blob: 78fdd47972f03cc5d20e4cb2353f722163057b44 [file] [log] [blame]
# 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 unittest
from devil import devil_env
with devil_env.SysPath(devil_env.PYMOCK_PATH):
import mock # pylint: disable=import-error
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(
return (pair, None)
return pair
def do_check(call):
def side_effect(*args, **kwargs):
received_call = call(*args, **kwargs)
msg=('Unexpected call: %s' % str(received_call)))
expected_call, action = self._expected_calls.pop(0)
received_call == expected_call,
msg=('Expected call mismatch:\n'
' expected: %s\n'
' received: %s\n' % (str(expected_call),
if callable(action):
return action(*args, **kwargs)
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
(, call.parent) for call, _ in self._expected_calls)
self._patched = [
test_case.patch_call(call, side_effect=do_check(call))
for call in watched.values()
def __enter__(self):
for patch in self._patched:
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)
missing, msg='Expected calls not found:\n' + missing)
def __init__(self, *args, **kwargs):
super(TestCase, self).__init__(*args, **kwargs) =
self._watched = {}
def call_target(self, call):
"""Resolve a instance to the target it represents.
call: a instance, e.g.
The target object represented by the call, e.g. self.adb.Shell
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 ='.')
if path.pop(0) != 'self':
raise ValueError("Target %r outside of 'self' object" %
target = self
for attr in path:
target = getattr(target, attr)
return target
def patch_call(self, call, **kwargs):
"""Patch the target of a instance.
call: a instance identifying a target to patch
Extra keyword arguments are processed by mock.patch
A context manager to mock/unmock the target of the call
target = self.call_target(call.parent)
_, attribute ='.', 1)
if (hasattr(type(target), attribute)
and isinstance(getattr(type(target), attribute), property)):
return mock.patch.object(
type(target), attribute, new_callable=mock.PropertyMock, **kwargs)
return mock.patch.object(target, attribute, **kwargs)
return mock.patch(, **kwargs)
def watchCalls(self, calls):
"""Add calls to the set of watched calls.
calls: a sequence of instances identifying targets to watch
self._watched.update((, call) for call in calls)
def watchMethodCalls(self, call, ignore=None):
"""Watch all public methods of the target identified by a
call: a instance indetifying an object
ignore: a list of public methods to ignore when watching for calls
target = self.call_target(call)
if ignore is None:
ignore = []
getattr(call, method) for method in dir(target.__class__)
if not method.startswith('_') and not method in ignore)
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.
calls: each argument is either a pair (expected_call, action) or just an
expected_call, where expected_call is a instance.
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))