The problem is writing unit tests and need to apply patches to selected objects in order to make assertions about how they were used in the test (e.g., assertions about being called with certain parameters, access to selected attributes, etc.).
To do so, the
unittest.mock.patch() function can be used to help with this problem. It’s a little unusual, but
patch() can be used as a decorator, a context manager, or stand-alone.
unittest.mock.patchas a decorator
Code #2: Using
unittest.mock.patch as a decorator
Code #3: Using
unittest.mock.patch to patch things manually.
Code #4: Stacking decorators and context managers to patch multiple objects
patch() works by taking an existing object with the fully qualified name that you provide and replacing it with a new value. The original value is then restored after the completion of the decorated function or context manager. By default, values are replaced with MagicMock instances.
Code #5 : Example
<MagicMock name='x' id='4314230032'> 42
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