test_with_custom_koin_module.kt

private val loginModule = module {
    val credentialsValidator = LoginCredentialsValidator()
    val loginApi = InMemoryLoginApi()
    val loginRepository = RemoteLoginRepository(loginApi)
    viewModel {
        LoginViewModel(credentialsValidator, loginRepository)
    }
}

@Before
fun setUp() {
    loadKoinModules(loginModule)
    rule.launchActivity(Intent())
}

@Test
fun should_display_incorrect_credentials_error() {
    onView(withId(R.id.loginUsername)).perform(typeText("username"))
    onView(withId(R.id.loginPassword)).perform(typeText("password"))

    onView(withId(R.id.loginButton)).perform(click())

    onView(withId(R.id.textInfoLabel)).check(matches(withText("Incorrect Credentials")))
}

@After
fun tearDown() {
    unloadKoinModules(loginModule)
}