什么是规格和规格

Question

我正在使用Mock 1.0.1python。 在路径函数定义中，有两个可选参数名spec和spec_set（也可以是auto_spec）

patch(target, new=DEFAULT, spec=None, create=False, spec_set=None, autospec=None, new_callable=None, **kwargs)

我已经通读了文件，但找不到任何解释。也许它们是测试的条件？如果有人能提供信息就好了，谢谢。

Answer 1

你可以在这里找到更多信息：http://www.voidspace.org.uk/downloads/mock-1.0.1.pdf

• 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 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.

Answer 2

Python 3.x中的^{}与^{}基本相同。

根据unittest.mock文档：

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 __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.

---

更新在spec和spec_set之间的差异。

使用spec可以设置未指定的属性，而使用spec_set则不允许设置未指定的属性。

示例：

>>> from unittest.mock import Mock
>>> class A:
...     def __init__(self, a, b):
...         self.a = a
...         self.b = b
...
>>> aobj = A(1, 2)



>>> m = Mock(spec=aobj)   # spec
>>> m.c   # get -> fail
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python3/3.6.0b4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/mock.py", line 582, in __getattr__
    raise AttributeError("Mock object has no attribute %r" % name)
AttributeError: Mock object has no attribute 'c'
>>> m.c = 9  # set -> success
>>>




>>> m = Mock(spec_set=aobj)   # spec_set
>>> m.a
<Mock name='mock.a' id='4544967400'>
>>> m.b
<Mock name='mock.b' id='4545493928'>
>>> m.c   # get -> fail
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python3/3.6.0b4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/mock.py", line 582, in __getattr__
    raise AttributeError("Mock object has no attribute %r" % name)
AttributeError: Mock object has no attribute 'c'
>>> m.c = 9  # set -> fail
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python3/3.6.0b4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/mock.py", line 688, in __setattr__
    raise AttributeError("Mock object has no attribute '%s'" % name)
AttributeError: Mock object has no attribute 'c'