Test against screen configuration changes with the Espresso Device API

Use the Espresso Device API to test your app when the device undergoes common configuration changes, such as rotation and screen unfolding. The Espresso Device API lets you simulate these configuration changes on a virtual device and executes your tests synchronously, so only one UI action or assertion happens at a time and your test results are more reliable. If you're new to writing UI tests with Espresso, see its documentation.

To use the Espresso Device API, you need the following:

• Android Studio Iguana or higher
• Android Gradle plugin 8.3 or higher
• Android Emulator 33.1.10 or higher
• Android virtual device that runs API level 24 or higher

Set up your project for the Espresso Device API

To set up your project so it supports the Espresso Device API, do the following:

1. To let the test pass commands to the test device, add the INTERNET and ACCESS_NETWORK_STATE permissions to the manifest file in the androidTest source set:

     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     

2. Enable the enableEmulatorControl experimental flag in the gradle.properties file:

     android.experimental.androidTest.enableEmulatorControl=true
     

3. Enable the emulatorControl option in the module-level build script:

   Kotlin

     testOptions {
       emulatorControl {
         enable = true
       }
     }
     

   Groovy

     testOptions {
       emulatorControl {
         enable = true
       }
     }
     

4. In the module-level build script, import the Espresso Device library into your project:

   Kotlin

     dependencies {
       androidTestImplementation("androidx.test.espresso:espresso-device:1.0.1")
     }
     

   Groovy

     dependencies {
       androidTestImplementation 'androidx.test.espresso:espresso-device:1.0.1'
     }
     

Test against common configuration changes

The Espresso Device API has multiple screen orientation and foldable states that you can use to simulate device configuration changes.

Test against screen rotation

Here's an example of how to test what happens to your app when the device screen rotates:

1. First, for a consistent starting state set the device to portrait mode:

     import androidx.test.espresso.device.action.ScreenOrientation
     import androidx.test.espresso.device.rules.ScreenOrientationRule
     ...
     @get:Rule
     val screenOrientationRule: ScreenOrientationRule = ScreenOrientationRule(ScreenOrientation.PORTRAIT)
     

2. Create a test that sets the device to landscape orientation during test execution:

     @Test
     fun myRotationTest() {
       ...
       // Sets the device to landscape orientation during test execution.
       onDevice().setScreenOrientation(ScreenOrientation.LANDSCAPE)
       ...
     }
     

3. After the screen rotates, check that the UI adapts to the new layout as expected.

     @Test
     fun myRotationTest() {
       ...
       // Sets the device to landscape orientation during test execution.
       onDevice().setScreenOrientation(ScreenOrientation.LANDSCAPE)
       composeTestRule.onNodeWithTag("NavRail").assertIsDisplayed()
       composeTestRule.onNodeWithTag("BottomBar").assertDoesNotExist()
     }
     

Test against screen unfolding

Here's an example of how to test what happens to your app if it's on a foldable device and the screen unfolds:

1. First, test with the device in the folded state by calling onDevice().setClosedMode(). Make sure that your app's layout adapts to the compact screen width.

     @Test
     fun myUnfoldedTest() {
       onDevice().setClosedMode()
       composeTestRule.onNodeWithTag("BottomBar").assetIsDisplayed()
       composeTestRule.onNodeWithTag("NavRail").assetDoesNotExist()
       ...
     }
     

2. To transition to a fully unfolded state, call onDevice().setFlatMode(). Check that the app’s layout adapts to the expanded size class.

     @Test
     fun myUnfoldedTest() {
       onDevice().setClosedMode()
       ...
       onDevice().setFlatMode()
       composeTestRule.onNodeWithTag("NavRail").assertIsDisplayed()
       composeTestRule.onNodeWithTag("BottomBar").assetDoesNotExist()
     }
     

Specify what devices your tests need

If you're running a test that performs folding actions on a device that isn't foldable, the test will likely fail. To execute only the tests that are relevant to the running device, use the @RequiresDeviceMode annotation. The test runner automatically skips running tests on devices that don't support the configuration being tested. You can add the device requirement rule to each test or an entire test class.

For example, to specify that a test should only be run on devices that support unfolding to a flat configuration, add the following @RequiresDeviceMode code to your test:

@Test
@RequiresDeviceMode(mode = FLAT)
fun myUnfoldedTest() {
  ...
}