Logs all state changes so you can find out what causes a self-invalidating loop in your app in case you keep running into timeouts in your tests

ObserveStateChangesCreateComposeRule.kt

// Use this template if you use ComposeTestRule (createComposeRule())
// Use the other template if you use ComposeUiTest (runComposeUiTest())

private val TAG = "TEST_TAG"
private var I = 0 // add a sequence number to every log message for disambiguation
private var unregisterApplyObserver: ObserverHandle? = null
private var unregisterWriteObserver: ObserverHandle? = null

@Test
fun test() {
    // your test here
}

@Before
fun setup() {
    unregisterApplyObserver = Snapshot.registerApplyObserver { mutatedObjects, snapshot ->
        val colon = if (mutatedObjects.isNotEmpty()) ":" else ""
        Log.i(TAG, "[${I++}] applying snapshot$colon")
        for (obj in mutatedObjects) {
            Log.d(TAG, "[${I++}]   modified: $obj")
        }
    }
    unregisterWriteObserver = Snapshot.registerGlobalWriteObserver { mutatedObject ->
        Log.d(TAG, "[${I++}] writing in snapshot: $mutatedObject")
    }
}

@After
fun tearDown() {
    unregisterApplyObserver?.dispose()
    unregisterWriteObserver?.dispose()
}

ObserveStateChangesRunComposeUiTest.kt

// Use this template if you use ComposeUiTest (runComposeUiTest())
// Use the other template if you use ComposeTestRule (createComposeRule())

private val TAG = "TEST_TAG"
private var I = 0 // add a sequence number to every log message for disambiguation

@Test
fun test() = runComposeUiTest {
    withApplyAndWriteObserver {
        // your test here
    }
}

private inline fun withApplyAndWriteObserver(block: () -> Any) {
    var unregisterApplyObserver: ObserverHandle? = null
    var unregisterWriteObserver: ObserverHandle? = null
    try {
        unregisterApplyObserver = Snapshot.registerApplyObserver { mutatedObjects, snapshot ->
            Log.i(TAG, "[${I++}] applying snapshot")
            for (obj in mutatedObjects) {
                Log.d(TAG, "[${I++}]   modified: $obj")
            }
        }
        unregisterWriteObserver = Snapshot.registerGlobalWriteObserver { mutatedObject ->
            Log.d(TAG, "[${I++}] writing in snapshot: $mutatedObject")
        }
        block()
    } finally {
        unregisterApplyObserver?.dispose()
        unregisterWriteObserver?.dispose()
    }
}