UnitTests.md

Unit Tests with Koin

1 Intro

The aim of the document is to provide base indications on unit tests. Unit testing can be done in various ways and with different tools. We suggest to test your application with Koin in order to mock your test objects.

In the following paragraphs, I'll describe an example of a unit test with the ktAndroidArchitecture.

2.1 Preliminary actions

Gradle dependencies

android.defaultConfig {
     androidTestImplementation 'androidx.test:runner:1.2.0'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
     testImplementation 'org.mockito:mockito-core:2.23.0'
     testImplementation 'android.arch.core:core-testing:1.1.1'
     testImplementation 'com.jraska.livedata:testing-ktx:1.1.0'
     testImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:1.3.0"
     // Koin for Unit tests
     testImplementation "org.koin:koin-test:$koin_version"
}

2.2 UseCase test

In order to perform a UseCase test, you have to call the run() function of the UseCase providing the ActionParams inside the method signature. After that, you can perform all the assertion that are useful to you. In the following snippet we are testing the LoginUseCase.

class LoginUseCaseTest : KoinTest {

    @Before
    fun before() {
        startKoin {
            printLogger()
            modules(appModule)
        }
    }
    
    @After
    fun after() {
        stopKoin()
    }
    
    @Test
    fun runUseCase() = runBlockingTest {
        val email = "email"
        val password = "test"
        val params = LoginActionParams(email, password)
        val result = useCase.run(params)
        assert(result.isRight)
        var userLogged: UserLogged? = null
        result.map { res -> userLogged = res }
        delay(200)
        assertEquals(UserLogged(email), userLogged)
    }
    
    // further tests here
}

2.2 ViewModel test

In order to perform a ViewModel test, you have to create a method inside the real ViewModel.

class LoginViewModel(loginUseCase: LoginUseCase) : BaseViewModel() {

    fun login(username: String, password: String) {
        actionLogin.execute(LoginActionParams(username, password), viewModelScope)
    }
    
}

Then you can call the "login()" function inside the ViewModel test class.

class LoginViewModelTest : KoinTest {
    // Executes tasks in the Architecture Components in the same thread
    @get:Rule
    var instantTaskExecutorRule = InstantTaskExecutorRule()
    private val loginViewModelTest: LoginViewModel by inject()

    @Before
    fun before() {
        startKoin {
            printLogger()
            modules(appModule)
        }
    }

    @After
    fun after() {
        stopKoin()
    }

    @Test
    fun `testLogin`() {
        val testLifecycle = TestLifecycle.initialized()
        val email = "email"
        val password = "test"
        loginViewModelTest.login(email, password)
        testLifecycle.resume()
        val result = LiveDataTestUtil.getValue(loginViewModelTest.actionLogin, testLifecycle)
        assertEquals(UIUserLogged(email), result)
    }
    
     // further tests here
}

In the previous snippet, you can see the loginViewModelTest.login(email, password) used to test the ViewModel.

2.3 Repository test

In order to perform a Repository test, you have to inject the real repository through Koin. Then, inside the @Test annotated function, you can call the repository function that you want to test.

class AuthRepositoryTest : KoinTest {

    val repo: AuthRepository by inject()

    @Before
    fun before() {
        startKoin {
            printLogger()
            modules(appModule)
        }
    }
    
    @After
    fun after() {
        stopKoin()
    }
    
    @Test
    fun login() {
        val email = "email"
        val password = "test"
        val result = repo.login(email, password)
        assertEquals(UserLogged(email), result)
    }
    
}