MainActivityTest.kt

@RunWith(AndroidJUnit4::class)
class MainActivityTest {
@Rule @JvmField var activityActivityTestRule = ActivityTestRule(MainActivity::class.java)
@Test
    fun setUserName() {
        onView(withId(R.id.name_field)).perform(typeText("Vivek Maskara"))
        onView(withId(R.id.set_user_name)).perform(click())
        onView(withText("Hello Vivek Maskara!")).check(matches(isDisplayed()))
    }
}