Mock Kafka Message Generator

How to use

1. 1️⃣
   Choose your options above
2. 2️⃣
   Click Generate
3. 3️⃣
   Copy your result

Detailed instructions

1. Enter your Kafka topic name in the Topic Name field to match your actual topic, e.g. order-service.events.
2. Select the Event Type that matches the domain you are testing — user.created, order.placed, or payment.processed.
3. Set the How Many counter to the number of records your test scenario requires, then click Generate.
4. Copy the generated JSON array and paste it into your unit test, MockConsumer setup, or kafka-console-producer input file.
5. Adjust individual field values in the copied payload to cover edge cases like null amounts or missing user IDs.

Use Cases

• •Seeding a Kafka Streams TestInputTopic with realistic user.created events inside a JUnit 5 test suite
• •Testing Spring Kafka @KafkaListener offset-commit logic using MockConsumer with generated record batches
• •Creating dead-letter queue handler fixtures by generating payment.processed messages with edge-case field values
• •Demoing Kafka record anatomy — headers, UUID key, partition, offset — during microservices onboarding sessions
• •Replaying order.placed message batches through kafka-console-producer against a local Docker Kafka broker

Tips

• →Match the topic name exactly to your environment's naming convention so generated messages need no editing before use in tests.
• →Generate a batch of 10 or more, then cherry-pick specific records to cover both happy-path and failure scenarios in the same test suite.
• →The message key is a UUID by default — replace it with a fixed value when testing partition-ordered processing to ensure all test records land on the same partition.
• →Copy the headers object into a Spring Kafka MessageHeaders or a Flink KafkaRecordSerializationSchema to test header-aware consumer branches.
• →Combine payment.processed and user.created events in a single test to verify that your consumer correctly routes multiple event types from the same topic.
• →When testing offset-commit logic, edit the offset field in consecutive generated records to be sequential integers starting from a non-zero value, simulating a mid-stream consumer restart.

FAQ