JUnit Tests

This tutorial lets you test a Kotlin application and use Koin inject and retrieve your components.

Get the code

info

The source code is available at on Github

Gradle Setup

First, add the Koin dependency like below:

dependencies {
    // Koin testing tools
    testCompile "io.insert-koin:koin-test:$koin_version"
    // Needed JUnit version
    testCompile "io.insert-koin:koin-test-junit4:$koin_version"
}

Declared dependencies

We reuse the koin-core getting-started project, to use the koin module:

val helloModule = module {
    single { HelloMessageData() }
    single { HelloServiceImpl(get()) as HelloService }
}

Writing our first Test

To make our first test, let's write a simple Junit test file and extend it with KoinTest. We will be able then, to use by inject() operators.

class HelloAppTest : KoinTest {

    val model by inject<HelloMessageData>()
    val service by inject<HelloService>()

    @get:Rule
    val koinTestRule = KoinTestRule.create {
        printLogger()
        modules(helloModule)
    }

    @Test
    fun `unit test`() {
        val helloApp = HelloApplication()
        helloApp.sayHello()

        assertEquals(service, helloApp.helloService)
        assertEquals("Hey, ${model.message}", service.hello())
    }
}

We use the Koin KoinTestRule rule to start/stop our Koin context

You can even make Mocks directly into MyPresenter, or test MyRepository. Those components doesn't have any link with Koin API.

class HelloMockTest : KoinTest {

    @get:Rule
    val koinTestRule = KoinTestRule.create {
        printLogger(Level.DEBUG)
        modules(helloModule)
    }

    @get:Rule
    val mockProvider = MockProviderRule.create { clazz ->
        Mockito.mock(clazz.java)
    }

    @Test
    fun `mock test`() {
        val service = declareMock<HelloService> {
            given(hello()).willReturn("Hello Mock")
        }

        HelloApplication().sayHello()

        Mockito.verify(service,times(1)).hello()
    }
}