subprocess.Popen.__init__ = __init__
+    subprocess2.subprocess.Popen.communicate = communicate
     return results
 
   def test_check_call_defaults(self):
     results = self._fake_communicate()
     self.assertEquals(
-        ['stdout', 'stderr'], subprocess2.check_call_out(['foo'], a=True))
+        ('stdout', 'stderr'), subprocess2.check_call_out(['foo'], a=True))
     expected = {
         'args': ['foo'],
         'a':True,
     }
     self.assertEquals(expected, results)
 
   def test_capture_defaults(self):
     results = self._fake_communicate()
     self.assertEquals(
         'stdout', subprocess2.capture(['foo'], a=True))
@@ skipping 11 matching lines @@
         ((None, None), -8), subprocess2.communicate(['foo'], a=True))
     expected = {
         'args': ['foo'],
         'a': True,
     }
     self.assertEquals(expected, results)
 
   def test_Popen_defaults(self):
     results = self._fake_subprocess_Popen()
     proc = subprocess2.Popen(['foo'], a=True)
-    self.assertEquals(-8, proc.returncode)
+    # Cleanup code in subprocess.py needs this member to be set.
+    # pylint: disable=W0201
+    proc._child_created = None
+    # Since subprocess.Popen.__init__() is not called, proc.returncode shouldn't
+    # be present.
+    self.assertFalse(hasattr(proc, 'returncode'))
     expected = {
         'args': ['foo'],
         'a': True,
         'shell': bool(sys.platform=='win32'),
     }
     if sys.platform != 'win32':
       env = os.environ.copy()
       is_english = lambda name: env.get(name, 'en').startswith('en')
       if not is_english('LANG'):
         env['LANG'] = 'en_US.UTF-8'
@@ skipping 213 matching lines @@
   return options.return_value
 
 
 if __name__ == '__main__':
   logging.basicConfig(level=
       [logging.WARNING, logging.INFO, logging.DEBUG][
         min(2, sys.argv.count('-v'))])
   if len(sys.argv) > 1 and sys.argv[1] == '--child':
     sys.exit(child_main(sys.argv[2:]))
   unittest.main()