I finally solved my Compose testing problems after spending

Question

I finally solved my Compose testing problems after spending quite some time trying to track down some very obscure bugs With Compose when testing screens you call `composeTestRule setContent MyScreen ` if you ve written Compose UI tests you d be familiar with this If you need to run the tests against a particular activity for some reason you can use `androidComposeTestRule lt MyActivity gt ` In my case `MyActivity` calls `setContent MyScreen ` during `onCreate ` So what ends up happening is the test instantiates `MyActivity` which calls `setContent ` and the screen is composed with its ViewModel and various dependencies While this is happening the test calls its own `setContent ` and the screen is composed again in parallel This causes all kinds of nightmarish problems tl dr Make sure when testing Compose that you only call `setContent ` once per test And be careful about which `Activity` you use to host the test if you need one

Colton Idle · Answer

oof so if my activity already calls setContent I shouldnt call setContent in my test right

Tim Malseed · Answer

If your test uses `androidComposeTestRule` and so runs inside an Activity that already calls `setContent ` then calling `setContent ` again in your test can cause issues

Tim Malseed · Answer

So my advice isn t don t call `setContent ` in test But rather don t test against an Activity that calls `setContent ` My solution was to create another Activity just for test purposes And to keep this from prod I only declare this Activity in the debug AndroidManifest

Alex Vanyo · Answer

If you don t need a specific `Activity` you can use a plain `createComposeRule ` instead along with the `ui test manifest` dependency If you add it with `debugImplementation` this should function exactly like your test activity ```debugImplementation androidx compose ui ui test manifest $compose version ```

Tim Malseed · Answer

Yep This issue only occurs when you do need a specific Activity like when you re injecting stuff via Hilt

Colton Idle · Answer

Yeah I think I need a specific activity because I m trying to create a few like 5 critical path end to end tests So I actually want it to start my app and just assert some basic things

Colton Idle · Answer

And so therefore my end to end test wouldn t need to call set content since the activity already calls setConent

Tim Malseed · Answer

Yeah But when you want to test a Composable in isolation that s when you want to be able to call `setContent `

Tim Malseed · Answer

So there s like this very specific set of circumstances that can lead to a lot of pain sob

Colton Idle · Answer

So there s like this very specific set of circumstances that can lead to a lot of pain I think you ve summed up software engineering