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Comment by dboreham | Hacker News Reader

I've been doing this stuff (software) for a very long time and if it hadn't been invented by others, I'd never have thought of Mocking. It's that stupid of an idea. When I first came across it used in anger in a large project it took me a while to get my head around what was going on. When the penny dropped I remember a feeling of doom, like I had realized I was in The Matrix. Don't work there, and don't work with mock-people any more.

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I don't like mocking either, but there are periodically situations where I've found it useful. Sometimes there is a complex system (whether of your own design or not) that isn't amenable to integration/e2e testing, and the interesting parts can't be easily unit tested due to external or tightly coupled dependencies.

Of course you can always pick it apart and refactor so it can be unit tested, but sometimes the effort required makes mocking look pretty appealing.

With containerization it’s very quick to spin up test dependencies as well as part of your CICD. Why mock calls to a datastore when it’s super easy to spin up an ephemeral postgresql instance to test on?

> Why mock calls to a datastore when it’s super easy to spin up an ephemeral postgresql instance to test on?

It's actually super hard to get Postgres to fail, which is what you will be most interested in testing. Granted, you would probably use stubbing for that instead.

Because you have 40000 tests, and an in memory object means they can run in seconds. And the real thing runs in minutes.

Yup. Section "Easier to Test IO" in TFA.

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