Step4. Use Dagger

- Updated Dagger version due to bug[google/dagger#3032]

app/build.gradle

@@ -41,8 +41,14 @@ dependencies {
     implementation "io.reactivex.rxjava2:rxandroid:2.1.1"
 
     // Dagger2
-    implementation "com.google.dagger:dagger:2.38.1"
-    kapt "com.google.dagger:dagger-compiler:2.38.1"
+    implementation "com.google.dagger:dagger:2.44.2"
+    implementation 'io.mockk:mockk-android:1.13.3'
+    testImplementation 'junit:junit:4.12'
+    kapt "com.google.dagger:dagger-compiler:2.44.2"
+    implementation "com.google.dagger:dagger-android:2.44.2"
+    kapt "com.google.dagger:dagger-android-processor:2.44.2"
+    implementation "com.google.dagger:dagger-android-support:2.44.2"
+    kapt "com.google.dagger:dagger-android-support:2.44.2"
 
     // Retrofit
     implementation "com.squareup.retrofit2:retrofit:2.9.0"
@@ -58,4 +64,7 @@ dependencies {
     testImplementation 'junit:junit:4.13.2'
     androidTestImplementation 'androidx.test.ext:junit:1.1.3'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
+    testImplementation "androidx.test.ext:junit-ktx:1.1.3"
+    testImplementation "androidx.test:core-ktx:1.4.0"
+    testImplementation "org.robolectric:robolectric:4.4"
 }

app/src/main/java/com/buzzvil/onboarding/MyApplication.kt

@@ -1,11 +1,15 @@
 package com.buzzvil.onboarding
 
 import android.app.Application
+import com.buzzvil.onboarding.di.AppComponent
+import com.buzzvil.onboarding.di.DaggerAppComponent
 
 class MyApplication : Application() {
-    lateinit var container: Container
+    var appComponent: AppComponent? = null
     override fun onCreate() {
         super.onCreate()
-        container = Container()
+        appComponent = DaggerAppComponent.builder()
+            .appContext(this)
+            .build()
     }
 }

app/src/main/java/com/buzzvil/onboarding/data/AdRepositoryImpl.kt

@@ -2,13 +2,10 @@ package com.buzzvil.onboarding.data
 
 import com.buzzvil.onboarding.domain.model.Ad
 import com.buzzvil.onboarding.domain.repository.AdRepository
-import com.google.gson.Gson
 import io.reactivex.Single
-import retrofit2.Retrofit
-import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory
-import retrofit2.converter.gson.GsonConverterFactory
+import javax.inject.Inject
 
-class AdRepositoryImpl(private val buzzAdApi: BuzzAdApi) : AdRepository {
+class AdRepositoryImpl @Inject constructor(private val buzzAdApi: BuzzAdApi) : AdRepository {
     override fun fetchAd(): Single<Ad> {
         return buzzAdApi.get()
     }

app/src/main/java/com/buzzvil/onboarding/di/AppComponent.kt

@@ -0,0 +1,21 @@
+package com.buzzvil.onboarding.di
+
+import android.content.Context
+import com.buzzvil.onboarding.presentation.MainActivity
+import dagger.BindsInstance
+import dagger.Component
+
+@Component(modules = [
+    NetworkModule::class
+])
+interface AppComponent {
+    fun inject(mainActivity: MainActivity)
+
+    @Component.Builder
+    interface Builder {
+        fun build(): AppComponent
+
+        @BindsInstance
+        fun appContext(context: Context): Builder
+    }
+}

app/src/main/java/com/buzzvil/onboarding/di/NetworkModule.kt

@@ -0,0 +1,36 @@
+package com.buzzvil.onboarding.di
+
+import com.buzzvil.onboarding.data.AdRepositoryImpl
+import com.buzzvil.onboarding.data.BuzzAdApi
+import com.buzzvil.onboarding.domain.repository.AdRepository
+import com.google.gson.Gson
+import dagger.Binds
+import dagger.Module
+import dagger.Provides
+import retrofit2.Retrofit
+import retrofit2.adapter.rxjava2.RxJava2CallAdapterFactory
+import retrofit2.converter.gson.GsonConverterFactory
+
+@Module
+abstract class NetworkModule {
+    @Binds
+    abstract fun bindsAdRepository(repositoryImpl: AdRepositoryImpl): AdRepository
+
+    companion object {
+        @Provides
+        fun providesGson(): Gson = Gson().newBuilder()
+            .setLenient()
+            .create()
+
+        @Provides
+        fun providesRetrofit(gson: Gson): Retrofit = Retrofit.Builder()
+            .baseUrl("https://s3-ap-northeast-1.amazonaws.com/buzzvi.test/")
+            .addConverterFactory(GsonConverterFactory.create(gson))
+            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
+            .build()
+
+        @Provides
+        fun providesBuzzAdApi(retrofit: Retrofit): BuzzAdApi =
+            retrofit.create(BuzzAdApi::class.java)
+    }
+}

app/src/main/java/com/buzzvil/onboarding/domain/usecase/FetchAd.kt

@@ -3,8 +3,9 @@ package com.buzzvil.onboarding.domain.usecase
 import com.buzzvil.onboarding.domain.model.Ad
 import com.buzzvil.onboarding.domain.repository.AdRepository
 import io.reactivex.Single
+import javax.inject.Inject
 
-class FetchAd (private val adRepository: AdRepository) {
+class FetchAd @Inject constructor(private val adRepository: AdRepository) {
     operator fun invoke(): Single<Ad> {
         return adRepository.fetchAd()
     }

app/src/main/java/com/buzzvil/onboarding/presentation/MainActivity.kt

@@ -2,36 +2,34 @@ package com.buzzvil.onboarding.presentation
 
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
-import com.buzzvil.onboarding.Container
 import com.buzzvil.onboarding.MyApplication
 import com.buzzvil.onboarding.databinding.ActivityMainBinding
+import com.buzzvil.onboarding.domain.repository.AdRepository
 import com.buzzvil.onboarding.domain.usecase.FetchAd
-import io.reactivex.android.schedulers.AndroidSchedulers
-import io.reactivex.disposables.CompositeDisposable
-import io.reactivex.schedulers.Schedulers
+import javax.inject.Inject
 
 class MainActivity : AppCompatActivity() {
     companion object {
         const val TAG = "MAIN_ACTIVITY"
     }
 
-    private lateinit var viewModel: MainViewModel
-    private lateinit var fetchAd: FetchAd
+    @Inject
+    lateinit var viewModel: MainViewModel
     private lateinit var binding: ActivityMainBinding
 
     override fun onCreate(savedInstanceState: Bundle?) {
+        (applicationContext as MyApplication).appComponent?.inject(this)
+
         super.onCreate(savedInstanceState)
         binding = ActivityMainBinding.inflate(layoutInflater)
         setContentView(binding.root)
 
-        inject((application as MyApplication).container)
-        viewModel = MainViewModel(fetchAd)
         observeViewState()
     }
 
     override fun onResume() {
         super.onResume()
-        loadViewState()
+//        loadViewState() // NOTE: 필요한 경우 (Ex. Resume이 되었을 때, update가 필요한 경우에만 사용)
     }
 
     private fun loadViewState() {
@@ -51,8 +49,4 @@ class MainActivity : AppCompatActivity() {
     private fun handleViewState(viewState: MainViewModel.ViewState) {
         binding.textView.text = viewState.text
     }
-
-    private fun inject(container: Container) {
-        fetchAd = container.fetchAd
-    }
 }

app/src/main/java/com/buzzvil/onboarding/presentation/MainViewModel.kt

@@ -7,8 +7,9 @@ import com.buzzvil.onboarding.domain.usecase.FetchAd
 import io.reactivex.android.schedulers.AndroidSchedulers
 import io.reactivex.disposables.CompositeDisposable
 import io.reactivex.schedulers.Schedulers
+import javax.inject.Inject
 
-class MainViewModel(private val fetchAd: FetchAd) : ViewModel() {
+class MainViewModel @Inject constructor(private val fetchAd: FetchAd) : ViewModel() {
     data class ViewState(val text: String = "")
 
     private val compositeDisposable = CompositeDisposable()

app/src/test/java/com/buzzvil/onboarding/presentation/MainViewModelTest.kt

@@ -0,0 +1,34 @@
+package com.buzzvil.onboarding.presentation
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.buzzvil.onboarding.domain.model.Ad
+import com.buzzvil.onboarding.domain.usecase.FetchAd
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.verify
+import io.reactivex.Single
+import org.junit.Assert.*
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class MainViewModelTest {
+    private lateinit var fetchAd: FetchAd
+    private lateinit var mainViewModel: MainViewModel
+
+    @Before
+    fun setUp() {
+        fetchAd = mockk()
+    }
+
+    @Test
+    fun `test 111`() {
+        every {
+            fetchAd()
+        } returns Single.just(Ad(listOf()))
+        mainViewModel = MainViewModel(fetchAd)
+
+        verify { fetchAd() }
+    }
+}