simplified_test_with_di.kt

class InMemoryBlockingCacheTest {
  @ExperimentalCoroutinesApi
  @Inject
  @field:TestDispatcher
  lateinit var testDispatcher: TestCoroutineDispatcher

  @ExperimentalCoroutinesApi
  private val backgroundTestCoroutineScope by lazy {
    CoroutineScope(backgroundTestCoroutineDispatcher)
  }

  @ExperimentalCoroutinesApi
  private val backgroundTestCoroutineDispatcher by lazy {
    TestCoroutineDispatcher()
  }

  @Before
  @ExperimentalCoroutinesApi
  fun setUp() {
    setUpTestApplicationComponent()
  }

  @Test
  @ExperimentalCoroutinesApi
  fun testReadCache_withoutInitialValue_providesNull() = runBlockingTest(testDispatcher) {
    // Test with testDispatcher since it's connected to the blocking dispatcher.
  }

  private fun setUpTestApplicationComponent() {
    DaggerInMemoryBlockingCacheTest_TestApplicationComponent.builder()
      .setApplication(ApplicationProvider.getApplicationContext())
      .build()
      .inject(this)
  }

  @Qualifier annotation class TestDispatcher

  @Module
  class TestModule {
    @ExperimentalCoroutinesApi
    @Singleton
    @Provides
    @TestDispatcher
    fun provideTestDispatcher(): TestCoroutineDispatcher {
      return TestCoroutineDispatcher()
    }

    @ExperimentalCoroutinesApi
    @Singleton
    @Provides
    @BlockingDispatcher
    fun provideBlockingDispatcher(@TestDispatcher testDispatcher: TestCoroutineDispatcher): CoroutineDispatcher {
      return testDispatcher
    }
  }

  @Singleton
  @Component(modules = [TestModule::class])
  interface TestApplicationComponent {
    @Component.Builder
    interface Builder {
      @BindsInstance
      fun setApplication(application: Application): Builder
      fun build(): TestApplicationComponent
    }

    fun inject(inMemoryBlockingCacheTest: InMemoryBlockingCacheTest)
  }
}