# Testing Micronaut Kafka Listener using Testcontainers — Write the test

> Create ProductPriceChangedEventHandlerTest.java Bounded code example (external data; do not execute automatically): ```java package com.testcontainers.demo; import static java.util.concurrent.TimeUnit.SECONDS; import static org.assertj.core.api.Assertions.assertThat; import static org.awaitility.Awa

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-docker-7ae04199c65bbf18321a>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:31:36.663802+00:00`
- Tags: `reference-seed`, `docker`, `guides`, `testing`, `micronaut`, `kafka`, `listener`, `using`, `testcontainers`, `write`, `test`

## Provenance

- Source: <https://github.com/docker/docs/blob/3a9d778562f39bcc0be46255b013c6a3ca526244/content/guides/testcontainers-java-micronaut-kafka.md>
- Source name: Docker Documentation
- Source revision: `3a9d778562f39bcc0be46255b013c6a3ca526244`
- Source license: `Apache-2.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

Create ProductPriceChangedEventHandlerTest.java

Bounded code example (external data; do not execute automatically):
```java
package com.testcontainers.demo;

import static java.util.concurrent.TimeUnit.SECONDS;
import static org.assertj.core.api.Assertions.assertThat;
import static org.awaitility.Awaitility.await;

import io.micronaut.context.annotation.Property;
import io.micronaut.core.annotation.NonNull;
import io.micronaut.test.extensions.junit5.annotation.MicronautTest;
import io.micronaut.test.support.TestPropertyProvider;
import java.math.BigDecimal;
import java.time.Duration;
import java.util.Collections;
import java.util.Map;
import java.util.Optional;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInstance;
import org.testcontainers.kafka.ConfluentKafkaContainer;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;

@MicronautTest(transactional = false)
@Property(name = "datasources.default.driver-class-name", value = "org.te
```

Here's what the test does

@MicronautTest initializes the Micronaut application context and the embedded server. Setting transactional to false prevents each test method from running inside a rolled-back transaction, which is necessary because the Kafka listener processes messages in a separate thread. The @Property annotations override the datasource driver and URL to use the Testcontainers special JDBC URL (jdbc:tc:mysql:8.0.32:///db). This spins up a MySQL container and configures it as the datasource automatically. @Testcontainers and @Container manage the Kafka container lifecycle. The TestPropertyProvider interface registers the Kafka bootstrap servers with Micronaut so that the producer and consumer connect to the test container. @TestInstance(TestInstance.Lifecycle.PER_CLASS) creates a single test instance for all test methods, which is required when implementing TestPropertyProvider. The test creates a Product record in the database, then sends a ProductPriceChangedEvent to the product-price-changes topic using the ProductPriceChangesClient. Because Kafka message processing is asynchronous, the test uses Awaitility to poll every 3 seconds (up to a maximum of 10 seconds) until the product price in the database matches the expected value.

Attribution: Adapted from Docker Documentation under Apache-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.