What API mocking tool are Elixir teams using?

Hello,

What are you trying to mock in elixir? External APIs or your own API?

Bypass - for HTTP
Mimic - for in process APIs, things that [may] call modules which HTTP

I have been using Sham over Bypass for a while now.

Mimic for quick mocking

Mox occasionally.

When testing with something that uses Req, I just use the built in Req.Test things. Super handy.

Efx moves mocking in new direction: Efx - A library to declaratively write testable effects | Elixir Forum
I used in one of my pet projects

What were your impressions?

Hi @dimitarvp, biggest win compared to Mox (up to Efx the best option) is no hassle with configurations and precondition that boundary needs to have behaviour. In testing, you bind your boundary functions and you are good to go.

is no hassle with configurations

Mimic works in the same way too

Unique power of Efx is

Efx uses the fairly new ancestor-keys from the process dictionary to track down the bindings for tests event for child-processes and therefore, more tests can be implemented asynchronously.

I was about to say but got beaten to it: how is this different than Mimic?

Though I have to say: explicit or implicit marking of effects is very, VERY, welcome. Don’t get me wrong.

I glanced over Efx and yeah, just as I expected, it’s another way to NOT do proper dependency injection. Why are we so afraid to code against protocols and pass around structs which implement them?

Why are we so afraid to code against protocols

protocols are about polymorphism based on the struct type, whereas we’re discussing behavior that depends on the environment. For example, in test env we may want to avoid making real HTTP calls or spawning real processes.

Mox is a great fit when you’re abstracting an external dependency behind a behavior. But for testing internal implementations, I find e.g. Mimic much more convenient. It lets you mock internal modules without adding extra behaviors, configuration, or maintenance overhead