Update from https://crrev.com/304121

build/android/pylib/utils/mock_calls.py

+#!/usr/bin/env python
+# Copyright 2014 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.
+
+"""
+A test facility to assert call sequences while mocking their behavior.
+"""
+
+import os
+import sys
+import unittest
+
+from pylib import constants
+
+sys.path.append(os.path.join(
+    constants.DIR_SOURCE_ROOT, 'third_party', 'pymock'))
+import mock # pylint: disable=F0401
+
+
+class TestCase(unittest.TestCase):
+  """Adds assertCalls to TestCase objects."""
+  class _AssertCalls(object):
+    def __init__(self, test_case, expected_calls, watched):
+      def call_action(pair):
+        if isinstance(pair, type(mock.call)):
+          return (pair, None)
+        else:
+          return pair
+
+      def do_check(call):
+        def side_effect(*args, **kwargs):
+          received_call = call(*args, **kwargs)
+          self._test_case.assertTrue(
+              self._expected_calls,
+              msg=('Unexpected call: %s' % str(received_call)))
+          expected_call, action = self._expected_calls.pop(0)
+          self._test_case.assertTrue(
+              received_call == expected_call,
+              msg=('Expected call missmatch:\n'
+                   '  expected: %s\n'
+                   '  received: %s\n'
+                   % (str(expected_call), str(received_call))))
+          if callable(action):
+            return action(*args, **kwargs)
+          else:
+            return action
+        return side_effect
+
+      self._test_case = test_case
+      self._expected_calls = [call_action(pair) for pair in expected_calls]
+      watched = watched.copy() # do not pollute the caller's dict
+      watched.update((call.parent.name, call.parent)
+                     for call, _ in self._expected_calls)
+      self._patched = [test_case.patch_call(call, side_effect=do_check(call))
+                       for call in watched.itervalues()]
+
+    def __enter__(self):
+      for patch in self._patched:
+        patch.__enter__()
+      return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+      for patch in self._patched:
+        patch.__exit__(exc_type, exc_val, exc_tb)
+      if exc_type is None:
+        missing = ''.join('  expected: %s\n' % str(call)
+                          for call, _ in self._expected_calls)
+        self._test_case.assertFalse(
+            missing,
+            msg='Expected calls not found:\n' + missing)
+
+  def __init__(self, *args, **kwargs):
+    super(TestCase, self).__init__(*args, **kwargs)
+    self.call = mock.call.self
+    self._watched = {}
+
+  def call_target(self, call):
+    """Resolve a self.call instance to the target it represents.
+
+    Args:
+      call: a self.call instance, e.g. self.call.adb.Shell
+
+    Returns:
+      The target object represented by the call, e.g. self.adb.Shell
+
+    Raises:
+      ValueError if the path of the call does not start with "self", i.e. the
+          target of the call is external to the self object.
+      AttributeError if the path of the call does not specify a valid
+          chain of attributes (without any calls) starting from "self".
+    """
+    path = call.name.split('.')
+    if path.pop(0) != 'self':
+      raise ValueError("Target %r outside of 'self' object" % call.name)
+    target = self
+    for attr in path:
+      target = getattr(target, attr)
+    return target
+
+  def patch_call(self, call, **kwargs):
+    """Patch the target of a mock.call instance.
+
+    Args:
+      call: a mock.call instance identifying a target to patch
+      Extra keyword arguments are processed by mock.patch
+
+    Returns:
+      A context manager to mock/unmock the target of the call
+    """
+    if call.name.startswith('self.'):
+      target = self.call_target(call.parent)
+      _, attribute = call.name.rsplit('.', 1)
+      return mock.patch.object(target, attribute, **kwargs)
+    else:
+      return mock.patch(call.name, **kwargs)
+
+  def watchCalls(self, calls):
+    """Add calls to the set of watched calls.
+
+    Args:
+      calls: a sequence of mock.call instances identifying targets to watch
+    """
+    self._watched.update((call.name, call) for call in calls)
+
+  def watchMethodCalls(self, call):
+    """Watch all public methods of the target identified by a self.call.
+
+    Args:
+      call: a self.call instance indetifying an object
+    """
+    target = self.call_target(call)
+    self.watchCalls(getattr(call, method)
+                    for method in dir(target.__class__)
+                    if not method.startswith('_'))
+
+  def clearWatched(self):
+    """Clear the set of watched calls."""
+    self._watched = {}
+
+  def assertCalls(self, *calls):
+    """A context manager to assert that a sequence of calls is made.
+
+    During the assertion, a number of functions and methods will be "watched",
+    and any calls made to them is expected to appear---in the exact same order,
+    and with the exact same arguments---as specified by the argument |calls|.
+
+    By default, the targets of all expected calls are watched. Further targets
+    to watch may be added using watchCalls and watchMethodCalls.
+
+    Optionaly, each call may be accompanied by an action. If the action is a
+    (non-callable) value, this value will be used as the return value given to
+    the caller when the matching call is found. Alternatively, if the action is
+    a callable, the action will be then called with the same arguments as the
+    intercepted call, so that it can provide a return value or perform other
+    side effects. If the action is missing, a return value of None is assumed.
+
+    Note that mock.Mock objects are often convenient to use as a callable
+    action, e.g. to raise exceptions or return other objects which are
+    themselves callable.
+
+    Args:
+      calls: each argument is either a pair (expected_call, action) or just an
+          expected_call, where expected_call is a mock.call instance.
+
+    Raises:
+      AssertionError if the watched targets do not receive the exact sequence
+          of calls specified. Missing calls, extra calls, and calls with
+          mismatching arguments, all cause the assertion to fail.
+    """
+    return self._AssertCalls(self, calls, self._watched)
+
+  def assertCall(self, call, action=None):
+    return self.assertCalls((call, action))
+