[KAFKA-10503] MockProducer doesn't throw ClassCastException when no partition for topic

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.6.0
• Fix Version/s: 2.7.0
• Component/s: clients, producer
• Labels: mock producer
• Assignee: Gonzalo Muñoz
• Reporter: Gonzalo Muñoz
• Created: 19/Sep/20 13:13
• Updated: 09/Dec/21 10:34
• Resolved: 01/Oct/20 05:31

Description

Though MockProducer admits serializers in its constructors, it doesn't check during send method that those serializers are the proper ones to serialize key/value included into the ProducerRecord.

This check is only done if there is a partition assigned for that topic.

It would be an enhancement if these serialize methods were also invoked in simple scenarios, where no partition is assigned to a topic.

eg:

    @Test
    public void shouldThrowClassCastException() {
        MockProducer<Integer, String> producer = new MockProducer<>(true, new IntegerSerializer(), new StringSerializer());
        ProducerRecord record = new ProducerRecord(TOPIC, "key1", "value1");
        try {
            producer.send(record);
            fail("Should have thrown ClassCastException because record cannot be casted with serializers");
        } catch (ClassCastException e) {}
    }

Currently, for obtaining the ClassCastException is needed to define the topic into a partition:

PartitionInfo partitionInfo = new PartitionInfo(TOPIC, 0, null, null, null);
Cluster cluster = new Cluster(null, emptyList(), asList(partitionInfo),
                                  emptySet(), emptySet());
 producer = new MockProducer(cluster, 
                                true, 
                                new DefaultPartitioner(), 
                                new IntegerSerializer(), 
                                new StringSerializer());

Issue Links

• links to: GitHub Pull Request #9309