Adding Compose to Existing Espresso Tests with createEmptyComposeRule()

As the documentation says, you can combine both Espresso and Compose in an Android instrumentation test. In order to interact with Compose in an instrumentation test you need a ComposeTestRule.

Problem

Typically you would create a ComposeTestRule with createComposeRule() in a part of your app that is compose only, but that will create a blank ComponentActivity and launch it showing a blank screen.

@get:Rule
val composeTestRule = createComposeRule()

This is great if you are looking to just use composeTestRule.setContent { Text("Hi")} in your test, but if you are integrating with an existing Espresso test, this will not be the case.

You could use the createAndroidComposeRule<MyActivity>(), however that will also use an ActivityTestRule underneath the hood and launch the Activity, which will change the behavior of your existing test. 🤔

@get:Rule
val composeTestRule = createAndroidComposeRule<MyActivity>()

Solution

If all you want to do is keep the Espresso test the same way it is, but also interact with some compose elements, use createEmptyComposeRule() and it will all work! 🎉

@get:Rule
val composeTestRule = createEmptyComposeRule()

Conclusion

Now you can interact with compose elements along with view elements, exactly like the documentation says. 😃

composeTestRule.onNodeWithText("Something").assertIsDisplayed()