Testing - the official docs on compose recommend w...

# compose

[agrosner]

Testing - the official docs on compose recommend we run AndroidTest for our composables that run on a device. Also i have seen people mention robolectric in this channel to run a bunch of tests quickly.
We have a lot of modules in our company and CI would not efficiently handle all of the tests to run often on PRs with many or any emulators.

1. should we use robolectric even if its not perfect?
2. is there movement on making official headless compose unit tests that dont need a physical device (outside of robolectric) to verify basic ui interactions or snapshots

[madisp]

hey, IMHO for UI stuff you want to keep using espresso or something similar

[madisp]

for many modules and many tests have you considered cloud testing tools like firebase test lab?

[dorche]

I've not had a chance to play with it but
https://github.com/cashapp/paparazzi

[madisp]

paparazzi is great for screenshot testing indeed

[dorche]

Can you share any thoughts about it? How does it do the rendering? I'm thinking for a full compose app you could iterate over all your Previews and use paparazzi to generate screenshot tests? I've used facebook's "shot" library before, how does it compare?

[madisp]

I've only used it for normal layouts and afaik paparazzi is based on layoutlib (the renderer in Android Studio)

[agrosner]

We could consider that. But right now it's not an option. Good to cast a wide net on speed and performance too

[agrosner]

Paparrazi does that work with compose?

[agrosner]

Snapshot testing on compose could capture instructions and instead of executing them, serialize them either just compose hierarchy with parameters passed in (similar to jest + shallow snapshots on web)

[dorche]

Yeah Paparazzi has added compose support lately (as I said I’ve not tried it out yet, still using Shot). Serializing is a good shout, I’d be interested in how that turns out. In my current setup, the only instrumentation tests I have are snapshot tests (with the argument that all the logic is already covered by Unit Tests and given the State nature of Compose, a snapshot test for each State gives me enough confidence in the UI and I get all that for free from the Previews). No espresso faff either…

[agrosner]

Where do you see that? I don't see it in. Their changelogs

[dorche]

You'll need to use the snapshots repo, think its only from v1.0.0 onwards https://github.com/cashapp/paparazzi/pull/371