Integration tests with WorkManager

WorkManager provides a work-testing artifact which helps with testing of your workers.

Setup

To use the work-testing artifact, add it as an androidTestImplementation dependency in build.gradle.

dependencies {
    def work_version = "2.5.0"

    ...

    // optional - Test helpers
    androidTestImplementation "androidx.work:work-testing:$work_version"
}

dependencies {
    val work_version = "2.4.0"

    ...

    // optional - Test helpers
    androidTestImplementation("androidx.work:work-testing:$work_version")
}

For more information on adding dependencies, look at the Declaring dependencies section in the WorkManager release notes.

Concepts

work-testing provides a special implementation of WorkManager for test mode, which is initialized using WorkManagerTestInitHelper.

The work-testing artifact also provides a SynchronousExecutor which makes it easier to write tests in a synchronous manner, without having to deal with multiple threads, locks, or latches.

Here is an example on how to use all these classes together.

@RunWith(AndroidJUnit4::class)
class BasicInstrumentationTest {
    @Before
    fun setup() {
        val context = InstrumentationRegistry.getTargetContext()
        val config = Configuration.Builder()
            .setMinimumLoggingLevel(Log.DEBUG)
            .setExecutor(SynchronousExecutor())
            .build()

        // Initialize WorkManager for instrumentation tests.
        WorkManagerTestInitHelper.initializeTestWorkManager(context, config)
    }
}

@RunWith(AndroidJUnit4.class)
public class BasicInstrumentationTest {
    @Before
    public void setup() {
        Context context = InstrumentationRegistry.getTargetContext();
        Configuration config = new Configuration.Builder()
                .setMinimumLoggingLevel(Log.DEBUG)
                .setExecutor(new SynchronousExecutor())
                .build();

        // Initialize WorkManager for instrumentation tests.
        WorkManagerTestInitHelper.initializeTestWorkManager(
            context, config);
    }
}

Structuring Tests

Now that WorkManager has been initialized in test mode, you are ready to test your workers.

Let’s say you have an EchoWorker which expects some inputData, and simply copies (echoes) its input to outputData.

class EchoWorker(context: Context, parameters: WorkerParameters)
   : Worker(context, parameters) {
   override fun doWork(): Result {
       return when(inputData.size()) {
           0 -> Result.failure()
           else -> Result.success(inputData)
       }
   }
}

public class EchoWorker extends Worker {
  public EchoWorker(Context context, WorkerParameters parameters) {
      super(context, parameters);
  }

  @NonNull
  @Override
  public Result doWork() {
      Data input = getInputData();
      if (input.size() == 0) {
          return Result.failure();
      } else {
          return Result.success(input);
      }
  }
}

Basic Tests

Below is an Android Instrumentation test that tests EchoWorker. The main takeaway here is that testing EchoWorker in test mode is very similar to how you would use EchoWorker in a real application.

@Test
@Throws(Exception::class)
fun testSimpleEchoWorker() {
    // Define input data
    val input = workDataOf(KEY_1 to 1, KEY_2 to 2)

    // Create request
    val request = OneTimeWorkRequestBuilder<EchoWorker>()
        .setInputData(input)
        .build()

    val workManager = WorkManager.getInstance(applicationContext)
    // Enqueue and wait for result. This also runs the Worker synchronously
    // because we are using a SynchronousExecutor.
    workManager.enqueue(request).result.get()
    // Get WorkInfo and outputData
    val workInfo = workManager.getWorkInfoById(request.id).get()
    val outputData = workInfo.outputData

    // Assert
    assertThat(workInfo.state, `is`(WorkInfo.State.SUCCEEDED))
    assertThat(outputData, `is`(input))
}

@Test
public void testSimpleEchoWorker() throws Exception {
   // Define input data
   Data input = new Data.Builder()
           .put(KEY_1, 1)
           .put(KEY_2, 2)
           .build();

   // Create request
   OneTimeWorkRequest request =
       new OneTimeWorkRequest.Builder(EchoWorker.class)
           .setInputData(input)
           .build();

   WorkManager workManager = WorkManager.getInstance(getApplicationContext());
   // Enqueue and wait for result. This also runs the Worker synchronously
   // because we are using a SynchronousExecutor.
   workManager.enqueue(request).getResult().get();
   // Get WorkInfo and outputData
   WorkInfo workInfo = workManager.getWorkInfoById(request.getId()).get();
   Data outputData = workInfo.getOutputData();

   // Assert
   assertThat(workInfo.getState(), is(WorkInfo.State.SUCCEEDED));
   assertThat(outputData, is(input));
}

Let’s write another test which makes sure that when EchoWorker gets no input data, the expected Result is a Result.failure().

@Test
@Throws(Exception::class)
fun testEchoWorkerNoInput() {
   // Create request
   val request = OneTimeWorkRequestBuilder<EchoWorker>()
       .build()

   val workManager = WorkManager.getInstance(applicationContext)
   // Enqueue and wait for result. This also runs the Worker synchronously
   // because we are using a SynchronousExecutor.
   workManager.enqueue(request).result.get()
   // Get WorkInfo
   val workInfo = workManager.getWorkInfoById(request.id).get()

   // Assert
   assertThat(workInfo.state, `is`(WorkInfo.State.FAILED))
}

@Test
public void testEchoWorkerNoInput() throws Exception {
  // Create request
  OneTimeWorkRequest request =
      new OneTimeWorkRequest.Builder(EchoWorker.class)
         .build();

  WorkManager workManager = WorkManager.getInstance(getApplicationContext());
  // Enqueue and wait for result. This also runs the Worker synchronously
  // because we are using a SynchronousExecutor.
  workManager.enqueue(request).getResult().get();
  // Get WorkInfo
  WorkInfo workInfo = workManager.getWorkInfoById(request.getId()).get();

  // Assert
  assertThat(workInfo.getState(), is(WorkInfo.State.FAILED));
}

Simulate constraints, delays, and periodic work

WorkManagerTestInitHelper provides you with an instance of TestDriver which can be used to simulate initial delay, conditions where constraints are met for ListenableWorker instances, and, intervals for PeriodicWorkRequest instances.

Test Initial Delays

Workers can have initial delays. To test EchoWorker with an initialDelay, rather than having to wait for the initialDelay in your test, you can use the TestDriver to mark the work request’s initial delay as met using setInitialDelayMet.

@Test
@Throws(Exception::class)
fun testWithInitialDelay() {
    // Define input data
    val input = workDataOf(KEY_1 to 1, KEY_2 to 2)

    // Create request
    val request = OneTimeWorkRequestBuilder<EchoWorker>()
        .setInputData(input)
        .setInitialDelay(10, TimeUnit.SECONDS)
        .build()

    val workManager = WorkManager.getInstance(getApplicationContext())
    // Get the TestDriver
    val testDriver = WorkManagerTestInitHelper.getTestDriver()
    // Enqueue
    workManager.enqueue(request).result.get()
    // Tells the WorkManager test framework that initial delays are now met.
    testDriver.setInitialDelayMet(request.id)
    // Get WorkInfo and outputData
    val workInfo = workManager.getWorkInfoById(request.id).get()
    val outputData = workInfo.outputData

    // Assert
    assertThat(workInfo.state, `is`(WorkInfo.State.SUCCEEDED))
    assertThat(outputData, `is`(input))
}

@Test
public void testWithInitialDelay() throws Exception {
  // Define input data
  Data input = new Data.Builder()
          .put(KEY_1, 1)
          .put(KEY_2, 2)
          .build();

  // Create request
  OneTimeWorkRequest request = new OneTimeWorkRequest.Builder(EchoWorker.class)
          .setInputData(input)
          .setInitialDelay(10, TimeUnit.SECONDS)
          .build();

  WorkManager workManager = WorkManager.getInstance(myContext);
  // Get the TestDriver
  TestDriver testDriver = WorkManagerTestInitHelper.getTestDriver();
  // Enqueue
  workManager.enqueue(request).getResult().get();
  // Tells the WorkManager test framework that initial delays are now met.
  testDriver.setInitialDelayMet(request.getId());
  // Get WorkInfo and outputData
  WorkInfo workInfo = workManager.getWorkInfoById(request.getId()).get();
  Data outputData = workInfo.getOutputData();

  // Assert
  assertThat(workInfo.getState(), is(WorkInfo.State.SUCCEEDED));
  assertThat(outputData, is(input));
}

Testing Constraints

TestDriver can also be used to mark constraints as met using setAllConstraintsMet. Here is an example on how you can test a Worker with constraints.

@Test
@Throws(Exception::class)
fun testWithConstraints() {
    // Define input data
    val input = workDataOf(KEY_1 to 1, KEY_2 to 2)

    val constraints = Constraints.Builder()
        .setRequiredNetworkType(NetworkType.CONNECTED)
        .build()

    // Create request
    val request = OneTimeWorkRequestBuilder<EchoWorker>()
        .setInputData(input)
        .setConstraints(constraints)
        .build()

    val workManager = WorkManager.getInstance(myContext)
    val testDriver = WorkManagerTestInitHelper.getTestDriver()
    // Enqueue
    workManager.enqueue(request).result.get()
    // Tells the testing framework that all constraints are met.
    testDriver.setAllConstraintsMet(request.id)
    // Get WorkInfo and outputData
    val workInfo = workManager.getWorkInfoById(request.id).get()
    val outputData = workInfo.outputData

    // Assert
    assertThat(workInfo.state, `is`(WorkInfo.State.SUCCEEDED))
    assertThat(outputData, `is`(input))
}

@Test
public void testWithConstraints() throws Exception {
    // Define input data
    Data input = new Data.Builder()
            .put(KEY_1, 1)
            .put(KEY_2, 2)
            .build();

    // Define constraints
    Constraints constraints = new Constraints.Builder()
            .setRequiresDeviceIdle(true)
            .build();

    // Create request
    OneTimeWorkRequest request = new OneTimeWorkRequest.Builder(EchoWorker.class)
            .setInputData(input)
            .setConstraints(constraints)
            .build();

    WorkManager workManager = WorkManager.getInstance(myContext);
    TestDriver testDriver = WorkManagerTestInitHelper.getTestDriver();
    // Enqueue
    workManager.enqueue(request).getResult().get();
    // Tells the testing framework that all constraints are met.
    testDriver.setAllConstraintsMet(request.getId());
    // Get WorkInfo and outputData
    WorkInfo workInfo = workManager.getWorkInfoById(request.getId()).get();
    Data outputData = workInfo.getOutputData();

    // Assert
    assertThat(workInfo.getState(), is(WorkInfo.State.SUCCEEDED));
    assertThat(outputData, is(input));
}

Testing Periodic Work

The TestDriver also exposes a setPeriodDelayMet which can be used to indicate that an interval is complete. Here is an example of setPeriodDelayMet being used.

@Test
@Throws(Exception::class)
fun testPeriodicWork() {
    // Define input data
    val input = workDataOf(KEY_1 to 1, KEY_2 to 2)

    // Create request
    val request = PeriodicWorkRequestBuilder<EchoWorker>(15, MINUTES)
        .setInputData(input)
        .build()

    val workManager = WorkManager.getInstance(myContext)
    val testDriver = WorkManagerTestInitHelper.getTestDriver()
    // Enqueue and wait for result.
    workManager.enqueue(request).result.get()
    // Tells the testing framework the period delay is met
    testDriver.setPeriodDelayMet(request.id)
    // Get WorkInfo and outputData
    val workInfo = workManager.getWorkInfoById(request.id).get()

    // Assert
    assertThat(workInfo.state, `is`(WorkInfo.State.ENQUEUED))
}

@Test
public void testPeriodicWork() throws Exception {
    // Define input data
    Data input = new Data.Builder()
            .put(KEY_1, 1)
            .put(KEY_2, 2)
            .build();

    // Create request
    PeriodicWorkRequest request =
            new PeriodicWorkRequest.Builder(EchoWorker.class, 15, MINUTES)
            .setInputData(input)
            .build();

    WorkManager workManager = WorkManager.getInstance(myContext);
    TestDriver testDriver = WorkManagerTestInitHelper.getTestDriver();
    // Enqueue and wait for result.
    workManager.enqueue(request).getResult().get();
    // Tells the testing framework the period delay is met
    testDriver.setPeriodDelayMet(request.getId());
    // Get WorkInfo and outputData
    WorkInfo workInfo = workManager.getWorkInfoById(request.getId()).get();

    // Assert
    assertThat(workInfo.getState(), is(WorkInfo.State.ENQUEUED));
}