Sometimes mocking, even to check error paths, isn't a lot of work. It depends.
A lot of times designing your interfaces to support mock objects more easily improves them in other ways; if you pass in a file object instead of a filename, for example, not only does it become easier to pass in a mock object that raises an error, but it also becomes easier to pass in a GzipFile object or an HTTPResponse object, and presto, your function now handles compressed data and data stored on a web server.
with patch.object(requests, "get") as get_mock:
with nose.tools.assert_raises(socket.error):
get_mock.side_effect = socket.error
inject_exception.call_api("http://example.com")
A lot of times designing your interfaces to support mock objects more easily improves them in other ways; if you pass in a file object instead of a filename, for example, not only does it become easier to pass in a mock object that raises an error, but it also becomes easier to pass in a GzipFile object or an HTTPResponse object, and presto, your function now handles compressed data and data stored on a web server.
Also, though, monkeypatching stuff in tests isn't hard in dynamic languages. Here's an example from https://echohack.medium.com/python-unit-testing-injecting-ex...: