Add auto_stub mocking library.

testing_support/auto_stub.py

Index: testing_support/auto_stub.py
diff --git a/testing_support/auto_stub.py b/testing_support/auto_stub.py
new file mode 100644
index 0000000000000000000000000000000000000000..91a67af62d26013c41a8c128ee8d17e415d7f9e7
--- /dev/null
+++ b/testing_support/auto_stub.py
@@ -0,0 +1,71 @@
+# 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.
+
+import collections
+import inspect
+import unittest
+
+
+class AutoStubMixIn(object):
+  """Automatically restores stubbed functions on unit test teardDown.
+
+  It's an extremely lightweight mocking class that doesn't require bookeeping.
+  """
+  _saved = None
+
+  def mock(self, obj, member, mock):
+    self._saved = self._saved or collections.OrderedDict()
+    old_value = self._saved.setdefault(
+        obj, collections.OrderedDict()).setdefault(member, getattr(obj, member))
+    setattr(obj, member, mock)
+    return old_value
+
+  def tearDown(self):
+    """Restore all the mocked members."""
+    if self._saved:
+      for obj, items in self._saved.iteritems():
+        for member, previous_value in items.iteritems():
+          setattr(obj, member, previous_value)
+
+
+class SimpleMock(object):
+  """Really simple manual class mock."""
+  def __init__(self, unit_test):
+    """Do not call __init__ if you want to use the global call list to detect
+    ordering across different instances.
+    """
+    self.calls = []
+    self.unit_test = unit_test
+    self.assertEqual = unit_test.assertEqual
+
+  def pop_calls(self):
+    """Returns the list of calls up to date.
+
+    Good to do self.assertEqual(expected, mock.pop_calls()).
+    """
+    calls = self.calls
+    self.calls = []
+    return calls
+
+  def check_calls(self, expected):
+    self.assertEqual(expected, self.pop_calls())
+
+  def _register_call(self, *args, **kwargs):
+    """Registers the name of the caller function."""
+    caller_name = kwargs.pop('caller_name', None) or inspect.stack()[1][3]
+    str_args = ', '.join(repr(arg) for arg in args)
+    str_kwargs = ', '.join('%s=%r' % (k, v) for k, v in kwargs.iteritems())
+    self.calls.append('%s(%s)' % (
+        caller_name, ', '.join(filter(None, [str_args, str_kwargs]))))
+
+
+class TestCase(unittest.TestCase, AutoStubMixIn):
+  """Adds self.mock() and self.has_failed() to a TestCase."""
+  def tearDown(self):
+    AutoStubMixIn.tearDown(self)
+    unittest.TestCase.tearDown(self)
+
+  def has_failed(self):
+    """Returns True if the test has failed."""
+    return not self._resultForDoCleanups.wasSuccessful()