python - 什么是 spec 和 spec_set

Question

我正在使用 Mock 1.0.1 python。 在路径函数定义中有两个可选参数名称 spec 和 spec_set(也称为 auto_spec)

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

我已经通读了文档，但没有找到对它们的解释。也许他们是测试条款？如果有人能提供信息就更好了，谢谢。

Answer 1

unittest.mock在 Python 3.x 中与 mock 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 spec 和spec_set 的区别。

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

例子:

>>> 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.c      # get -> success (although c is not in the spec)
9



>>> 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'