唯快不破：mock源码剖析
有时，你需要为单元测试的初始设置准备一些“其他”的代码资源。但这些资源兴许会不可用，不稳定，或者是使用起来太笨重。你可以试着找一些其他的资源替代；或者你可以通过创建一个被称为mock的东西来模拟它。Mocks能够让我们模拟那些在单元测试中不可用或太笨重的资源。总之就是mock可以屏蔽一些我们不需要关系的细节。
mock.py
# mock.py
# Test tools for mocking and patching.
# E-mail: fuzzyman AT voidspace DOT org DOT uk
#
# mock 1.0.1
# http://www.voidspace.org.uk/python/mock/
#
# Copyright (c) 2007-2013, Michael Foord & the mock team
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
from __future__ import absolute_import
__all__ = (
'__version__',
'version_info',
'Mock',
'MagicMock',
'patch',
'sentinel',
'DEFAULT',
'ANY',
'call',
'create_autospec',
'FILTER_DIR',
'CallableMixin',
'NonCallableMock',
'NonCallableMagicMock',
'mock_open',
'PropertyMock',
)
from functools import partial
import inspect
import pprint
import sys
try:
import builtins
except ImportError:
import __builtin__ as builtins
from types import ModuleType
import six
from six import wraps
from pbr.version import VersionInfo
_v = VersionInfo('mock').semantic_version()
__version__ = _v.release_string()
version_info = _v.version_tuple()
import mock
try:
inspectsignature = inspect.signature
except AttributeError:
import funcsigs
inspectsignature = funcsigs.signature
# TODO: use six.
try:
unicode
except NameError:
# Python 3
basestring = unicode = str
try:
long
except NameError:
# Python 3
long = int
try:
BaseException
except NameError:
# Python 2.4 compatibility
BaseException = Exception
if six.PY2:
# Python 2's next() can't handle a non-iterator with a __next__ method.
_next = next
def next(obj, _next=_next):
if getattr(obj, '__next__', None):
return obj.__next__()
return _next(obj)
del _next
_builtins = set(name for name in dir(builtins) if not name.startswith('_'))
BaseExceptions = (BaseException,)
if 'java' in sys.platform:
# jython
import java
BaseExceptions = (BaseException, java.lang.Throwable)
try:
_isidentifier = str.isidentifier
except AttributeError:
# Python 2.X
import keyword
import re
regex = re.compile(r'^[a-z_][a-z0-9_]*$', re.I)
def _isidentifier(string):
if string in keyword.kwlist:
return False
return regex.match(string)
self = 'im_self'
builtin = '__builtin__'
if six.PY3:
self = '__self__'
builtin = 'builtins'
# NOTE: This FILTER_DIR is not used. The binding in mock.FILTER_DIR is.
FILTER_DIR = True
# Workaround for Python issue #12370
# Without this, the __class__ properties wouldn't be set correctly
_safe_super = super
def _is_instance_mock(obj):
# can't use isinstance on Mock objects because they override __class__
# The base class for all mocks is NonCallableMock
return issubclass(type(obj), NonCallableMock)
def _is_exception(obj):
return (
isinstance(obj, BaseExceptions) or
isinstance(obj, ClassTypes) and issubclass(obj, BaseExceptions)
)
class _slotted(object):
__slots__ = ['a']
DescriptorTypes = (
type(_slotted.a),
property,
)
def _get_signature_object(func, as_instance, eat_self):
"""
获取任何可调用对象的签名对象.
Given an arbitrary, possibly callable object, try to create a suitable
signature object.
Return a (reduced func, signature) tuple, or None.
"""
if isinstance(func, ClassTypes) and not as_instance:
# 如果是类型，就返回__init__方法签名
# If it's a type and should be modelled as a type, use __init__.
try:
func = func.__init__
except AttributeError:
return None
# Skip the `self` argument in __init__
# 跳过self参数
eat_self = True
elif not isinstance(func, FunctionTypes):
# 不是方法的其他对象都返回__call__方法签名
# If we really want to model an instance of the passed type,
# __call__ should be looked up, not __init__.
try:
func = func.__call__
except AttributeError:
return None
if eat_self:
# 跳过self
sig_func = partial(func, None)
else:
sig_func = func
try:
return func, inspectsignature(sig_func)
except ValueError:
# Certain callable types are not supported by inspect.signature()
return None
def _check_signature(func, mock, skipfirst, instance=False):
# 为mock对象设置方法签名检查方法
sig = _get_signature_object(func, instance, skipfirst)
if sig is None:
return
func, sig = sig
def checksig(_mock_self, *args, **kwargs):
# 执行函数签名检查
sig.bind(*args, **kwargs)
# 拷贝方法其他元信息
_copy_func_details(func, checksig)
type(mock)._mock_check_sig = checksig
def _copy_func_details(func, funcopy):
u"""拷贝方法元信息"""
funcopy.__name__ = func.__name__
funcopy.__doc__ = func.__doc__
try:
funcopy.__text_signature__ = func.__text_signature__
except AttributeError:
pass
# we explicitly don't copy func.__dict__ into this copy as it would
# expose original attributes that should be mocked
try:
funcopy.__module__ = func.__module__
except AttributeError:
pass
try:
funcopy.__defaults__ = func.__defaults__
except AttributeError:
pass
try:
funcopy.__kwdefaults__ = func.__kwdefaults__
except AttributeError:
pass
if six.PY2:
funcopy.func_defaults = func.func_defaults
return
def _callable(obj):
if isinstance(obj, ClassTypes):
return True
if getattr(obj, '__call__', None) is not None:
return True
return False
def _is_list(obj):
# checks for list or tuples
# XXXX badly named!
return type(obj) in (list, tuple)
def _instance_callable(obj):
"""Given an object, return True if the object is callable.
For classes, return True if instances would be callable."""
if not isinstance(obj, ClassTypes):
# already an instance
return getattr(obj, '__call__', None) is not None
if six.PY3:
# *could* be broken by a class overriding __mro__ or __dict__ via
# a metaclass
for base in (obj,) + obj.__mro__:
if base.__dict__.get('__call__') is not None:
return True
else:
klass = obj
# uses __bases__ instead of __mro__ so that we work with old style classes
if klass.__dict__.get('__call__') is not None:
return True
for base in klass.__bases__:
if _instance_callable(base):
return True
return False
def _set_signature(mock, original, instance=False):
# 封装mock对象为带签名检查的函数对象
# creates a function with signature (*args, **kwargs) that delegates to a
# mock. It still does signature checking by calling a lambda with the same
# signature as the original.
if not _callable(original):
return
skipfirst = isinstance(original, ClassTypes)
result = _get_signature_object(original, instance, skipfirst)
if result is None:
return
func, sig = result
def checksig(*args, **kwargs):
sig.bind(*args, **kwargs)
_copy_func_details(func, checksig)
name = original.__name__
if not _isidentifier(name):
# 与关键字重名
name = 'funcopy'
context = {'_checksig_': checksig, 'mock': mock}
src = """def %s(*args, **kwargs):
_checksig_(*args, **kwargs)
return mock(*args, **kwargs)""" % name
six.exec_(src, context)
funcopy = context[name]
_setup_func(funcopy, mock)
return funcopy
def _setup_func(funcopy, mock):
funcopy.mock = mock
# can't use isinstance with mocks
if not _is_instance_mock(mock):
return
def assert_called_with(*args, **kwargs):
return mock.assert_called_with(*args, **kwargs)
def assert_called_once_with(*args, **kwargs):
return mock.assert_called_once_with(*args, **kwargs)
def assert_has_calls(*args, **kwargs):
return mock.assert_has_calls(*args, **kwargs)
def assert_any_call(*args, **kwargs):
return mock.assert_any_call(*args, **kwargs)
def reset_mock():
funcopy.method_calls = _CallList()
funcopy.mock_calls = _CallList()
mock.reset_mock()
ret = funcopy.return_value
if _is_instance_mock(ret) and not ret is mock:
ret.reset_mock()
funcopy.called = False
funcopy.call_count = 0
funcopy.call_args = None
funcopy.call_args_list = _CallList()
funcopy.method_calls = _CallList()
funcopy.mock_calls = _CallList()
funcopy.return_value = mock.return_value
funcopy.side_effect = mock.side_effect
funcopy._mock_children = mock._mock_children
funcopy.assert_called_with = assert_called_with
funcopy.assert_called_once_with = assert_called_once_with
funcopy.assert_has_calls = assert_has_calls
funcopy.assert_any_call = assert_any_call
funcopy.reset_mock = reset_mock
mock._mock_delegate = funcopy
def _is_magic(name):
return '__%s__' % name[2:-2] == name
class _SentinelObject(object):
"""哨兵对象"""
"A unique, named, sentinel object."
def __init__(self, name):
self.name = name
def __repr__(self):
return 'sentinel.%s' % self.name
class _Sentinel(object):
"""Access attributes to return a named object, usable as a sentinel."""
def __init__(self):
self._sentinels = {}
def __getattr__(self, name):
"""通过访问属性返回一个命名的哨兵对象"""
if name == '__bases__':
# Without this help(unittest.mock) raises an exception
raise AttributeError
return self._sentinels.setdefault(name, _SentinelObject(name))
sentinel = _Sentinel()
DEFAULT = sentinel.DEFAULT
_missing = sentinel.MISSING
_deleted = sentinel.DELETED
class OldStyleClass:
pass
ClassType = type(OldStyleClass)
def _copy(value):
if type(value) in (dict, list, tuple, set):
return type(value)(value)
return value
ClassTypes = (type,)
if six.PY2:
ClassTypes = (type, ClassType)
_allowed_names = set((
'return_value', '_mock_return_value', 'side_effect',
'_mock_side_effect', '_mock_parent', '_mock_new_parent',
'_mock_name', '_mock_new_name'
))
def _delegating_property(name):
_allowed_names.add(name)
_the_name = '_mock_' + name
def _get(self, name=name, _the_name=_the_name):
sig = self._mock_delegate
if sig is None:
return getattr(self, _the_name)
return getattr(sig, name)
def _set(self, value, name=name, _the_name=_the_name):
sig = self._mock_delegate
if sig is None:
self.__dict__[_the_name] = value
else:
setattr(sig, name, value)
return property(_get, _set)
class _CallList(list):
def __contains__(self, value):
if not isinstance(value, list):
return list.__contains__(self, value)
len_value = len(value)
len_self = len(self)
if len_value > len_self:
return False
for i in range(0, len_self - len_value + 1):
sub_list = self[i:i+len_value]
if sub_list == value:
return True
return False
def __repr__(self):
return pprint.pformat(list(self))
def _check_and_set_parent(parent, value, name, new_name):
if not _is_instance_mock(value):
return False
if ((value._mock_name or value._mock_new_name) or
(value._mock_parent is not None) or
(value._mock_new_parent is not None)):
return False
_parent = parent
while _parent is not None:
# setting a mock (value) as a child or return value of itself
# should not modify the mock
if _parent is value:
return False
_parent = _parent._mock_new_parent
if new_name:
value._mock_new_parent = parent
value._mock_new_name = new_name
if name:
value._mock_parent = parent
value._mock_name = name
return True
# Internal class to identify if we wrapped an iterator object or not.
class _MockIter(object):
def __init__(self, obj):
self.obj = iter(obj)
def __iter__(self):
return self
def __next__(self):
return next(self.obj)
class Base(object):
_mock_return_value = DEFAULT
_mock_side_effect = None
def __init__(self, *args, **kwargs):
pass
class NonCallableMock(Base):
u"""不可以直接调用的mock类."""
"""A non-callable version of `Mock`"""
def __new__(cls, *args, **kw):
u"""以name创建一个类，并返回新实例.所以mock对象直接不会相互影响."""
# every instance has its own class
# so we can create magic methods on the
# class without stomping on other mocks
new = type(cls.__name__, (cls,), {'__doc__': cls.__doc__})
instance = object.__new__(new)
return instance
def __init__(
self, spec=None, wraps=None, name=None, spec_set=None,
parent=None, _spec_state=None, _new_name='', _new_parent=None,
_spec_as_instance=False, _eat_self=None, unsafe=False, **kwargs
):
if _new_parent is None:
_new_parent = parent
__dict__ = self.__dict__
__dict__['_mock_parent'] = parent
__dict__['_mock_name'] = name
__dict__['_mock_new_name'] = _new_name
__dict__['_mock_new_parent'] = _new_parent
if spec_set is not None:
spec = spec_set
spec_set = True
if _eat_self is None:
_eat_self = parent is not None
# 添加spec mock方法
self._mock_add_spec(spec, spec_set, _spec_as_instance, _eat_self)
__dict__['_mock_children'] = {}
__dict__['_mock_wraps'] = wraps
__dict__['_mock_delegate'] = None
__dict__['_mock_called'] = False
__dict__['_mock_call_args'] = None
__dict__['_mock_call_count'] = 0
__dict__['_mock_call_args_list'] = _CallList()
__dict__['_mock_mock_calls'] = _CallList()
__dict__['method_calls'] = _CallList()
__dict__['_mock_unsafe'] = unsafe
if kwargs:
# 配置mock对象
self.configure_mock(**kwargs)
_safe_super(NonCallableMock, self).__init__(
spec, wraps, name, spec_set, parent,
_spec_state
)
def attach_mock(self, mock, attribute):
"""
Attach a mock as an attribute of this one, replacing its name and
parent. Calls to the attached mock will be recorded in the
`method_calls` and `mock_calls` attributes of this one."""
mock._mock_parent = None
mock._mock_new_parent = None
mock._mock_name = ''
mock._mock_new_name = None
setattr(self, attribute, mock)
def mock_add_spec(self, spec, spec_set=False):
"""Add a spec to a mock. `spec` can either be an object or a
list of strings. Only attributes on the `spec` can be fetched as
attributes from the mock.
If `spec_set` is True then only attributes on the spec can be set."""
self._mock_add_spec(spec, spec_set)
def _mock_add_spec(self, spec, spec_set, _spec_as_instance=False,
_eat_self=False):
u"""添加spec mock方法."""
_spec_class = None
_spec_signature = None
if spec is not None and not _is_list(spec):
if isinstance(spec, ClassTypes):
_spec_class = spec
else:
_spec_class = _get_class(spec)
# spec类的签名
res = _get_signature_object(spec,
_spec_as_instance, _eat_self)
_spec_signature = res and res[1]
spec = dir(spec)
__dict__ = self.__dict__
__dict__['_spec_class'] = _spec_class
__dict__['_spec_set'] = spec_set
__dict__['_spec_signature'] = _spec_signature
__dict__['_mock_methods'] = spec
def __get_return_value(self):
ret = self._mock_return_value
if self._mock_delegate is not None:
ret = self._mock_delegate.return_value
if ret is DEFAULT:
ret = self._get_child_mock(
_new_parent=self, _new_name='()'
)
self.return_value = ret
return ret
def __set_return_value(self, value):
if self._mock_delegate is not None:
self._mock_delegate.return_value = value
else:
self._mock_return_value = value
_check_and_set_parent(self, value, None, '()')
__return_value_doc = "The value to be returned when the mock is called."
return_value = property(__get_return_value, __set_return_value,
__return_value_doc)
@property
def __class__(self):
if self._spec_class is None:
return type(self)
return self._spec_class
called = _delegating_property('called')
call_count = _delegating_property('call_count')
call_args = _delegating_property('call_args')
call_args_list = _delegating_property('call_args_list')
mock_calls = _delegating_property('mock_calls')
def __get_side_effect(self):
delegated = self._mock_delegate
if delegated is None:
return self._mock_side_effect
sf = delegated.side_effect
if (sf is not None and not callable(sf)
and not isinstance(sf, _MockIter) and not _is_exception(sf)):
sf = _MockIter(sf)
delegated.side_effect = sf
return sf
def __set_side_effect(self, value):
value = _try_iter(value)
delegated = self._mock_delegate
if delegated is None:
self._mock_side_effect = value
else:
delegated.side_effect = value
side_effect = property(__get_side_effect, __set_side_effect)
def reset_mock(self, visited=None):
"Restore the mock object to its initial state."
if visited is None:
visited = []
if id(self) in visited:
return
visited.append(id(self))
self.called = False
self.call_args = None
self.call_count = 0
self.mock_calls = _CallList()
self.call_args_list = _CallList()
self.method_calls = _CallList()
for child in self._mock_children.values():
if isinstance(child, _SpecState):
continue
child.reset_mock(visited)
ret = self._mock_return_value
if _is_instance_mock(ret) and ret is not self:
ret.reset_mock(visited)
def configure_mock(self, **kwargs):
"""Set attributes on the mock through keyword arguments.
Attributes plus return values and side effects can be set on child
mocks using standard dot notation and unpacking a dictionary in the
method call:
>>> attrs = {'method.return_value': 3, 'other.side_effect': KeyError}
>>> mock.configure_mock(**attrs)"""
for arg, val in sorted(kwargs.items(),
# we sort on the number of dots so that
# attributes are set before we set attributes on
# attributes
key=lambda entry: entry[0].count('.')):
args = arg.split('.')
final = args.pop()
obj = self
for entry in args:
obj = getattr(obj, entry)
setattr(obj, final, val)
def __getattr__(self, name):
u"""获取mock对象属性，不存在的创建mock对象"""
if name in ('_mock_methods', '_mock_unsafe'):
raise AttributeError(name)
elif self._mock_methods is not None:
if name not in self._mock_methods or name in _all_magics:
raise AttributeError("Mock object has no attribute %r" % name)
elif _is_magic(name):
raise AttributeError(name)
if not self._mock_unsafe:
if name.startswith(('assert', 'assret')):
raise AttributeError(name)
result = self._mock_children.get(name)
if result is _deleted:
raise AttributeError(name)
elif result is None:
wraps = None
if self._mock_wraps is not None:
# XXXX should we get the attribute without triggering code
# execution?
wraps = getattr(self._mock_wraps, name)
result = self._get_child_mock(
parent=self, name=name, wraps=wraps, _new_name=name,
_new_parent=self
)
self._mock_children[name] = result
elif isinstance(result, _SpecState):
result = create_autospec(
result.spec, result.spec_set, result.instance,
result.parent, result.name
)
self._mock_children[name] = result
return result
def __repr__(self):
_name_list = [self._mock_new_name]
_parent = self._mock_new_parent
last = self
dot = '.'
if _name_list == ['()']:
dot = ''
seen = set()
while _parent is not None:
last = _parent
_name_list.append(_parent._mock_new_name + dot)
dot = '.'
if _parent._mock_new_name == '()':
dot = ''
_parent = _parent._mock_new_parent
# use ids here so as not to call __hash__ on the mocks
if id(_parent) in seen:
break
seen.add(id(_parent))
_name_list = list(reversed(_name_list))
_first = last._mock_name or 'mock'
if len(_name_list) > 1:
if _name_list[1] not in ('()', '().'):
_first += '.'
_name_list[0] = _first
name = ''.join(_name_list)
name_string = ''
if name not in ('mock', 'mock.'):
name_string = ' name=%r' % name
spec_string = ''
if self._spec_class is not None:
spec_string = ' spec=%r'
if self._spec_set:
spec_string = ' spec_set=%r'
spec_string = spec_string % self._spec_class.__name__
return "<%s%s%s id='%s'>" % (
type(self).__name__,
name_string,
spec_string,
id(self)
)
def __dir__(self):
"""Filter the output of `dir(mock)` to only useful members."""
if not mock.FILTER_DIR and getattr(object, '__dir__', None):
# object.__dir__ is not in 2.7
return object.__dir__(self)
extras = self._mock_methods or []
from_type = dir(type(self))
from_dict = list(self.__dict__)
if mock.FILTER_DIR:
# object.__dir__ is not in 2.7
from_type = [e for e in from_type if not e.startswith('_')]
from_dict = [e for e in from_dict if not e.startswith('_') or
_is_magic(e)]
return sorted(set(extras + from_type + from_dict +
list(self._mock_children)))
def __setattr__(self, name, value):
u"""设置mock对象属性，如果传递spec_set会进行检查"""
if name in _allowed_names:
# property setters go through here
return object.__setattr__(self, name, value)
elif (self._spec_set and self._mock_methods is not None and
#设置spec_set为True不能设置不存在的属性
name not in self._mock_methods and
name not in self.__dict__):
# 不能设置非mock方法和不存在属性
raise AttributeError("Mock object has no attribute '%s'" % name)
elif name in _unsupported_magics:
msg = 'Attempting to set unsupported magic method %r.' % name
raise AttributeError(msg)
elif name in _all_magics:
if self._mock_methods is not None and name not in self._mock_methods:
raise AttributeError("Mock object has no attribute '%s'" % name)
if not _is_instance_mock(value):
setattr(type(self), name, _get_method(name, value))
original = value
value = lambda *args, **kw: original(self, *args, **kw)
else:
# only set _new_name and not name so that mock_calls is tracked
# but not method calls
_check_and_set_parent(self, value, None, name)
setattr(type(self), name, value)
self._mock_children[name] = value
elif name == '__class__':
self._spec_class = value
return
else:
if _check_and_set_parent(self, value, name, name):
self._mock_children[name] = value
return object.__setattr__(self, name, value)
def __delattr__(self, name):
if name in _all_magics and name in type(self).__dict__:
delattr(type(self), name)
if name not in self.__dict__:
# for magic methods that are still MagicProxy objects and
# not set on the instance itself
return
if name in self.__dict__:
object.__delattr__(self, name)
obj = self._mock_children.get(name, _missing)
if obj is _deleted:
raise AttributeError(name)
if obj is not _missing:
del self._mock_children[name]
self._mock_children[name] = _deleted
def _format_mock_call_signature(self, args, kwargs):
name = self._mock_name or 'mock'
return _format_call_signature(name, args, kwargs)
def _format_mock_failure_message(self, args, kwargs):
message = 'Expected call: %s\nActual call: %s'
expected_string = self._format_mock_call_signature(args, kwargs)
call_args = self.call_args
if len(call_args) == 3:
call_args = call_args[1:]
actual_string = self._format_mock_call_signature(*call_args)
return message % (expected_string, actual_string)
def _call_matcher(self, _call):
"""
Given a call (or simply a (args, kwargs) tuple), return a
comparison key suitable for matching with other calls.
This is a best effort method which relies on the spec's signature,
if available, or falls back on the arguments themselves.
"""
sig = self._spec_signature
if sig is not None:
if len(_call) == 2:
name = ''
args, kwargs = _call
else:
name, args, kwargs = _call
try:
return name, sig.bind(*args, **kwargs)
except TypeError as e:
e.__traceback__ = None
return e
else:
return _call
def assert_not_called(_mock_self):
"""assert that the mock was never called.
"""
self = _mock_self
if self.call_count != 0:
msg = ("Expected '%s' to not have been called. Called %s times." %
(self._mock_name or 'mock', self.call_count))
raise AssertionError(msg)
def assert_called(_mock_self):
"""assert that the mock was called at least once
"""
self = _mock_self
if self.call_count == 0:
msg = ("Expected '%s' to have been called." %
self._mock_name or 'mock')
raise AssertionError(msg)
def assert_called_once(_mock_self):
"""assert that the mock was called only once.
"""
self = _mock_self
if not self.call_count == 1:
msg = ("Expected '%s' to have been called once. Called %s times." %
(self._mock_name or 'mock', self.call_count))
raise AssertionError(msg)
def assert_called_with(_mock_self, *args, **kwargs):
"""assert that the mock was called with the specified arguments.
Raises an AssertionError if the args and keyword args passed in are
different to the last call to the mock."""
self = _mock_self
if self.call_args is None:
expected = self._format_mock_call_signature(args, kwargs)
raise AssertionError('Expected call: %s\nNot called' % (expected,))
def _error_message(cause):
msg = self._format_mock_failure_message(args, kwargs)
if six.PY2 and cause is not None:
# Tack on some diagnostics for Python without __cause__
msg = '%s\n%s' % (msg, str(cause))
return msg
expected = self._call_matcher((args, kwargs))
actual = self._call_matcher(self.call_args)
if expected != actual:
cause = expected if isinstance(expected, Exception) else None
six.raise_from(AssertionError(_error_message(cause)), cause)
def assert_called_once_with(_mock_self, *args, **kwargs):
"""assert that the mock was called exactly once and with the specified
arguments."""
self = _mock_self
if not self.call_count == 1:
msg = ("Expected '%s' to be called once. Called %s times." %
(self._mock_name or 'mock', self.call_count))
raise AssertionError(msg)
return self.assert_called_with(*args, **kwargs)
def assert_has_calls(self, calls, any_order=False):
"""assert the mock has been called with the specified calls.
The `mock_calls` list is checked for the calls.
If `any_order` is False (the default) then the calls must be
sequential. There can be extra calls before or after the
specified calls.
If `any_order` is True then the calls can be in any order, but
they must all appear in `mock_calls`."""
expected = [self._call_matcher(c) for c in calls]
cause = expected if isinstance(expected, Exception) else None
all_calls = _CallList(self._call_matcher(c) for c in self.mock_calls)
if not any_order:
if expected not in all_calls:
six.raise_from(AssertionError(
'Calls not found.\nExpected: %r\n'
'Actual: %r' % (_CallList(calls), self.mock_calls)
), cause)
return
all_calls = list(all_calls)
not_found = []
for kall in expected:
try:
all_calls.remove(kall)
except ValueError:
not_found.append(kall)
if not_found:
six.raise_from(AssertionError(
'%r not all found in call list' % (tuple(not_found),)
), cause)
def assert_any_call(self, *args, **kwargs):
"""assert the mock has been called with the specified arguments.
The assert passes if the mock has *ever* been called, unlike
`assert_called_with` and `assert_called_once_with` that only pass if
the call is the most recent one."""
expected = self._call_matcher((args, kwargs))
actual = [self._call_matcher(c) for c in self.call_args_list]
if expected not in actual:
cause = expected if isinstance(expected, Exception) else None
expected_string = self._format_mock_call_signature(args, kwargs)
six.raise_from(AssertionError(
'%s call not found' % expected_string
), cause)
def _get_child_mock(self, **kw):
"""Create the child mocks for attributes and return value.
By default child mocks will be the same type as the parent.
Subclasses of Mock may want to override this to customize the way
child mocks are made.
For non-callable mocks the callable variant will be used (rather than
any custom subclass)."""
_type = type(self)
if not issubclass(_type, CallableMixin):
if issubclass(_type, NonCallableMagicMock):
klass = MagicMock
elif issubclass(_type, NonCallableMock) :
klass = Mock
else:
klass = _type.__mro__[1]
return klass(**kw)
def _try_iter(obj):
if obj is None:
return obj
if _is_exception(obj):
return obj
if _callable(obj):
return obj
try:
return iter(obj)
except TypeError:
# XXXX backwards compatibility
# but this will blow up on first call - so maybe we should fail early?
return obj
class CallableMixin(Base):
u"""可以调用的mock类.
负责调用逻辑封装，添加签名检查
负责调用统计工作
"""
def __init__(self, spec=None, side_effect=None, return_value=DEFAULT,
wraps=None, name=None, spec_set=None, parent=None,
_spec_state=None, _new_name='', _new_parent=None, **kwargs):
self.__dict__['_mock_return_value'] = return_value
_safe_super(CallableMixin, self).__init__(
spec, wraps, name, spec_set, parent,
_spec_state, _new_name, _new_parent, **kwargs
)
self.side_effect = side_effect
def _mock_check_sig(self, *args, **kwargs):
# stub method that can be replaced with one with a specific signature
pass
def __call__(_mock_self, *args, **kwargs):
# can't use self in-case a function / method we are mocking uses self
# in the signature
# 函数签名检查
_mock_self._mock_check_sig(*args, **kwargs)
return _mock_self._mock_call(*args, **kwargs)
def _mock_call(_mock_self, *args, **kwargs):
# mock调用统计
self = _mock_self
self.called = True
self.call_count += 1
_new_name = self._mock_new_name
_new_parent = self._mock_new_parent
_call = _Call((args, kwargs), two=True)
self.call_args = _call
self.call_args_list.append(_call)
self.mock_calls.append(_Call(('', args, kwargs)))
seen = set()
skip_next_dot = _new_name == '()'
do_method_calls = self._mock_parent is not None
name = self._mock_name
while _new_parent is not None:
this_mock_call = _Call((_new_name, args, kwargs))
if _new_parent._mock_new_name:
dot = '.'
if skip_next_dot:
dot = ''
skip_next_dot = False
if _new_parent._mock_new_name == '()':
skip_next_dot = True
_new_name = _new_parent._mock_new_name + dot + _new_name
if do_method_calls:
if _new_name == name:
this_method_call = this_mock_call
else:
this_method_call = _Call((name, args, kwargs))
_new_parent.method_calls.append(this_method_call)
do_method_calls = _new_parent._mock_parent is not None
if do_method_calls:
name = _new_parent._mock_name + '.' + name
_new_parent.mock_calls.append(this_mock_call)
_new_parent = _new_parent._mock_new_parent
# use ids here so as not to call __hash__ on the mocks
_new_parent_id = id(_new_parent)
if _new_parent_id in seen:
break
seen.add(_new_parent_id)
# 返回值默认是DEFAULT
ret_val = DEFAULT
effect = self.side_effect
if effect is not None:
# side_effect抛出异常
if _is_exception(effect):
raise effect
if not _callable(effect):
# 如果side_effect是列表则依次取列表值
result = next(effect)
if _is_exception(result):
raise result
if result is DEFAULT:
result = self.return_value
return result
# 如果side_effect可调用则调用取返回值
ret_val = effect(*args, **kwargs)
if (self._mock_wraps is not None and
self._mock_return_value is DEFAULT):
return self._mock_wraps(*args, **kwargs)
if ret_val is DEFAULT:
# 如果side_effect返回值为DEFAULT则返回return_value
ret_val = self.return_value
return ret_val
class Mock(CallableMixin, NonCallableMock):
"""
Create a new `Mock` object. `Mock` takes several optional arguments
that specify the behaviour of the Mock object:
* `spec`: This can be either a list of strings or an existing object (a
class or instance) that acts as the specification for the mock object. If
you pass in an object then a list of strings is formed by calling dir on
the object (excluding unsupported magic attributes and methods). Accessing
any attribute not in this list will raise an `AttributeError`.
If `spec` is an object (rather than a list of strings) then
`mock.__class__` returns the class of the spec object. This allows mocks
to pass `isinstance` tests.
* `spec_set`: A stricter variant of `spec`. If used, attempting to *set*
or get an attribute on the mock that isn't on the object passed as
`spec_set` will raise an `AttributeError`.
* `side_effect`: A function to be called whenever the Mock is called. See
the `side_effect` attribute. Useful for raising exceptions or
dynamically changing return values. The function is called with the same
arguments as the mock, and unless it returns `DEFAULT`, the return
value of this function is used as the return value.
Alternatively `side_effect` can be an exception class or instance. In
this case the exception will be raised when the mock is called.
If `side_effect` is an iterable then each call to the mock will return
the next value from the iterable. If any of the members of the iterable
are exceptions they will be raised instead of returned.
* `return_value`: The value returned when the mock is called. By default
this is a new Mock (created on first access). See the
`return_value` attribute.
* `wraps`: Item for the mock object to wrap. If `wraps` is not None then
calling the Mock will pass the call through to the wrapped object
(returning the real result). Attribute access on the mock will return a
Mock object that wraps the corresponding attribute of the wrapped object
(so attempting to access an attribute that doesn't exist will raise an
`AttributeError`).
If the mock has an explicit `return_value` set then calls are not passed
to the wrapped object and the `return_value` is returned instead.
* `name`: If the mock has a name then it will be used in the repr of the
mock. This can be useful for debugging. The name is propagated to child
mocks.
Mocks can also be called with arbitrary keyword arguments. These will be
used to set attributes on the mock after it is created.
"""
def _dot_lookup(thing, comp, import_path):
try:
return getattr(thing, comp)
except AttributeError:
# 对于phoenix.server.manager情况必须先import phoenix.server.manager
# 才能从phoenix.server模块中获取manager属性，否则会抛属性不存在异常
__import__(import_path)
return getattr(thing, comp)
def _importer(target):
"""执行实际导入工作的函数体"""
components = target.split('.')
import_path = components.pop(0)
thing = __import__(import_path)
for comp in components:
# 不能直接import，需采用层层递进的方式导入宿主对象
import_path += ".%s" % comp
thing = _dot_lookup(thing, comp, import_path)
return thing
def _is_started(patcher):
# XXXX horrible
return hasattr(patcher, 'is_local')
class _patch(object):
"""补丁对象"""
attribute_name = None
_active_patches = []
def __init__(
self, getter, attribute, new, spec, create,
spec_set, autospec, new_callable, kwargs
):
if new_callable is not None:
if new is not DEFAULT:
# 不能同时指定new和new_callable
raise ValueError(
"Cannot use 'new' and 'new_callable' together"
)
if autospec is not None:
# 不能同时指定autospec和new_callable
raise ValueError(
"Cannot use 'autospec' and 'new_callable' together"
)
self.getter = getter
self.attribute = attribute
self.new = new
self.new_callable = new_callable
self.spec = spec
self.create = create
self.has_local = False
self.spec_set = spec_set
self.autospec = autospec
self.kwargs = kwargs
self.additional_patchers = []
def copy(self):
patcher = _patch(
self.getter, self.attribute, self.new, self.spec,
self.create, self.spec_set,
self.autospec, self.new_callable, self.kwargs
)
patcher.attribute_name = self.attribute_name
patcher.additional_patchers = [
p.copy() for p in self.additional_patchers
]
return patcher
def __call__(self, func):
# __call__后于__init__后调用
if isinstance(func, ClassTypes):
# 装饰类
return self.decorate_class(func)
# 装饰方法
return self.decorate_callable(func)
def decorate_class(self, klass):
u"""装饰整个单元测试类."""
for attr in dir(klass):
if not attr.startswith(patch.TEST_PREFIX):
# 跳过非_test开头的方法
continue
attr_value = getattr(klass, attr)
if not hasattr(attr_value, "__call__"):
# 跳过非调用属性
continue
patcher = self.copy()
# 依次每个测试用例方法调用__call__
setattr(klass, attr, patcher(attr_value))
return klass
def decorate_callable(self, func):
u"""装饰单个单元测试方法.
Args:
func:被装饰的方法
"""
if hasattr(func, 'patchings'):
# python装饰器从下往上解析，就近原则
# 当有多个装饰器作用时都添加的方法的patchings属性中
func.patchings.append(self)
return func
# wraps装饰器的作用时保存原方法的元信息
@wraps(func)
def patched(*args, **keywargs):
u"""被打补丁后的方法."""
# 补丁对象参数集合
extra_args = []
#已打好补丁集合
entered_patchers = []
exc_info = tuple()
try:
# 依次打补丁
for patching in patched.patchings:
# 打补丁，并返回补丁对象
arg = patching.__enter__()
# 将已经打好的补丁添加到已打补丁集合中
entered_patchers.append(patching)
if patching.attribute_name is not None:
keywargs.update(arg)
elif patching.new is DEFAULT:
# 没有指定补丁对象，就将当前已打好的补丁对象添加到参数
# 集合中，并传递给所装饰的方法
extra_args.append(arg)
# 将打好的补丁对象集合传递给方法
args += tuple(extra_args)
return func(*args, **keywargs)
except:
if (patching not in entered_patchers and
_is_started(patching)):
# 确保所有已打的补丁都会被解除，不残留
# the patcher may have been started, but an exception
# raised whilst entering one of its additional_patchers
entered_patchers.append(patching)
# Pass the exception to __exit__
exc_info = sys.exc_info()
# re-raise the exception
raise
finally:
# 反向依次解除所有补丁，跟打补丁的顺序相反
for patching in reversed(entered_patchers):
# 解除补丁
patching.__exit__(*exc_info)
# 打第一个补丁创建patchings属性
patched.patchings = [self]
return patched
def get_original(self):
u"""获取打补丁前原始的对象."""
# 导入宿主对象
target = self.getter()
# 将被打补丁对象在宿主对象中的属性名称
name = self.attribute
original = DEFAULT
# 补丁对象是否在本地查找空间中
local = False
try:
# 从宿主对象中获取要打补丁的原始对象
original = target.__dict__[name]
except (AttributeError, KeyError):
original = getattr(target, name, DEFAULT)
else:
# 在本地查找空间中
local = True
if name in _builtins and isinstance(target, ModuleType):
# 要打补丁的对象在__builtin__内置模块中
self.create = True
if not self.create and original is DEFAULT:
# 即不在__builtin__模块中也不在本地中，属性不存在
raise AttributeError(
"%s does not have the attribute %r" % (target, name)
)
return original, local
def __enter__(self):
u"""Perform the patch.
打补丁的真正方法执行过程.
"""
new, spec, spec_set = self.new, self.spec, self.spec_set
autospec, kwargs = self.autospec, self.kwargs
new_callable = self.new_callable
# 当方法实际执行的时候才正式导入宿主对象
self.target = self.getter()
# normalise False to None
if spec is False:
spec = None
if spec_set is False:
spec_set = None
if autospec is False:
autospec = None
if spec is not None and autospec is not None:
# spec和autospec参数不能同时指定
raise TypeError("Can't specify spec and autospec")
if ((spec is not None or autospec is not None) and
spec_set not in (True, None)):
# 当指定spec或autospec参数时，spec_set参数只能指定True值或不指定值
raise TypeError("Can't provide explicit spec_set *and* spec or autospec")
# 获取打补丁前原始的对象
original, local = self.get_original()
if new is DEFAULT and autospec is None:
inherit = False
# spec和spec_set参数处理细节
if spec is True:
# set spec to the object we are replacing
spec = original
if spec_set is True:
spec_set = original
spec = None
elif spec is not None:
if spec_set is True:
spec_set = spec
spec = None
elif spec_set is True:
spec_set = original
if spec is not None or spec_set is not None:
if original is DEFAULT:
# __builtin__模块不支持spec、spec_set
raise TypeError("Can't use 'spec' with create=True")
if isinstance(original, ClassTypes):
# If we're patching out a class and there is a spec
# 如果是类，子类要打补丁
inherit = True
# 默认补丁对象类型是MagicMock
Klass = MagicMock
_kwargs = {}
if new_callable is not None:
# new_callable传递的情况，补丁对象就是new_callable返回值
Klass = new_callable
elif spec is not None or spec_set is not None:
this_spec = spec
if spec_set is not None:
this_spec = spec_set
if _is_list(this_spec):
not_callable = '__call__' not in this_spec
else:
not_callable = not _callable(this_spec)
if not_callable:
# spec规定补丁对象不能被调用
Klass = NonCallableMagicMock
# 将spec、spec_set参数传递给补丁对象
if spec is not None:
_kwargs['spec'] = spec
if spec_set is not None:
_kwargs['spec_set'] = spec_set
# add a name to mocks
if (isinstance(Klass, type) and
issubclass(Klass, NonCallableMock) and self.attribute):
_kwargs['name'] = self.attribute
_kwargs.update(kwargs)
new = Klass(**_kwargs)
if inherit and _is_instance_mock(new):
# we can only tell if the instance should be callable if the
# spec is not a list
this_spec = spec
if spec_set is not None:
this_spec = spec_set
if (not _is_list(this_spec) and not
_instance_callable(this_spec)):
Klass = NonCallableMagicMock
_kwargs.pop('name')
new.return_value = Klass(_new_parent=new, _new_name='()',
**_kwargs)
elif autospec is not None:
# autospec传递情况下会根据原始对象生成mock对象
# spec被忽略，new必须是DEFAULT，spec_set被作为bool值处理
# spec is ignored, new *must* be default, spec_set is treated
# as a boolean. Should we check spec is not None and that spec_set
# is a bool?
if new is not DEFAULT:
# 指定autospec时不能指定new
raise TypeError(
"autospec creates the mock for you. Can't specify "
"autospec and new."
)
if original is DEFAULT:
#__builtins__不支持autospec
raise TypeError("Can't use 'autospec' with create=True")
# 将spec_set转为bool类型
spec_set = bool(spec_set)
if autospec is True:
autospec = original
new = create_autospec(autospec, spec_set=spec_set,
_name=self.attribute, **kwargs)
elif kwargs:
# can't set keyword args when we aren't creating the mock
# XXXX If new is a Mock we could call new.configure_mock(**kwargs)
raise TypeError("Can't pass kwargs to a mock we aren't creating")
new_attr = new
self.temp_original = original
self.is_local = local
# 替换原先对象
setattr(self.target, self.attribute, new_attr)
if self.attribute_name is not None:
extra_args = {}
if self.new is DEFAULT:
extra_args[self.attribute_name] = new
for patching in self.additional_patchers:
arg = patching.__enter__()
if patching.new is DEFAULT:
extra_args.update(arg)
return extra_args
return new
def __exit__(self, *exc_info):
"""Undo the patch."""
if not _is_started(self):
raise RuntimeError('stop called on unstarted patcher')
if self.is_local and self.temp_original is not DEFAULT:
setattr(self.target, self.attribute, self.temp_original)
else:
delattr(self.target, self.attribute)
if not self.create and (not hasattr(self.target, self.attribute) or
self.attribute in ('__doc__', '__module__',
'__defaults__', '__annotations__',
'__kwdefaults__')):
# needed for proxy objects like django settings
setattr(self.target, self.attribute, self.temp_original)
del self.temp_original
del self.is_local
del self.target
for patcher in reversed(self.additional_patchers):
if _is_started(patcher):
patcher.__exit__(*exc_info)
def start(self):
"""Activate a patch, returning any created mock."""
result = self.__enter__()
self._active_patches.append(self)
return result
def stop(self):
"""Stop an active patch."""
try:
self._active_patches.remove(self)
except ValueError:
# If the patch hasn't been started this will fail
pass
return self.__exit__()
def _get_target(target):
"""
返回导入宿主对象的函数和被mock对象在宿主对象中属性名称
"""
try:
# 如果target=phoenix.server.manager.Manager
# 那么拆分后target=phoenix.server.manager，attribute=Manager
target, attribute = target.rsplit('.', 1)
except (TypeError, ValueError):
# 像target=os情况会抛出异常
raise TypeError("Need a valid target to patch. You supplied: %r" %
(target,))
# getter是python语法糖lambda生成的一个匿名函数
# 函数体就是 _importer(target)
getter = lambda: _importer(target)
return getter, attribute
def _patch_object(
target, attribute, new=DEFAULT, spec=None,
create=False, spec_set=None, autospec=None,
new_callable=None, **kwargs
):
"""给对象的attribute打补丁"""
"""
patch the named member (`attribute`) on an object (`target`) with a mock
object.
`patch.object` can be used as a decorator, class decorator or a context
manager. Arguments `new`, `spec`, `create`, `spec_set`,
`autospec` and `new_callable` have the same meaning as for `patch`. Like
`patch`, `patch.object` takes arbitrary keyword arguments for configuring
the mock object it creates.
When used as a class decorator `patch.object` honours `patch.TEST_PREFIX`
for choosing which methods to wrap.
"""
getter = lambda: target
return _patch(
getter, attribute, new, spec, create,
spec_set, autospec, new_callable, kwargs
)
def _patch_multiple(target, spec=None, create=False, spec_set=None,
autospec=None, new_callable=None, **kwargs):
u"""一条patch代码打多个补丁"""
"""Perform multiple patches in a single call. It takes the object to be
patched (either as an object or a string to fetch the object by importing)
and keyword arguments for the patches::
with patch.multiple(settings, FIRST_PATCH='one', SECOND_PATCH='two'):
...
Use `DEFAULT` as the value if you want `patch.multiple` to create
mocks for you. In this case the created mocks are passed into a decorated
function by keyword, and a dictionary is returned when `patch.multiple` is
used as a context manager.
`patch.multiple` can be used as a decorator, class decorator or a context
manager. The arguments `spec`, `spec_set`, `create`,
`autospec` and `new_callable` have the same meaning as for `patch`. These
arguments will be applied to *all* patches done by `patch.multiple`.
When used as a class decorator `patch.multiple` honours `patch.TEST_PREFIX`
for choosing which methods to wrap.
"""
if type(target) in (unicode, str):
getter = lambda: _importer(target)
else:
getter = lambda: target
if not kwargs:
raise ValueError(
'Must supply at least one keyword argument with patch.multiple'
)
# need to wrap in a list for python 3, where items is a view
items = list(kwargs.items())
attribute, new = items[0]
patcher = _patch(
getter, attribute, new, spec, create, spec_set,
autospec, new_callable, {}
)
patcher.attribute_name = attribute
for attribute, new in items[1:]:
this_patcher = _patch(
getter, attribute, new, spec, create, spec_set,
autospec, new_callable, {}
)
this_patcher.attribute_name = attribute
patcher.additional_patchers.append(this_patcher)
return patcher
def patch(
target, new=DEFAULT, spec=None, create=False,
spec_set=None, autospec=None, new_callable=None, **kwargs
):
"""
patch是单元测试用例中使用广泛的装饰器.
mock.patch即可用在测试用例方法上，也可以用在测试类上。可以看到patch接收多个
参数，分别是target、new、spec、create、spec_set、autospec、new_callable、
kwargs，下面解释下各个参数的作用：
target：可导入，需要替换的对象
new：如果忽略new参数，那么target就会被MagicMock对象替换，否则被new对象替换。
spec：可以是list、类、True，如果是list则新生成的mock对象只包含list中的属性
和方法，如果是类，则只包含类中的属性和方法，如果是True则包含原始对象中所有
的属性和方法。
spec_set：能传True或类，表示设置存在的属性。
create：指定为True，当要替换的属性不存在的时候，就创建该属性，危险！
autospec：指定为True，只包含原对象中的方法和属性，并会进行方法调用参数强校验
new_callable：可以指定其他类或可调用对象替换掉默认的MagicMock对象
kwargs：可以传递给MagicMock初始化方法或被装饰的方法
`patch` acts as a function decorator, class decorator or a context
manager. Inside the body of the function or with statement, the `target`
is patched with a `new` object. When the function/with statement exits
the patch is undone.
If `new` is omitted, then the target is replaced with a
`MagicMock`. If `patch` is used as a decorator and `new` is
omitted, the created mock is passed in as an extra argument to the
decorated function. If `patch` is used as a context manager the created
mock is returned by the context manager.
`target` should be a string in the form `'package.module.ClassName'`. The
`target` is imported and the specified object replaced with the `new`
object, so the `target` must be importable from the environment you are
calling `patch` from. The target is imported when the decorated function
is executed, not at decoration time.
The `spec` and `spec_set` keyword arguments are passed to the `MagicMock`
if patch is creating one for you.
In addition you can pass `spec=True` or `spec_set=True`, which causes
patch to pass in the object being mocked as the spec/spec_set object.
`new_callable` allows you to specify a different class, or callable object,
that will be called to create the `new` object. By default `MagicMock` is
used.
A more powerful form of `spec` is `autospec`. If you set `autospec=True`
then the mock will be created with a spec from the object being replaced.
All attributes of the mock will also have the spec of the corresponding
attribute of the object being replaced. Methods and functions being
mocked will have their arguments checked and will raise a `TypeError` if
they are called with the wrong signature. For mocks replacing a class,
their return value (the 'instance') will have the same spec as the class.
Instead of `autospec=True` you can pass `autospec=some_object` to use an
arbitrary object as the spec instead of the one being replaced.
By default `patch` will fail to replace attributes that don't exist. If
you pass in `create=True`, and the attribute doesn't exist, patch will
create the attribute for you when the patched function is called, and
delete it again afterwards. This is useful for writing tests against
attributes that your production code creates at runtime. It is off by
default because it can be dangerous. With it switched on you can write
passing tests against APIs that don't actually exist!
Patch can be used as a `TestCase` class decorator. It works by
decorating each test method in the class. This reduces the boilerplate
code when your test methods share a common patchings set. `patch` finds
tests by looking for method names that start with `patch.TEST_PREFIX`.
By default this is `test`, which matches the way `unittest` finds tests.
You can specify an alternative prefix by setting `patch.TEST_PREFIX`.
Patch can be used as a context manager, with the with statement. Here the
patching applies to the indented block after the with statement. If you
use "as" then the patched object will be bound to the name after the
"as"; very useful if `patch` is creating a mock object for you.
`patch` takes arbitrary keyword arguments. These will be passed to
the `Mock` (or `new_callable`) on construction.
`patch.dict(...)`, `patch.multiple(...)` and `patch.object(...)` are
available for alternate use-cases.
"""
# 获取被mock对象的宿主对象，和被mock对象在宿主对象中的属性名称
# 注意这里的getter并不是对象，而是可以导入对象的一个函数，只有当被装饰方法
# 实际调用的时候才真正导入宿主对象
getter, attribute = _get_target(target)
return _patch(
getter, attribute, new, spec, create,
spec_set, autospec, new_callable, kwargs
)
class _patch_dict(object):
"""给dict或对象打补丁"""
"""
Patch a dictionary, or dictionary like object, and restore the dictionary
to its original state after the test.
`in_dict` can be a dictionary or a mapping like container. If it is a
mapping then it must at least support getting, setting and deleting items
plus iterating over keys.
`in_dict` can also be a string specifying the name of the dictionary, which
will then be fetched by importing it.
`values` can be a dictionary of values to set in the dictionary. `values`
can also be an iterable of `(key, value)` pairs.
If `clear` is True then the dictionary will be cleared before the new
values are set.
`patch.dict` can also be called with arbitrary keyword arguments to set
values in the dictionary::
with patch.dict('sys.modules', mymodule=Mock(), other_module=Mock()):
...
`patch.dict` can be used as a context manager, decorator or class
decorator. When used as a class decorator `patch.dict` honours
`patch.TEST_PREFIX` for choosing which methods to wrap.
"""
def __init__(self, in_dict, values=(), clear=False, **kwargs):
if isinstance(in_dict, basestring):
in_dict = _importer(in_dict)
self.in_dict = in_dict
# support any argument supported by dict(...) constructor
self.values = dict(values)
self.values.update(kwargs)
self.clear = clear
self._original = None
def __call__(self, f):
if isinstance(f, ClassTypes):
return self.decorate_class(f)
@wraps(f)
def _inner(*args, **kw):
self._patch_dict()
try:
return f(*args, **kw)
finally:
self._unpatch_dict()
return _inner
def decorate_class(self, klass):
for attr in dir(klass):
attr_value = getattr(klass, attr)
if (attr.startswith(patch.TEST_PREFIX) and
hasattr(attr_value, "__call__")):
decorator = _patch_dict(self.in_dict, self.values, self.clear)
decorated = decorator(attr_value)
setattr(klass, attr, decorated)
return klass
def __enter__(self):
"""Patch the dict."""
self._patch_dict()
def _patch_dict(self):
values = self.values
in_dict = self.in_dict
clear = self.clear
try:
original = in_dict.copy()
except AttributeError:
# dict like object with no copy method
# must support iteration over keys
original = {}
for key in in_dict:
original[key] = in_dict[key]
# 把原始的先保存起来
self._original = original
if clear:
_clear_dict(in_dict)
try:
in_dict.update(values)
except AttributeError:
# dict like object with no update method
for key in values:
in_dict[key] = values[key]
def _unpatch_dict(self):
in_dict = self.in_dict
original = self._original
_clear_dict(in_dict)
try:
# 恢复原始值
in_dict.update(original)
except AttributeError:
for key in original:
in_dict[key] = original[key]
def __exit__(self, *args):
"""Unpatch the dict."""
self._unpatch_dict()
return False
start = __enter__
stop = __exit__
def _clear_dict(in_dict):
try:
in_dict.clear()
except AttributeError:
keys = list(in_dict)
for key in keys:
del in_dict[key]
def _patch_stopall():
"""取消所有补丁"""
"""Stop all active patches. LIFO to unroll nested patches."""
for patch in reversed(_patch._active_patches):
patch.stop()
patch.object = _patch_object
patch.dict = _patch_dict
patch.multiple = _patch_multiple
patch.stopall = _patch_stopall
patch.TEST_PREFIX = 'test'
magic_methods = (
"lt le gt ge eq ne "
"getitem setitem delitem "
"len contains iter "
"hash str sizeof "
"enter exit "
# we added divmod and rdivmod here instead of numerics
# because there is no idivmod
"divmod rdivmod neg pos abs invert "
"complex int float index "
"trunc floor ceil "
)
numerics = (
"add sub mul matmul div floordiv mod lshift rshift and xor or pow"
)
if six.PY3:
numerics += ' truediv'
inplace = ' '.join('i%s' % n for n in numerics.split())
right = ' '.join('r%s' % n for n in numerics.split())
extra = ''
if six.PY3:
extra = 'bool next '
else:
extra = 'unicode long nonzero oct hex truediv rtruediv '
# not including __prepare__, __instancecheck__, __subclasscheck__
# (as they are metaclass methods)
# __del__ is not supported at all as it causes problems if it exists
_non_defaults = set((
'__cmp__', '__getslice__', '__setslice__', '__coerce__', # <3.x
'__get__', '__set__', '__delete__', '__reversed__', '__missing__',
'__reduce__', '__reduce_ex__', '__getinitargs__', '__getnewargs__',
'__getstate__', '__setstate__', '__getformat__', '__setformat__',
'__repr__', '__dir__', '__subclasses__', '__format__',
))
def _get_method(name, func):
"Turns a callable object (like a mock) into a real function"
def method(self, *args, **kw):
return func(self, *args, **kw)
method.__name__ = name
return method
_magics = set(
'__%s__' % method for method in
' '.join([magic_methods, numerics, inplace, right, extra]).split()
)
_all_magics = _magics | _non_defaults
_unsupported_magics = set((
'__getattr__', '__setattr__',
'__init__', '__new__', '__prepare__'
'__instancecheck__', '__subclasscheck__',
'__del__'
))
_calculate_return_value = {
'__hash__': lambda self: object.__hash__(self),
'__str__': lambda self: object.__str__(self),
'__sizeof__': lambda self: object.__sizeof__(self),
'__unicode__': lambda self: unicode(object.__str__(self)),
}
_return_values = {
'__lt__': NotImplemented,
'__gt__': NotImplemented,
'__le__': NotImplemented,
'__ge__': NotImplemented,
'__int__': 1,
'__contains__': False,
'__len__': 0,
'__exit__': False,
'__complex__': 1j,
'__float__': 1.0,
'__bool__': True,
'__nonzero__': True,
'__oct__': '1',
'__hex__': '0x1',
'__long__': long(1),
'__index__': 1,
}
def _get_eq(self):
def __eq__(other):
ret_val = self.__eq__._mock_return_value
if ret_val is not DEFAULT:
return ret_val
return self is other
return __eq__
def _get_ne(self):
def __ne__(other):
if self.__ne__._mock_return_value is not DEFAULT:
return DEFAULT
return self is not other
return __ne__
def _get_iter(self):
def __iter__():
ret_val = self.__iter__._mock_return_value
if ret_val is DEFAULT:
return iter([])
# if ret_val was already an iterator, then calling iter on it should
# return the iterator unchanged
return iter(ret_val)
return __iter__
_side_effect_methods = {
'__eq__': _get_eq,
'__ne__': _get_ne,
'__iter__': _get_iter,
}
def _set_return_value(mock, method, name):
fixed = _return_values.get(name, DEFAULT)
if fixed is not DEFAULT:
method.return_value = fixed
return
return_calulator = _calculate_return_value.get(name)
if return_calulator is not None:
try:
return_value = return_calulator(mock)
except AttributeError:
# XXXX why do we return AttributeError here?
# set it as a side_effect instead?
return_value = AttributeError(name)
method.return_value = return_value
return
side_effector = _side_effect_methods.get(name)
if side_effector is not None:
method.side_effect = side_effector(mock)
class MagicMixin(object):
def __init__(self, *args, **kw):
# 添加所有未存在的魔术方法
self._mock_set_magics() # make magic work for kwargs in init
# 调用其他父类的__init__方法，添加_mock_methods方法
_safe_super(MagicMixin, self).__init__(*args, **kw)
# 修复被其他父类__init__方法破坏的mock方法
self._mock_set_magics() # fix magic broken by upper level init
def _mock_set_magics(self):
these_magics = _magics
# 第一次执行的时候_mock_methods是None
if getattr(self, "_mock_methods", None) is not None:
these_magics = _magics.intersection(self._mock_methods)
#these_magics=mock的魔术方法
remove_magics = set()
remove_magics = _magics - these_magics
for entry in remove_magics:
if entry in type(self).__dict__:
# remove unneeded magic methods
# 删除没mock的其他魔术方法
delattr(self, entry)
# don't overwrite existing attributes if called a second time
# 添加mock魔术方法时不覆盖已存在的方法
these_magics = these_magics - set(type(self).__dict__)
_type = type(self)
for entry in these_magics:
# 添加、修复所有魔术方法
setattr(_type, entry, MagicProxy(entry, self))
class NonCallableMagicMock(MagicMixin, NonCallableMock):
"""A version of `MagicMock` that isn't callable."""
def mock_add_spec(self, spec, spec_set=False):
"""Add a spec to a mock. `spec` can either be an object or a
list of strings. Only attributes on the `spec` can be fetched as
attributes from the mock.
If `spec_set` is True then only attributes on the spec can be set."""
self._mock_add_spec(spec, spec_set)
self._mock_set_magics()
class MagicMock(MagicMixin, Mock):
u"""带魔术方法的mock类.
MagicMock is a subclass of Mock with default implementations
of most of the magic methods. You can use MagicMock without having to
configure the magic methods yourself.
If you use the `spec` or `spec_set` arguments then *only* magic
methods that exist in the spec will be created.
Attributes and the return value of a `MagicMock` will also be `MagicMocks`.
"""
def mock_add_spec(self, spec, spec_set=False):
"""Add a spec to a mock. `spec` can either be an object or a
list of strings. Only attributes on the `spec` can be fetched as
attributes from the mock.
If `spec_set` is True then only attributes on the spec can be set."""
self._mock_add_spec(spec, spec_set)
self._mock_set_magics()
class MagicProxy(object):
u"""魔术代理类."""
def __init__(self, name, parent):
self.name = name
self.parent = parent
def __call__(self, *args, **kwargs):
# 魔术方法调用
m = self.create_mock()
return m(*args, **kwargs)
def create_mock(self):
entry = self.name
parent = self.parent
# 创建了一个Mock对象
m = parent._get_child_mock(name=entry, _new_name=entry,
_new_parent=parent)
setattr(parent, entry, m)
# 设置魔术方法返回值
_set_return_value(parent, m, entry)
return m
def __get__(self, obj, _type=None):
return self.create_mock()
class _ANY(object):
"""跟任何值比较都相等"""
"A helper object that compares equal to everything."
def __eq__(self, other):
return True
def __ne__(self, other):
return False
def __repr__(self):
return ''
ANY = _ANY()
def _format_call_signature(name, args, kwargs):
message = '%s(%%s)' % name
formatted_args = ''
args_string = ', '.join([repr(arg) for arg in args])
def encode_item(item):
if six.PY2 and isinstance(item, unicode):
return item.encode("utf-8")
else:
return item
kwargs_string = ', '.join([
'%s=%r' % (encode_item(key), value) for key, value in sorted(kwargs.items())
])
if args_string:
formatted_args = args_string
if kwargs_string:
if formatted_args:
formatted_args += ', '
formatted_args += kwargs_string
return message % formatted_args
class _Call(tuple):
"""
A tuple for holding the results of a call to a mock, either in the form
`(args, kwargs)` or `(name, args, kwargs)`.
If args or kwargs are empty then a call tuple will compare equal to
a tuple without those values. This makes comparisons less verbose::
_Call(('name', (), {})) == ('name',)
_Call(('name', (1,), {})) == ('name', (1,))
_Call(((), {'a': 'b'})) == ({'a': 'b'},)
The `_Call` object provides a useful shortcut for comparing with call::
_Call(((1, 2), {'a': 3})) == call(1, 2, a=3)
_Call(('foo', (1, 2), {'a': 3})) == call.foo(1, 2, a=3)
If the _Call has no name then it will match any name.
"""
def __new__(cls, value=(), name=None, parent=None, two=False,
from_kall=True):
name = ''
args = ()
kwargs = {}
_len = len(value)
if _len == 3:
name, args, kwargs = value
elif _len == 2:
first, second = value
if isinstance(first, basestring):
name = first
if isinstance(second, tuple):
args = second
else:
kwargs = second
else:
args, kwargs = first, second
elif _len == 1:
value, = value
if isinstance(value, basestring):
name = value
elif isinstance(value, tuple):
args = value
else:
kwargs = value
if two:
return tuple.__new__(cls, (args, kwargs))
return tuple.__new__(cls, (name, args, kwargs))
def __init__(self, value=(), name=None, parent=None, two=False,
from_kall=True):
self.name = name
self.parent = parent
self.from_kall = from_kall
def __eq__(self, other):
if other is ANY:
return True
try:
len_other = len(other)
except TypeError:
return False
self_name = ''
if len(self) == 2:
self_args, self_kwargs = self
else:
self_name, self_args, self_kwargs = self
other_name = ''
if len_other == 0:
other_args, other_kwargs = (), {}
elif len_other == 3:
other_name, other_args, other_kwargs = other
elif len_other == 1:
value, = other
if isinstance(value, tuple):
other_args = value
other_kwargs = {}
elif isinstance(value, basestring):
other_name = value
other_args, other_kwargs = (), {}
else:
other_args = ()
other_kwargs = value
elif len_other == 2:
# could be (name, args) or (name, kwargs) or (args, kwargs)
first, second = other
if isinstance(first, basestring):
other_name = first
if isinstance(second, tuple):
other_args, other_kwargs = second, {}
else:
other_args, other_kwargs = (), second
else:
other_args, other_kwargs = first, second
else:
return False
if self_name and other_name != self_name:
return False
# this order is important for ANY to work!
return (other_args, other_kwargs) == (self_args, self_kwargs)
def __ne__(self, other):
return not self.__eq__(other)
def __call__(self, *args, **kwargs):
if self.name is None:
return _Call(('', args, kwargs), name='()')
name = self.name + '()'
return _Call((self.name, args, kwargs), name=name, parent=self)
def __getattr__(self, attr):
if self.name is None:
return _Call(name=attr, from_kall=False)
name = '%s.%s' % (self.name, attr)
return _Call(name=name, parent=self, from_kall=False)
def count(self, *args, **kwargs):
return self.__getattr__('count')(*args, **kwargs)
def index(self, *args, **kwargs):
return self.__getattr__('index')(*args, **kwargs)
def __repr__(self):
if not self.from_kall:
name = self.name or 'call'
if name.startswith('()'):
name = 'call%s' % name
return name
if len(self) == 2:
name = 'call'
args, kwargs = self
else:
name, args, kwargs = self
if not name:
name = 'call'
elif not name.startswith('()'):
name = 'call.%s' % name
else:
name = 'call%s' % name
return _format_call_signature(name, args, kwargs)
def call_list(self):
"""For a call object that represents multiple calls, `call_list`
returns a list of all the intermediate calls as well as the
final call."""
vals = []
thing = self
while thing is not None:
if thing.from_kall:
vals.append(thing)
thing = thing.parent
return _CallList(reversed(vals))
call = _Call(from_kall=False)
def create_autospec(spec, spec_set=False, instance=False, _parent=None,
_name=None, **kwargs):
u"""创建autospec mock对象."""
"""Create a mock object using another object as a spec. Attributes on the
mock will use the corresponding attribute on the `spec` object as their
spec.
将其他对象作为spec参数，mock对象将包含spec对象中的属性
Functions or methods being mocked will have their arguments checked
to check that they are called with the correct signature.
被mock的方法将会检查方法签名
If `spec_set` is True then attempting to set attributes that don't exist
on the spec object will raise an `AttributeError`.
如果spec_set=True，则设置不存在的属性时将会报AttributeError异常
If a class is used as a spec then the return value of the mock (the
instance of the class) will have the same spec. You can use a class as the
spec for an instance object by passing `instance=True`. The returned mock
will only be callable if instances of the mock are callable.
`create_autospec` also takes arbitrary keyword arguments that are passed to
the constructor of the created mock."""
if _is_list(spec):
# can't pass a list instance to the mock constructor as it will be
# interpreted as a list of strings
spec = type(spec)
is_type = isinstance(spec, ClassTypes)
_kwargs = {'spec': spec}
if spec_set:
_kwargs = {'spec_set': spec}
elif spec is None:
# None we mock with a normal mock without a spec
_kwargs = {}
if _kwargs and instance:
_kwargs['_spec_as_instance'] = True
_kwargs.update(kwargs)
# 默认是MagicMock对象
Klass = MagicMock
if type(spec) in DescriptorTypes:
# descriptors don't have a spec
# because we don't know what type they return
_kwargs = {}
elif not _callable(spec):
# 根据spec选择mock类型
Klass = NonCallableMagicMock
elif is_type and instance and not _instance_callable(spec):
Klass = NonCallableMagicMock
_name = _kwargs.pop('name', _name)
_new_name = _name
if _parent is None:
# for a top level object no _new_name should be set
_new_name = ''
# 创建mock对象
mock = Klass(parent=_parent, _new_parent=_parent, _new_name=_new_name,
name=_name, **_kwargs)
if isinstance(spec, FunctionTypes):
# should only happen at the top level because we don't
# recurse for functions
# 添加签名检查
mock = _set_signature(mock, spec)
else:
# 设置参数检验方法
_check_signature(spec, mock, is_type, instance)
if _parent is not None and not instance:
_parent._mock_children[_name] = mock
if is_type and not instance and 'return_value' not in kwargs:
mock.return_value = create_autospec(spec, spec_set, instance=True,
_name='()', _parent=mock)
for entry in dir(spec):
# 设置对象属性
if _is_magic(entry):
# MagicMock already does the useful magic methods for us
continue
# XXXX do we need a better way of getting attributes without
# triggering code execution (?) Probably not - we need the actual
# object to mock it so we would rather trigger a property than mock
# the property descriptor. Likewise we want to mock out dynamically
# provided attributes.
# XXXX what about attributes that raise exceptions other than
# AttributeError on being fetched?
# we could be resilient against it, or catch and propagate the
# exception when the attribute is fetched from the mock
try:
original = getattr(spec, entry)
except AttributeError:
continue
kwargs = {'spec': original}
if spec_set:
kwargs = {'spec_set': original}
if not isinstance(original, FunctionTypes):
new = _SpecState(original, spec_set, mock, entry, instance)
mock._mock_children[entry] = new
else:
parent = mock
if isinstance(spec, FunctionTypes):
parent = mock.mock
skipfirst = _must_skip(spec, entry, is_type)
kwargs['_eat_self'] = skipfirst
new = MagicMock(parent=parent, name=entry, _new_name=entry,
_new_parent=parent,
**kwargs)
mock._mock_children[entry] = new
# 设置方法签名检查
_check_signature(original, new, skipfirst=skipfirst)
# so functions created with _set_signature become instance attributes,
# *plus* their underlying mock exists in _mock_children of the parent
# mock. Adding to _mock_children may be unnecessary where we are also
# setting as an instance attribute?
if isinstance(new, FunctionTypes):
setattr(mock, entry, new)
return mock
def _must_skip(spec, entry, is_type):
"""
Return whether we should skip the first argument on spec's `entry`
attribute.
"""
if not isinstance(spec, ClassTypes):
if entry in getattr(spec, '__dict__', {}):
# instance attribute - shouldn't skip
return False
spec = spec.__class__
if not hasattr(spec, '__mro__'):
# old style class: can't have descriptors anyway
return is_type
for klass in spec.__mro__:
result = klass.__dict__.get(entry, DEFAULT)
if result is DEFAULT:
continue
if isinstance(result, (staticmethod, classmethod)):
return False
elif isinstance(getattr(result, '__get__', None), MethodWrapperTypes):
# Normal method => skip if looked up on type
# (if looked up on instance, self is already skipped)
return is_type
else:
return False
# shouldn't get here unless function is a dynamically provided attribute
# XXXX untested behaviour
return is_type
def _get_class(obj):
try:
return obj.__class__
except AttributeError:
# it is possible for objects to have no __class__
return type(obj)
class _SpecState(object):
def __init__(self, spec, spec_set=False, parent=None,
name=None, ids=None, instance=False):
self.spec = spec
self.ids = ids
self.spec_set = spec_set
self.parent = parent
self.instance = instance
self.name = name
FunctionTypes = (
# python function
type(create_autospec),
# instance method
type(ANY.__eq__),
)
MethodWrapperTypes = (
type(ANY.__eq__.__get__),
)
file_spec = None
def _iterate_read_data(read_data):
"""迭代读取器"""
# Helper for mock_open:
# Retrieve lines from read_data via a generator so that separate calls to
# readline, read, and readlines are properly interleaved
sep = b'\n' if isinstance(read_data, bytes) else '\n'
data_as_list = [l + sep for l in read_data.split(sep)]
if data_as_list[-1] == sep:
# If the last line ended in a newline, the list comprehension will have an
# extra entry that's just a newline. Remove this.
data_as_list = data_as_list[:-1]
else:
# If there wasn't an extra newline by itself, then the file being
# emulated doesn't have a newline to end the last line remove the
# newline that our naive format() added
data_as_list[-1] = data_as_list[-1][:-1]
for line in data_as_list:
yield line
def mock_open(mock=None, read_data=''):
"""打开文件补丁"""
"""
A helper function to create a mock to replace the use of `open`. It works
for `open` called directly or used as a context manager.
The `mock` argument is the mock object to configure. If `None` (the
default) then a `MagicMock` will be created for you, with the API limited
to methods or attributes available on standard file handles.
`read_data` is a string for the `read` methoddline`, and `readlines` of the
file handle to return. This is an empty string by default.
"""
def _readlines_side_effect(*args, **kwargs):
if handle.readlines.return_value is not None:
return handle.readlines.return_value
return list(_state[0])
def _read_side_effect(*args, **kwargs):
if handle.read.return_value is not None:
return handle.read.return_value
return type(read_data)().join(_state[0])
def _readline_side_effect():
if handle.readline.return_value is not None:
while True:
yield handle.readline.return_value
for line in _state[0]:
yield line
global file_spec
if file_spec is None:
# set on first use
if six.PY3:
import _io
file_spec = list(set(dir(_io.TextIOWrapper)).union(set(dir(_io.BytesIO))))
else:
file_spec = file
if mock is None:
mock = MagicMock(name='open', spec=open)
handle = MagicMock(spec=file_spec)
handle.__enter__.return_value = handle
_state = [_iterate_read_data(read_data), None]
handle.write.return_value = None
handle.read.return_value = None
handle.readline.return_value = None
handle.readlines.return_value = None
handle.read.side_effect = _read_side_effect
_state[1] = _readline_side_effect()
handle.readline.side_effect = _state[1]
handle.readlines.side_effect = _readlines_side_effect
def reset_data(*args, **kwargs):
_state[0] = _iterate_read_data(read_data)
if handle.readline.side_effect == _state[1]:
# 在没有更改的情况下才设置
# Only reset the side effect if the user hasn't overridden it.
_state[1] = _readline_side_effect()
handle.readline.side_effect = _state[1]
return DEFAULT
mock.side_effect = reset_data
mock.return_value = handle
return mock
class PropertyMock(Mock):
u"""给属性打补丁"""
"""
A mock intended to be used as a property, or other descriptor, on a class.
`PropertyMock` provides `__get__` and `__set__` methods so you can specify
a return value when it is fetched.
Fetching a `PropertyMock` instance from an object calls the mock, with
no args. Setting it calls the mock with the value being set.
"""
def _get_child_mock(self, **kwargs):
return MagicMock(**kwargs)
def __get__(self, obj, obj_type):
return self()
def __set__(self, obj, val):
self(val)
总结：mock源码中用到了python中一些比较高级的语法糖，比如lambda生成一个匿名函数，有yield的函数已不是一个函数，而是一个生产器，用于生成可迭代对象，有next方法，可用于循环迭代中，type的一个实例就是一个类，还有就是涉及一些魔术方法，比如调用__call__，上下文管理__enter__、__exit__，创建对象__new__，初始化对象__init__，取得、设置属性__getattr__、__setattr__，还有大量使用了python装饰器。mock的实现原理主要是调用实际方法前调用__enter__给指定对象打补丁，并保存原始对象，方法调用后调用__exit__进行原始对象恢复，其中并覆写Mock对象的__call__使可以统计调用情况，覆写__getattr__可访问任意属性，autospec情况下获取函数签名进行参数检查。mock常用的就是mock.patch装饰器，可以作用在整个测试类上，也可以作用在单个测试方法上，当作用在测试类上时，会给测试类所有已test开头的测试方法都打上补丁。除了mock.patch，还提供一些其他实用工具，比如mock.patch.object给指定对象中的属性打补丁，patch.dict给dict的值打补丁，patch.multiple同时给一个对象的多个属性打补丁，patch.stopall取消所有补丁，mock_open模拟文件打开读取操作。