Simple Espresso Test Setup / Basic Test

SimpleEspressoTest.kt

@RunWith(AndroidJUnit4::class)
class BaseMainActivityTest {

    @get:Rule
    var activityRule = ActivityTestRule(MainActivity::class.java)

    // the context is often needed in more complex Espresso tests
    protected val context: Context by lazy { activityRule.activity }
    
    @Test
    fun greeterSaysHello() {
        onView(withId(R.id.name_field)).perform(typeText("Steve"))
        onView(withId(R.id.greet_button)).perform(click())
        onView(withText("Hello Steve!")).check(matches(isDisplayed()))
    }
}