apache/beam · error · IllegalArgumentException

Both PubsubTestClientFactory and Clock need to be specified…

Error message

Both PubsubTestClientFactory and Clock need to be specified for testing, but only one is provided

What it means

In buildPubsubRead, test hooks (a PubsubTestClientFactory and a Clock) must be supplied as a pair. If exactly one of clientFactory or clock is set on the provider, it throws, because the test client cannot operate correctly with only one of the two.

Solutions

Set BOTH clientFactory and clock on the provider when testing.
If not testing against a fake Pubsub client, clear BOTH fields so the production client path is used.
Review test setup helpers to ensure the pair is always set together.

Example fix

// before
provider = new PubsubReadSchemaTransformProvider().withClientFactory(factory); // clock missing
// after
provider = new PubsubReadSchemaTransformProvider().withClientFactory(factory).withClock(clock);

Defensive patterns

Strategy: validation

Validate before calling

if ((provider.clientFactory != null) != (provider.clock != null)) { throw new IllegalStateException("Set both PubsubTestClientFactory and Clock for testing, or neither"); }

Try / catch

try { return provider.from(cfg); } catch (IllegalArgumentException e) { if (e.getMessage().contains("PubsubTestClientFactory")) { /* complete the test pair */ } throw e; }

Prevention

Encapsulate test setup in one helper that always sets clientFactory and clock together.
Centralize fake-client construction so the pair cannot drift apart during refactors.

When it happens

Trigger: Constructing PubsubReadSchemaTransformProvider (e.g. via its builder) with only clientFactory set or only clock set, then calling from()/pubsubRead() to build the read transform — typically in unit tests.

Common situations: Test code that was updated to set the clock but forgot the client factory (or vice versa); refactoring that moved one of the two settings; partially copied test setup from another test class.

Related errors

AI-assisted analysis of apache/beam@12126d8942 (2026-09-13). Data as JSON: /api/errors/bfa2ed2208a862c1. Report an issue: GitHub.

Appendix: source

Thrown at sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/pubsub/PubsubReadSchemaTransformProvider.java:273

              ? PubsubIO.readMessages()
              : PubsubIO.readMessagesWithAttributes();
      String topic = configuration.getTopic();
      if (topic != null && !topic.isEmpty()) {
        pubsubRead = pubsubRead.fromTopic(topic);
      } else {
        String subscription = configuration.getSubscription();
        pubsubRead =
            pubsubRead.fromSubscription(
                checkArgumentNotNull(
                    subscription, "Either topic or subscription must be specified"));
      }
      final PubsubTestClientFactory clientFactory = this.clientFactory;
      final Clock clock = this.clock;
      if (clientFactory != null && clock != null) {
        pubsubRead = pubsubRead.withClientFactory(clientFactory);
        pubsubRead = clientFactory.setClock(pubsubRead, clock);
      } else if (clientFactory != null || clock != null) {
        throw new IllegalArgumentException(
            "Both PubsubTestClientFactory and Clock need to be specified for testing, but only one is provided");
      }
      String idAttribute = configuration.getIdAttribute();
      if (idAttribute != null && !idAttribute.isEmpty()) {
        pubsubRead = pubsubRead.withIdAttribute(idAttribute);
      }
      String timestampAttribute = configuration.getTimestampAttribute();
      if (timestampAttribute != null && !timestampAttribute.isEmpty()) {
        pubsubRead = pubsubRead.withTimestampAttribute(timestampAttribute);
      }
      return pubsubRead;
    }

    @Override
    public PCollectionRowTuple expand(PCollectionRowTuple input) {
      PubsubIO.Read<PubsubMessage> pubsubRead = buildPubsubRead();
      PubsubReadSchemaTransformConfiguration.ErrorHandling errorHandling =
          configuration.getErrorHandling();

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