Скачать или смотреть Resolving the Issue of @ Autowired Not Working in Spring Boot Unit Tests

Learn how to fix `@ Autowired` not working in your Spring Boot unit tests by understanding the correct testing practices and setup.
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Understanding the Issue: @ Autowired Not Working in Spring Boot Unit Tests

Spring Boot is a powerful framework that simplifies Java development, particularly when it comes to dependency management. The @ Autowired annotation allows you to seamlessly inject dependencies managed by Spring. However, it's not uncommon to encounter situations where it doesn't work as intended, especially during unit tests.
In this guide, we will explore a common issue with @ Autowired in Spring Boot unit tests and how to effectively resolve it.

The Problem

In the provided case, a developer attempts to inject a Parser bean using @ Autowired in a unit test but faces a NullPointerException when invoking the parseStrings method. This implies that the Parser object hasn’t been properly instantiated and subsequently leads to the test failure.

Possible Root Cause

The use of MockitoJUnitRunner suggests a reliance on mocking, while the class being tested does not have any dependencies that require mocking in this context. This might cause the Spring context to not load as expected during the test.

The Solution

To resolve the issue of @ Autowired not working in your tests, consider the following steps:

1. Adjust Your Test Setup

If your class does not depend on other beans, your unit test can be simplified. Instead of relying on dependency injection, you can directly instantiate the Parser class in the test setup.

Here’s how you can modify the test:

[[See Video to Reveal this Text or Code Snippet]]

2. Use the Correct Runner

If you truly don't need any mocks and your test is focused on a simple functionality check, you can remove the @ RunWith annotation since JUnit 5 does not require it:

[[See Video to Reveal this Text or Code Snippet]]

3. Understanding the Need for an Autowired or Spring Context

When to Use @ Autowired: Use @ Autowired when your class has dependencies on other beans that need to be injected. In unit tests, this is typically avoided unless you're performing integration tests.

Integration Tests: When you need to run integration tests involving multiple layers of your application, consider using @ SpringBootTest which will load the entire Spring context.

Conclusion

In summary, if you're facing issues with @ Autowired in your Spring Boot unit tests, consider whether you actually need to use dependency injection in the test scenario or if a simple instantiation of the class will suffice. By directly creating an instance of the class you want to test and tailoring your test setup accordingly, you can resolve injection issues and ensure your tests run smoothly.

Now you're equipped to avoid @ Autowired pitfalls in your Spring Boot unit tests. Happy coding!