That really depends on the case in question and on the particulars of the codebase. I wouldn't recommend mocking http libraries, database calls etc. - that usu

That really depends on the case in question and on the particulars of the codebase. I wouldn't recommend mocking http libraries, database calls etc. - that usually leads to madness and impenetrable test setups. I would rather recommend to either use fake implementations (e.g. in-memory DB) or to only integration-test the boundaries of your interaction with the external system (that might or might not be hard to achieve). But I do like the pattern of wrapping calls to external APIs through a layer that I control - so that, for example, I may just write mailer.sendMessage(message) - and then that mailer interface seems like a good candidate for mocking.