Activity testing on JUnit 5 is built on top of the Android ActivityScenario API. This guide is a great introduction to how that particular API can be used to drive an instrumentation test.

The android-test-core library provided by this repository gives developers an entry point to the ActivityScenario through an Extension Point. Its usage is analogous to how the old ActivityScenarioRule works in a JUnit 4 context.

Here is a minimal example:

class MyActivityTest {
    @JvmField
    @RegisterExtension
    val scenarioExtension = ActivityScenarioExtension.launch<MyActivity>()
    @Test
    fun myTest() {
        val scenario = scenarioExtension.scenario
        // Do something with the scenario here...
    }
}

Instead of being annotated with JUnit 4's @Rule, the extension is annotated with @RegisterExtension. For tests written in Kotlin, the @JvmField is also required, so that the runtime can process the extension properly.

When you use the ActivityScenarioExtension, you can also take advantage of JUnit 5's "parameter resolution" feature. A scenario can be passed to a test method directly as a parameter, saving you one line of code inside each test:

class MyActivityTest {
    @JvmField
    @RegisterExtension
    val scenarioExtension = ActivityScenarioExtension.launch<MyActivity>()
    @Test
    fun myTest(scenario: ActivityScenario<MyActivity>) {
        // Do something with the scenario here...
    }
}

Note the method parameter of the myTest() method.

For more information on ActivityScenario, please refer to the official documentation on the topic.