compose-testing

Compose / Kotlin Android Testing

Compose UI tests

class ProfileScreenTest {

    @get:Rule
    val rule = createComposeRule()

    @Test
    fun showsLoading() {
        rule.setContent {
            AppTheme { ProfileScreen(ProfileUiState.Loading, onIntent = {}) }
        }
        rule.onNodeWithContentDescription("Loading").assertIsDisplayed()
    }

    @Test
    fun showsUserName_onSuccess() {
        val user = User("alice", "Alice", "[email protected]")
        rule.setContent {
            AppTheme { ProfileScreen(ProfileUiState.Success(user), onIntent = {}) }
        }
        rule.onNodeWithText("Alice").assertIsDisplayed()
        rule.onNodeWithText("[email protected]").assertIsDisplayed()
    }

    @Test
    fun invokesOnIntent_whenButtonClicked() {
        val user = User("alice", "Alice", "[email protected]")
        var intent: ProfileIntent? = null
        rule.setContent {
            AppTheme {
                ProfileScreen(ProfileUiState.Success(user), onIntent = { intent = it })
            }
        }
        rule.onNodeWithText("Refresh").performClick()
        assertEquals(ProfileIntent.Refresh, intent)
    }
}

Test the stateless Screen composable. It takes state and lambdas, so the test never needs a ViewModel.

Semantic matchers

Prefer semantic queries over node-tree introspection:

• onNodeWithText("Alice") - visible text content.
• onNodeWithContentDescription("Profile avatar") - for icons/images.
• onNodeWithTag("submit-button") - via Modifier.testTag(...) (use sparingly; tags are not visible to users).
• onAllNodesWithText(...) - when multiple nodes match.

Custom matchers:

rule.onNode(hasText("Save") and hasClickAction()).performClick()

ViewModel tests with runTest + Turbine

class ProfileViewModelTest {

    @get:Rule
    val mainDispatcherRule = MainDispatcherRule()  // sets Dispatchers.Main to a test dispatcher

    @Test
    fun emitsSuccess_whenRepoReturnsUser() = runTest {
        val user = User("alice", "Alice", "[email protected]")
        val repo = FakeProfileRepository(user = user)
        // Build the route's SavedStateHandle via navigation-testing so toRoute<Profile>() works.
        val savedState = Profile("alice").let {
            SavedStateHandle().apply { set("userId", "alice") }  // see note below
        }
        val vm = ProfileViewModel(repo, savedState)

        vm.state.test {
            assertEquals(ProfileUiState.Loading, awaitItem())
            val item = awaitItem()
            assertTrue(item is ProfileUiState.Success)
            assertEquals("Alice", (item as ProfileUiState.Success).user.name)
            cancelAndIgnoreRemainingEvents()
        }
    }
}