unit-test-application-events
Testing Spring ApplicationEvent publishers and listeners with mocked dependencies and event capture patterns.
- Mock ApplicationEventPublisher in unit tests and use ArgumentCaptor to verify published events and their data integrity
- Test @EventListener method invocation directly by instantiating listeners and invoking handler methods with captured events
- Handle asynchronous event processing with Thread.sleep() or Awaitility to verify async listener completion
- Verify listener side effects on mocked dependencies and test error handling in both publishers and listeners
Unit Testing Application Events
Overview
Provides actionable patterns for testing Spring ApplicationEvent publishers and @EventListener consumers using JUnit 5 and Mockito — without booting the full Spring context.
When to Use
- Writing unit tests for event publishers or listeners
- Verifying that an event was published with correct payload
- Testing
@EventListenermethod invocation and side effects - Testing event propagation through multiple listeners
- Validating async event handling (
@Async+@EventListener) - Mocking
ApplicationEventPublisherin service tests
Instructions
- Add test dependencies:
spring-boot-starter, JUnit 5, Mockito, AssertJ - Mock ApplicationEventPublisher: use
@Mockon the publisher field in the service under test
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