Comparing objects using PAssert containsInAnyOrder in Apache Beam

Question

While writing unit tests for my beam pipeline using PAssert, the pipeline outputs objects fine but the test fails during comparison with following assertion error:

java.lang.AssertionError: Decode pubsub message/ParMultiDo(DecodePubSubMessage).output: 
Expected: iterable with items [<PubsubMessage{message=[123, 34, 104...], attributes={messageId=2be485e4-3e53-4468-a482-a49842b87ed5, dataPipelineId=bc957aa3-17e7-46d6-bc73-0924fa5674fa, region=us-west1, ingestionTimestamp=2020-02-02T12:34:56.789Z}, messageId=null}>] in any order
     but: not matched: <PubsubMessage{message=[123, 34, 104...], attributes={messageId=2be485e4-3e53-4468-a482-a49842b87ed5, dataPipelineId=bc957aa3-17e7-46d6-bc73-0924fa5674fa, region=us-west1, ingestionTimestamp=2020-02-02T12:34:56.789Z}, messageId=null}>

I also tried encapsulating expectedOutputPubSubMessage in a list (apparently original output is in an Array) to no avail. All the given PAssert examples in documentation do a simple string or keyvalue comparison.

@RunWith(PowerMockRunner.class)
public class DataDecodePipelineTest implements Serializable {

  @Rule
  public TestPipeline p = TestPipeline.create();

  @Test
  public void testPipeline(){
      PubsubMessage inputPubSubMessage =
              new PubsubMessage(
                      TEST_ENCODED_PAYLOAD.getBytes(),
                      new HashMap<String, String>() {
                          {
                              put(MESSAGE_ID_NAME, TEST_MESSAGE_ID);
                              put(DATA_PIPELINE_ID_NAME, TEST_DATA_PIPELINE_ID);
                              put(INGESTION_TIMESTAMP_NAME, TEST_INGESTION_TIMESTAMP);
                              put(REGION_NAME, TEST_REGION);
                          }
                      });

      PubsubMessage expectedOutputPubSubMessage =
              new PubsubMessage(
                      TEST_DECODED_PAYLOAD.getBytes(),
                      new HashMap<String, String>() {
                          {
                              put(MESSAGE_ID_NAME, TEST_MESSAGE_ID);
                              put(DATA_PIPELINE_ID_NAME, TEST_DATA_PIPELINE_ID);
                              put(INGESTION_TIMESTAMP_NAME, TEST_INGESTION_TIMESTAMP);
                              put(REGION_NAME, TEST_REGION);
                          }
                      });

      PCollection<PubsubMessage> input =
              p.apply(Create.of(Collections.singletonList(inputPubSubMessage)));

      PCollection<PubsubMessage> output =
              input.apply("Decode pubsub message",
                      ParDo.of(new DataDecodePipeline.DecodePubSubMessage()));

      PAssert.that(output).containsInAnyOrder(expectedOutputPubSubMessage);
      
      p.run().waitUntilFinish();
  }
}

Apparently, someone faced the exact same issue years ago which remains unresolved. Test pipeline comparing objects using PAssert containsInAnyOrder()

Are you sure the `equals` method is defined as expected on `PubsubMessage`? — robertwb, Aug 28 '20 at 17:49
No. It's basically the native "this == obj". I am new to java and looked for ways to overriding equals method using 1) Anonymous classes 2) extend PubSubMessage both of which sends me into a blackhole of "Unable to infer a coder and no Coder was specified. Please set a coder by invoking Create.withCoder() explicitly or a schema by invoking Create.withSchema()." I maybe wrong but this use case of comparing two objects for equality in Apache Beam should be pretty common. If anyone can point me in the right direction? — Zain Qasmi, Aug 31 '20 at 08:15
That's unfortunate. You could use wrappers and manually declare the coder as Serializables.of() (Not advised for production use, but fine for tests.) It's worth a FR to allow passing in the comparator, or better passing a list of hamcrest matchers, here. — robertwb, Aug 31 '20 at 17:55

score 0 · Answer 1 · answered Apr 29 '21 at 20:37

The problem is that you are comparing different objects

the return of your pipeline is a PCollection and you are comparing it against PubsubMessage

you have to create a PCollection from the expectedOutputPubSubMessage

Try this:

      PAssert.that(output).containsInAnyOrder(Create.of(Collections.singletonList(expectedOutputPubSubMessage));

example: https://github.com/GoogleCloudPlatform/DataflowTemplates/blob/master/src/test/java/com/google/cloud/teleport/templates/PubsubToPubsubTest.java

Comparing objects using PAssert containsInAnyOrder in Apache Beam

1 Answers1