[KAFKA-12861] MockProducer raises NPE when no Serializer

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.7.0, 2.8.0, 2.7.1
• Component/s: clients
• Assignee: Unassigned
• Reporter: Gérald Quintana
• Created: 28/May/21 15:36
• Updated: 28/May/21 15:36

Description

Since KAFKA-10503, the MockProducer may raise NullPointerException when key/value serializers are not set:

java.lang.NullPointerException: null
  at org.apache.kafka.clients.producer.MockProducer.send(MockProducer.java:307)

This occurs when using MockProducer default constructor:

public MockProducer() {
 this(Cluster.empty(), false, null, null, null);
}

The problem didn't occur on Kafka Client 2.6.

I understand this constructor is only for metadata as described in JavaDoc. However defaulting to a Noop serializer (MockSerializer) would be a better default. Removing the default constructor to force declaring a serialiszer could also be a solution.