Interoperability

Compose integrates with common testing frameworks.

Interoperability with Espresso

In a hybrid app, you can find Compose components inside view hierarchies and views inside Compose composables (via the AndroidView composable).

There are no special steps needed to match either type. You match views with Espresso's onView, and Compose elements with the ComposeTestRule.

@Test
fun androidViewInteropTest() {
    // Check the initial state of a TextView that depends on a Compose state.
    Espresso.onView(withText("Hello Views")).check(matches(isDisplayed()))
    // Click on the Compose button that changes the state.
    composeTestRule.onNodeWithText("Click here").performClick()
    // Check the new value.
    Espresso.onView(withText("Hello Compose")).check(matches(isDisplayed()))
}

Interoperability with UiAutomator

By default, composables are accessible from UiAutomator only by their convenient descriptors (displayed text, content description, etc.). If you want to access any composable that uses Modifier.testTag, you need to enable the semantic property testTagsAsResourceId for the particular composable's subtree. Enabling this behavior is useful for composables that don't have any other unique handle, such as scrollable composables (for example, LazyColumn).

Enable the semantic property only once high in your composables hierarchy to ensure all nested composables with Modifier.testTag are accessible from UiAutomator.

Scaffold(
    // Enables for all composables in the hierarchy.
    modifier = Modifier.semantics {
        testTagsAsResourceId = true
    }
){
    // Modifier.testTag is accessible from UiAutomator for composables nested here.
    LazyColumn(
        modifier = Modifier.testTag("myLazyColumn")
    ){
        // Content
    }
}

Any composable with the Modifier.testTag(tag) can be accessible with the use of By.res(resourceName) using the same tag as the resourceName.

val device = UiDevice.getInstance(getInstrumentation())

val lazyColumn: UiObject2 = device.findObject(By.res("myLazyColumn"))
// Some interaction with the lazyColumn.

Additional Resources

• Test apps on Android: The main Android testing landing page provides a broader view of testing fundamentals and techniques.
• Fundamentals of testing: Learn more about the core concepts behind testing an Android app.
• Local tests: You can run some tests locally, on your own workstation.
• Instrumented tests: It is good practice to also run instrumented tests. That is, tests that run directly on-device.
• Continuous integration: Continuous integration lets you integrate your tests into your deployment pipeline.
• Test different screen sizes: With some many devices available to users, you should test for different screen sizes.
• Espresso: While intended for View-based UIs, Espresso knowledge can still be helpful for some aspects of Compose testing.