Component used: WorkManager Testing

Version used: 2.4.0

Devices/Android versions reproduced on: N/A

The documentation has the following example to demonstrate usage of the TestListenableWorkerBuilder extension:

@RunWith(AndroidJUnit4::class)
class SleepWorkerTest {
    private lateinit var context: Context

    @Before
    fun setUp() {
        context = ApplicationProvider.getApplicationContext()
    }

    @Test
    fun testSleepWorker() {
        // Kotlin code can use the TestListenableWorkerBuilder extension to
        // build the ListenableWorker
        val worker = TestListenableWorkerBuilder<SleepWorker>(context).build()
        runBlocking {
            val result = worker.doWork()
            assertThat(result, `is`(Result.success()))
        }
    }
}

If using the Hilt Work integration, this code doesn't work. You need to add the HiltWorkerFactory to the builder. But since the extension function doesn't include the factory in it's parameters, you need to set it afterwards using the Builder's .setWorkerFactory() method. At this point, the reified type parameter is lost, and you have to cast the result of the build() method to your worker type, as in the following modified example:

@HiltAndroidTest
@RunWith(AndroidJUnit4::class)
class SleepWorkerTest {
    
    @get:Rule
    var hiltRule = HiltAndroidRule(this)

    @Inject
    lateinit var workerFactory: HiltWorkerFactory

    @Inject @ApplicationContext
    lateinit var context: Context

    @Before
    fun setUp() {
        hiltRule.inject()
    }

    @Test
    fun testSleepWorker() {
        // Kotlin code can use the TestListenableWorkerBuilder extension to
        // build the ListenableWorker
        val worker = TestListenableWorkerBuilder<SleepWorker>(context)
            .setWorkerFactory(workerFactory)
            .build() as SleepWorker //If you don't do this cast, the doWork() method below won't be found, as the reified type has been lost
        runBlocking {
            val result = worker.doWork()
            assertThat(result, `is`(Result.success()))
        }
    }
}

If we have to do this cast to use the rest of the builder methods not supported by the extension, it defeats the purpose of the extension function's reification.

Thus, please add the ability to set the worker factory to the extension function, so we can get rid of the cast.