Unit testing

[NicoPolazzi]

I was reading the testing documentation and I find that it could be useful if you can give me some advice on how to write unit and integration test of a Spring Batch application.

[scordio]

Hi @NicoPolazzi, in my experience, pure JUnit tests are usually enough for unit tests without needing any test utility from the Spring projects. See also this Spring Boot blog post, which mentions:

The easiest way to unit test any Spring @Component is to not involve Spring at all! It’s always best to try and structure your code so that classes can be instantiated and tested directly. Usually that boils down to a few things:

• Structure your code with clean separation of concerns so that individual parts can be unit tested. TDD is a good way to achieve this.
• Use constructor injection to ensure that objects can be instantiated directly. Don’t use field injection as it just makes your tests harder to write.

Here the emphasis is on Spring components, but I find the same advice applicable to Spring Batch elements as well, such as a custom ItemProcessor (which might or might not be annotated with @Component).

Regarding integration tests, here is an example that is close enough to how I generally test Spring Batch in real-world Spring Boot applications. The main point is disabling the automated job startup logic of Spring Boot via the spring.batch.job.enabled=false property, and starting up the job programmatically via JobOperatorTestUtils.

@IntegrationTest is my custom composed annotation that aggregates the @SpringBootTest setup with the @SpringBatchTest declaration (and can also contain test suite specific details, like the @EnableWireMock in my example).

If I recall correctly, the documentation intentionally avoids mentioning Spring Boot, which is why only the Spring Framework's @SpringJUnitConfig is demonstrated alongside @SpringBatchTest.

However, nowadays it might be quite rare to use Spring Batch without Spring Boot, but that's just my personal opinion.

[NicoPolazzi]

Thank you for your exhaustive answer, it clarifies my doubts and it'll be helpful in my developments.