Koin dependency override is not working in testing

Question

I'm new to testing and I adapted Koin as my dependency injection. my application is working fine. it's still having a login function. Here's my dependency class

Modules.kt

val applicationModule = module (override = true) {
    single { NetworkService.getInstance().getService(APIService::class.java) }
    single { PreferenceManager.getDefaultSharedPreferences(androidContext()) }
}

val activityModule = module {

    scope(named<LoginActivity>()) {
        scoped { (activity: LoginActivity) ->
            Navigation
                .findNavController(activity, R.id.hostFragment)
        }
    }

    scope(named<MainNavigationActivity>()) {
        scoped { (activity: MainNavigationActivity) ->
            Navigation
                .findNavController(activity, R.id.hostFragment)
        }
    }
}

val viewModelModule = module {
    viewModel { LoginViewModel(loginRepository = get()) }
}

val repositoryModule = module (override = true) {
    single { LoginRepository() }
}

I'm trying to write a simple unit test for the login function in my LoginRepository . I MockWebServer to moke the response and get the result. here's the code in LoginRepository

LoginRepository

class LoginRepository: KoinComponent {

    val network: APIService by inject()

    var loginMutableData = MutableLiveData<SingleLiveEvent<Resource<UserSession>>>()

    fun getLoginStatus(): LiveData<SingleLiveEvent<Resource<UserSession>>> {
        return loginMutableData
    }

    fun generalLogin(email: String, encryptedPassword: String){

        val login = network.login(email, encryptedPassword)

        login.enqueue(object : Callback<LoginResponse> {

            override fun onResponse(call: Call<LoginResponse>, response: Response<LoginResponse>) {

                if(response.isSuccessful){

                    if(response.body()?.status == 1){
                        val resource = Resource<UserSession>(true,"Success")
                        response.body().let {
                            if(it?.session != null){
                                resource.data = UserSession(it.session.userId!!,it.session.fullName!!)
                            }
                        }

                        loginMutableData.value = SingleLiveEvent(resource)

                    }else{

                        val resource = Resource<UserSession>(false,response.body()?.msg ?: "Login failed. Try again")
                        loginMutableData.value  = SingleLiveEvent(resource)
                    }

                }else{

                    loginMutableData.value = SingleLiveEvent(Resource(false, response.message()))
                }

            }

            override fun onFailure(call: Call<LoginResponse>, t: Throwable) {
                loginMutableData.value = SingleLiveEvent(Resource(false, t.localizedMessage))
            }

        })

    }
}

so I wrote below test class to test this generalLogin(email: String, encryptedPassword: String) function in LoginRepository .

LoginRepositoryTest

class LoginRepositoryTest : KoinTest {

    private val loginRepository: LoginRepository by inject()
    private val server by lazy { MockWebServer() }
    private lateinit var network: APIService

    @get:Rule
    val rule = InstantTaskExecutorRule()

    @Before
    fun setUp() {

        MockitoAnnotations.initMocks(this)

        startKoin {
            printLogger()
            modules(repositoryModule)
        }
    }

    @Test
    fun testLoginWithCorrectCredentials() {

        server.enqueue(
            MockResponse()
                .setResponseCode(200)
                .setBody("{\"msg\":\"success\",\"status\":1,\"session\":{\"userName\":\"Chathuran\",\"loggedin_user_email\":\"valid_email_address@gmail.com\"}}")
        )
        server.start()
        val testingUrl = server.url("account/userAuth/api_login/")

        network = NetworkService.getInstance().getService(APIService::class.java, testingUrl)
        loadKoinModules(module{network})

        val email = "valid_email_address@gmail.com"
        val password = "valid_password"

        loginRepository.generalLogin(email, password)

        loginRepository.getLoginStatus().observeForever {

            it.getContentIfNotHandled()?.also { resource ->
                Assert.assertEquals(email, resource.data?.email)
            }
        }
    }

    @After
    fun tearDown() {
        stopKoin()
        server.shutdown()
    }
}

So in this class, I tried to override the APIService instance with the one I created in test calls. This way I can tell my Retrofit instance to use the base URL provided by MockWebServer . But I'm getting the following error from Koin .

org.koin.core.error.NoBeanDefFoundException: No definition found for 'com.findmyfare.mobile.app.network.APIService' has been found. Check your module definitions.

    at org.koin.core.scope.Scope.findDefinition(Scope.kt:170)
    at org.koin.core.scope.Scope.resolveInstance(Scope.kt:164)
    at org.koin.core.scope.Scope.get(Scope.kt:128)
    at com.findmyfare.mobile.app.repository.LoginRepository$$special$$inlined$inject$1.invoke(Scope.kt:327)
    at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74)
    at com.findmyfare.mobile.app.repository.LoginRepository.getNetwork(LoginRepository.kt)
    at com.findmyfare.mobile.app.repository.LoginRepository.generalLogin(LoginRepository.kt:29)
    at com.findmyfare.mobile.app.repository.LoginRepositoryTest.testLoginWithCorrectCredentials(LoginRepositoryTest.kt:56)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

If this is wrong what is the correct way to override APIService instance? Thanks.

Edit: my build.gradle dependencies

// Koin
    def koin_version = '2.0.1'
    implementation "org.koin:koin-androidx-scope:$koin_version"
    implementation "org.koin:koin-androidx-viewmodel:$koin_version"
    implementation "org.koin:koin-androidx-ext:$koin_version"
    testImplementation "org.koin:koin-test:$koin_version"

//Testing
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    testImplementation 'junit:junit:4.12'
    testImplementation "org.mockito:mockito-core:2.21.0"
    testImplementation 'android.arch.core:core-testing:1.1.1'
    testImplementation 'com.squareup.okhttp3:mockwebserver:4.2.1'
    androidTestImplementation 'androidx.test:runner:1.2.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

Answer 1

You're actually not overriding a bean with your module

network = NetworkService.getInstance().getService(APIService::class.java, testingUrl)
loadKoinModules(module{network})

Instead declare the network bean as an override

network = NetworkService.getInstance().getService(APIService::class.java, testingUrl)
loadKoinModules(module { single(override=true) { network } })

In addition you don't need to use override with your main modules.

With your implementation you don't even need an override with the above. You're not starting the main module with Koin before the test. This might result in another issue, so make sure to have all modules you need running.

startKoin {
    printLogger()
    modules(applicationModule, repositoryModule)
}