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Suppose I have a Python class that I want to add an extra property to.
Is there any difference between
import path.MyClass
MyClass.foo = bar
and using something like :
import path.MyClass
setattr(MyClass, 'foo', bar)
?
If not, why do people seem to do the second rather than the first? (Eg. here http://concisionandconcinnity.blogspot.com/2008/10/chaining-monkey-patches-in-python.html )
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patch() unittest. mock provides a powerful mechanism for mocking objects, called patch() , which looks up an object in a given module and replaces that object with a Mock . Usually, you use patch() as a decorator or a context manager to provide a scope in which you will mock the target object.
Patching vs Mocking: Patching a function is adjusting it's functionality. In the context of unit testing we patch a dependency away; so we replace the dependency. Mocking is imitating. Usually we patch a function to use a mock we control instead of a dependency we don't control.
unittest. mock is a library for testing in Python. It allows you to replace parts of your system under test with mock objects and make assertions about how they have been used. unittest.
The statements are equivalent, but setattr might be used because it's the most dynamic choice of the two (with setattr you can use a variable for the attribute name.)
See: http://docs.python.org/library/functions.html#setattr
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