Jetpack Compose UI testing

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Introduction

Jetpack Compose, Android’s modern UI toolkit, has its own testing APIs. Google’s documentation explains the key concepts: semantics give meaning to UI so tests can interact with specific elements; testing APIs let you find elements, verify their attributes and perform user actions; and synchronisation means Compose tests wait for the UI to be idle automatically. The docs also cover a cheatsheet, test configuration and execution, interoperability with views, common patterns and debugging.

Tests use a rule created with createComposeRule() (or createAndroidComposeRule<Activity>() when activity access is needed), set content with setContent { ... }, then find nodes with finders such as onNodeWithText, onNodeWithTag and onNodeWithContentDescription, perform actions like performClick() and performTextInput(), and assert with assertIsDisplayed(), assertTextEquals() and others. The dependencies are androidx.compose.ui:ui-test-junit4 plus ui-test-manifest for createComposeRule. The same tests can run as instrumented tests on devices or as local tests with Robolectric, and frameworks such as Kaspresso and Roborazzi build on these APIs.

For debugging, printToLog() dumps the semantics tree, and the merged versus unmerged tree options explain why a finder matches or misses a node.

Features

1. Semantics-based finders: Find nodes by text, tag or description.
2. Automatic synchronisation: Waits for Compose to be idle.
3. Rich assertions and actions: Click, input, scroll and assert.
4. Device or JVM: Run on emulators or with Robolectric.

Pros

1. Free: Part of AndroidX.
2. Built-in sync: Less flakiness from timing issues.

Cons

1. Semantics required: Custom components need proper semantics or test tags.
2. Compose only: View-based screens need Espresso.

Usage and Links (Example)

androidTestImplementation("androidx.compose.ui:ui-test-junit4:<compose_version>")
debugImplementation("androidx.compose.ui:ui-test-manifest:<compose_version>")

class CounterTest {
    @get:Rule val composeTestRule = createComposeRule()

    @Test
    fun incrementsCounter() {
        composeTestRule.setContent { Counter() }
        composeTestRule.onNodeWithText("Increment").performClick()
        composeTestRule.onNodeWithTag("count").assertTextEquals("1")
    }
}

Resources:

• Jetpack Compose UI testing website

Pricing

Free and open source as part of Jetpack Compose (Apache-2.0).

Recommended for?

1. Android teams using Jetpack Compose.
2. Teams wanting fast Compose tests on the JVM via Robolectric.

Conclusion

Compose’s testing APIs make UI tests concise and reliable, and they are the foundation for most modern Android UI testing.