I've using Kotest recently and I hadn't had any issues, but recently I was trying some annotations for dependency injection so to simplify the problem I created some basic classes with some methods that just print some messages, just for the sake of learning how to use Kotest and Mockk, but during the testing, I ran with the exception that the variable hasn't been initialized when trying to run the test.
These are my classes
class DefaultClass : AbstractClass() {
private val anotherClass: AnotherClass = AnotherClass()
fun testMethod(value: String): String {
val normalizeValue = value.trim().lowercase().replace(Regex("[^ A-Za-z\\d]*"), "")
return runBlocking {
anotherClass.someOtherMethod()
callsProtectedMethod(normalizeValue)
}
}
private suspend fun callsProtectedMethod(value: String) = coroutineScope {
println("Original method")
returnDefaultString(value)
}
}
AnotherClass
class AnotherClass {
fun someOtherMethod(): Unit {
println("SomeOtherMethod original")
}
}
Test
class DefaultClassTest : FunSpec({
context("Testing DefaultClass") {
#MockK
lateinit var anotherClass: AnotherClass
#OverrideMockKs
lateinit var defaultClass: DefaultClass
beforeContainer {
MockKAnnotations.init(this)
}
test("testing mocks") {
defaultClass.testMethod("some method")
}
}
I've changed the initialization to beforeTest, taken it out of the context, and also use beforeContainer, beforeTest, beforeSpec, but none of these work... every time I still get lateinit property defaultClass has not been initialized
So, I recreated the same test using JUnit and I don't have this issue.
class DefaultClassJUnitTest {
companion object {
#MockK
lateinit var anotherClass: AnotherClass
#OverrideMockKs
lateinit var defaultClass: DefaultClass
#BeforeAll
#JvmStatic
fun setup() {
MockKAnnotations.init(this)
}
}
#Test
fun `Testing with JUnit`() {
every { anotherClass.someOtherMethod() } answers {
println("Mocking another class")
}
val value = defaultClass.testMethod("some method")
}
}
So I'm pretty sure that I'm doing something wrong when using Kotest. I hope anyone might help me, thanks...
I think MockK is probably not looking for variables defined within function scopes. If you want to use the annotations, you likely have to move them to the companion object, like this:
class DefaultClassTest : FunSpec({
context("Testing DefaultClass") {
beforeContainer {
MockKAnnotations.init(this)
}
test("testing mocks") {
defaultClass.testMethod("some method")
}
}
}) {
companion object {
#MockK
lateinit var anotherClass: AnotherClass
#OverrideMockKs
lateinit var defaultClass: DefaultClass
}
}
Related
I've read that static methods cannot overridden in Kotlin, so I'm not sure if this is possible, but not being able to do so would result in a lot of repetitious code. Is there any way to achieve the same behavior while moving the companion object into the Parent? Here is what I have so far
Parent.kt
abstract class Parent {
protected val TAG = this::class.java.simpleName
}
Brother.kt
class Brother: Parent() {
companion object {
#Volatile private var instance: Brother? = null
fun getInstance() = instance ?: synchronized(this) {
instance ?: Brother().also { instance = it }
}
}
}
Sister.kt
class Sister: Parent() {
companion object {
#Volatile private var instance: Sister? = null
fun getInstance() = instance ?: synchronized(this) {
instance ?: Sister().also { instance = it }
}
}
}
main()
fun main() {
println("Hello, ${Brother.getInstance().TAG}")
println("Hello, ${Sister.getInstance().TAG}")
}
Console Output:
Hello, Brother Hello, Sister
Maybe this will work for what you're trying to do.
You can create a superclass for objects that do this pattern:
open class SingletonAccessor<T: Any> (private val constructor: () -> T){
#Volatile private var instance: T? = null
fun getInstance() = instance ?: synchronized(this) {
instance ?: constructor().also { instance = it }
}
}
And then inherit it from your implementation class companion objects:
class Brother private constructor(): Parent() {
companion object: SingletonAccessor<Brother>(::Brother)
}
class Sister private constructor(): Parent() {
companion object: SingletonAccessor<Sister>(::Sister)
}
This pattern isn't much different from simply making Brother and Sister objects, since they have no constructor parameters, but maybe this is just a simplified example.
Based on #Tenfour04's answer, I've come up with an alternate approach, which incorporates the SingletonAccessor into the Parent
abstract class Parent<T>(private val constructor: () -> T) {
#Volatile private var instance: T? = null
protected val TAG = this::class.java.simpleName
fun getInstance() = instance ?: synchronized(this) {
instance ?: constructor().also { instance = it }
}
}
The implementation in the children is the same as before.
Let me know if this answer can be improved further. In particular, I would like to do in the class declaration class Parent<T: Parent>, but that doesn't compile. Is there a way to limit the type parameter to itself and its children?
class ModelFactory {
fun setA() : ModelFactory {
// blabla...
}
fun setB() : ModelFactory {
// blabla...
}
fun setC() : ModelFactory {
// blabla...
}
fun build() : Model {
// An error occurs if any of setA, setB, and setC is not called.
}
}
//example
fun successTest() {
ModelFactory().setA().setB().setC().build() // No error occurs at compile time
}
fun failTest() {
ModelFactory().setA().build() // An error occurs at compile time because setB and setC are not called.
}
It's awkward grammatically, but I think it's been expressed what I want.
I have already implemented an error-raising runtime for this requirement, but I want to check this at compile time.
If possible, I think I should use annotations. But is this really possible at compile time?
With Kotlin, I have been avoiding builder pattern, as we can always specify default values for non-mandatory fields.
If you still want to use a builder pattern, you can use Step builder pattern that expects all mandatory fields to be set before creating the object. Note that each setter method returns the reference of next setter interface. You can have multiple Step builders based on the combination of mandatory fields.
class Model(val a: String = "", val b: String = "", val c: String = "")
class StepBuilder {
companion object {
fun builder(): AStep = Steps()
}
interface AStep {
fun setA(a: String): BStep
}
interface BStep {
fun setB(b: String): CStep
}
interface CStep {
fun setC(c: String): BuildStep
}
interface BuildStep {
//fun setOptionalField(x: String): BuildStep
fun build(): Model
}
class Steps : AStep, BStep, CStep, BuildStep {
private lateinit var a: String
private lateinit var b: String
private lateinit var c: String
override fun setA(a: String): BStep {
this.a = a
return this
}
override fun setB(b: String): CStep {
this.b = b
return this
}
override fun setC(c: String): BuildStep {
this.c = c
return this
}
override fun build() = Model(a, b , c)
}
}
fun main() {
// cannot build until you call all three setters
val model = StepBuilder.builder().setA("A").setB("B").setC("C").build()
}
Error with Kotlin conversion from java, this project is testing Github Api and displaying data in recyclerview.I get the a compile error which i cannot workout for Dagger2, it worked in Java but when converting to Kotlin i get a compile error at runtime.
It seems to be with injecting an api method into the view model
i have tried following the error then cleaning and rebuilding the app
I have also tried invalidating caches and restarting but seems there is an error with the conversion into Kotlin from Java. Any help would be appreciated.
Here is my class:
class RepoRepository {
private lateinit var repoService: GithubRepos
#Inject
fun RepoRepository(repoService: GithubRepos) {
this.repoService = repoService
}
fun getRepositories(): Single<List<Repo>> {
return repoService.getRepos()
}
fun getSingleRepo(owner: String, name: String): Single<Repo> {
return repoService.getSingleRepo(owner, name)
}
}
My component class:
#Singleton
#Component(modules = arrayOf(NetworkModule::class))
interface AppComponent {
/**
* inject required dependencies into MainActivityListViewModel
*/
fun inject(mainActivityListViewModel: MainActivityListViewModel)
#Component.Builder
interface Builder {
fun build(): AppComponent
fun networkModule(networkModule: NetworkModule): Builder
}
}
And my ViewModel:
class MainActivityListViewModel : BaseViewModel() {
private lateinit var repoRepository: RepoRepository
private var disposable: CompositeDisposable? = null
private val repos = MutableLiveData<List<Repo>>()
private val repoLoadError = MutableLiveData<Boolean>()
private val loading = MutableLiveData<Boolean>()
#Inject
fun ListViewModel(repoRepository: RepoRepository) {
this.repoRepository = repoRepository
disposable = CompositeDisposable()
fetchRepos()
}
fun getRepos(): LiveData<List<Repo>> {
return repos
}
fun getError(): LiveData<Boolean> {
return repoLoadError
}
fun getLoading(): LiveData<Boolean> {
return loading
}
private fun fetchRepos() {
loading.value = true
disposable?.add(repoRepository.getRepositories()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribeWith(object :
DisposableSingleObserver<List<Repo>>() {
override fun onSuccess(value: List<Repo>) {
repoLoadError.value = false
repos.value = value
loading.value = false
}
override fun onError(e: Throwable) {
repoLoadError.value = true
loading.value = false
}
}))
}
override fun onCleared() {
super.onCleared()
if (disposable != null) {
disposable!!.clear()
disposable = null
}
}
}
this is error i am getting:
[Dagger/MissingBinding] repos.network.RepoRepository cannot be
provided without an #Inject constructor or an #Provides-annotated
method. This type supports members injection but cannot be
implicitly provided.
public abstract repos.network.RepoRepository
repoRepository();
^
repos.network.RepoRepository is provided at
components.AppComponent.repoRepository() e: repos/di/components/AppComponent.java:19: error:
[Dagger/MissingBinding] repos.network.RepoRepository cannot be
provided without an #Inject constructor or an #Provides- annotated
method. This type supports members injection but cannot be
implicitly provided.
^
repos.network.RepoRepository is injected at
repos.viewmodels.MainActivityListViewModel.ListViewModel(repoRepository)
repos.viewmodels.MainActivityListViewModel is injected at
repos.di.components.AppComponent.inject(repos.viewmodels.MainActivityListViewModel)
Your error clearly says:
[Dagger/MissingBinding] repos.network.RepoRepository cannot be provided without an #Inject constructor or an #Provides-annotated method.
You didn't define constructor for your RepoRepository class.
It should look something like this:
class RepoRepository #Inject constructor(private val repoService: GithubRepos) {//the rest of your code here}
This goes for your viewmodel class as well.
If you are using android ViewModel architecture component i suggest you read this article which explains how to use it with Dagger2.
Hope this helps.
I'm trying to inject LatestChart in AppComponent and sloving issue with [Dagger/MissingBinding] LatestChart cannot be provided without an #Inject constructor or an #Provides-annotated method...
Thanks in advance for your help
LatestChart.kt
class LatestChart {
#Inject
lateinit var context: Context
#Inject
lateinit var formatter: YearValueFormatter
lateinit var chart: LineChart
init {
App.appComponent.inject(this)
}
fun initChart(chart: LineChart) {
this.chart = chart
***
}
fun addEntry(value: Float, date: Float) {
***
}
}
private fun createSet(): LineDataSet {
***
}
return set
}
}
And AppComponent.kt
#Component(modules = arrayOf(AppModule::class, RestModule::class, MvpModule::class, ChartModule::class))
#Singleton
interface AppComponent {
***
fun inject(chart: LatestChart)
}
Compilation error:
***AppComponent.java:8: error: [Dagger/MissingBinding] sn0w.test.crypto.chart.LatestChart cannot be provided without an #Inject constructor or an #Provides-annotated method. This type supports members injection but cannot be implicitly provided.
public abstract interface AppComponent {
^
A binding with matching key exists in component: sn0w.test.crypto.di.AppComponent
sn0w.test.crypto.chart.LatestChart is injected at
sn0w.test.crypto.activities.ChartActivity.latestChart
sn0w.test.crypto.activities.ChartActivity is injected at
sn0w.test.crypto.di.AppComponent.inject(sn0w.test.crypto.activities.ChartActivity)
The way you are currently trying to inject dependencies into the LatestChart is how you satisfy the dependencies in objects that won't be created by Dagger (e.g. activities). If you create the LatestChart object by yourself (just val latestCharts = LatestCharts()), you'll see that context and formatter are actually injected into this newly created instance.
However if you want Dagger to inject a LatestChart object into another (into ChartActivity I assume based on the compilation error), you have to let Dagger know how to create its instances. There are 2 ways to achieve that:
1. Annotate the LatestChart constructor with #Inject
class LatestChart #Inject constructor(
private val context: Context,
private val formatter: YearValueFormatter
) {
lateinit var chart: LineChart
fun initChart(chart: LineChart) { ... }
fun addEntry(value: Float, date: Float) { ... }
private fun createSet(): LineDataSet { ... }
}
2. Create a provider method in one of Dagger modules
class LatestChart(private val context: Context, private val formatter: YearValueFormatter) {
lateinit var chart: LineChart
fun initChart(chart: LineChart) { ... }
fun addEntry(value: Float, date: Float) { ... }
private fun createSet(): LineDataSet { ... }
}
#Module
class LatestChartModule {
#Module
companion object {
#JvmStatic
#Provides
fun provideLatestChart(context: Context, formatter: YearValueFormatter): LatestChart =
LatestChart(context, formatter)
}
}
I am new to Guice. I am trying to use requestInjection to inject the dependencies of a kotlin singleton object in this way.
APPROACH 1:
class SampleTest {
#Test
fun test() {
Guice.createInjector(object: KotlinModule() {
override fun configure() {
requestInjection(A)
}
})
assertEquals("Hello world", A.saySomething())
}
}
object A {
#Inject
private lateinit var b: B
fun saySomething(): String {
return b.sayHello()
}
}
class B {
fun sayHello(): String {
return "Hello world"
}
}
But I am getting this error:
kotlin.UninitializedPropertyAccessException: lateinit property b has not been initialized
If I change A to a class with no-arg constructor, it works.
APPROACH 2:
class SampleTest {
#Test
fun test() {
val a = A()
Guice.createInjector(object: KotlinModule() {
override fun configure() {
requestInjection(a)
}
})
assertEquals("Hello world", a.saySomething())
}
}
class A {
#Inject
private lateinit var b: B
fun saySomething(): String {
return b.sayHello()
}
}
class B {
fun sayHello(): String {
return "Hello world"
}
}
Instead, if I change requestInjection to requestStaticInjection, it also works.
APPROACH 3:
class SampleTest {
#Test
fun test() {
Guice.createInjector(object: KotlinModule() {
override fun configure() {
requestStaticInjection<A>()
}
})
assertEquals("Hello world", A.saySomething())
}
}
object A {
#Inject
private lateinit var b: B
fun saySomething(): String {
return b.sayHello()
}
}
class B {
fun sayHello(): String {
return "Hello world"
}
}
Why didn't APPROACH 1 work? Why did APPROACH 2 and APPROACH 3 work?
Kotlin's objects are treated as language static singletons, i.e. their initialization/instantiations happens outside the scope of the dependency injection framework.
Therefor, when using the KotlinModule to inject an object, you have to use requestStaticInjection like in APPROACH 3, or change that object to a class, so that the Guice KotlinModule sees it as non-static, as presented in APPROACH 2
Hope that clarifies things a bit.