[jira] [Commented] (KAFKA-5253) TopologyTestDriver must handle streams created with patterns

["Matthias J. Sax (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-5253?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16354332#comment-16354332 ] 

Matthias J. Sax commented on KAFKA-5253:
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I doubled checked {{TopologyTestDriver}} and it is not able to handle Pattern subscription. The fix should be fairly easy, however, required a public API change and thus a KIP.

> TopologyTestDriver must handle streams created with patterns
> ------------------------------------------------------------
>
>                 Key: KAFKA-5253
>                 URL: https://issues.apache.org/jira/browse/KAFKA-5253
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams, unit tests
>    Affects Versions: 1.1.0
>            Reporter: Wim Van Leuven
>            Priority: Major
>              Labels: beginner, needs-kip, newbie
>
> *Context*
>  -KStreamTestDriver- TopologyTestDriver (added via KIP-247) is being used to unit test topologies while developing KStreams apps.
> One such topology uses a Pattern to consume from multiple topics at once.
> *Problem*
>  The unit test of the topology fails because -KStreamTestDriver- TopologyTestDriver fails to deal with Patterns properly.
> *Example*
>  Underneath is a unit test explaining what I understand should happen, but is failing.
> Explicitly adding a source topic matching the topic pattern, generates an exception as the topology builder explicitly checks overlapping topic names and patterns, in any order of adding pattern and topic. So, it is intended behaviour.
> {code:java}
>     @Test
>     public void shouldProcessFromSourcesThatDoMatchThePattern() {
>         // -- setup stream pattern
>         final KStream<String, String> source = builder.stream(Pattern.compile("topic-source-\\d"));
>         source.to("topic-sink");
>         // -- setup processor to capture results
>         final MockProcessorSupplier<String, String> processorSupplier = new MockProcessorSupplier<>();
>         source.process(processorSupplier);
>         // -- add source to stream data from
>         //builder.addSource(builder.newName(KStreamImpl.SOURCE_NAME), "topic-source-3");
>         // -- build test driver
>         driver = new KStreamTestDriver(builder);
>         driver.setTime(0L);
>         // -- test
>         driver.process("topic-source-3", "A", "aa");
>         // -- validate
>         // no exception was thrown
>         assertEquals(Utils.mkList("A:aa"), processorSupplier.processed);
>     }
> {code}
> *Solution*
>  If anybody can help in defining the solution, I can create a pull request for this change.



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