pytest monkeypatch

what is it?

one of the default pytest fixtures that can be used for mocking and patching

monkeypatch
    The returned ``monkeypatch`` fixture provides these
    helper methods to modify objects, dictionaries or os.environ::
 
        monkeypatch.setattr(obj, name, value, raising=True)
        monkeypatch.delattr(obj, name, raising=True)
        monkeypatch.setitem(mapping, name, value)
        monkeypatch.delitem(obj, name, raising=True)
        monkeypatch.setenv(name, value, prepend=False)
        monkeypatch.delenv(name, raising=True)
        monkeypatch.syspath_prepend(path)
        monkeypatch.chdir(path)
 
    All modifications will be undone after the requesting
    test function or fixture has finished. The ``raising``
    parameter determines if a KeyError or AttributeError
    will be raised if the set/deletion operation has no target.