Sometimes tests need to invoke functionality which depends on global settings or which invokes code which cannot be easily tested such as network access. The monkeypatch fixture helps you to safely set/delete an attribute, dictionary item or environment variable, or to modify sys.path for importing.

The monkeypatch fixture provides these helper methods for safely patching and mocking functionality in tests:

• 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=None)
• monkeypatch.delenv(name, raising=True)
• monkeypatch.syspath_prepend(path)
• monkeypatch.chdir(path)
• monkeypatch.context()

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 target of the set/deletion operation does not exist.