Document bean override support in the TestContext framework in the reference manual

[sbrannen]

Overview

Initial documentation for bean override support in the Spring TestContext Framework (TCF) was introduced in e1bbdf0; however, that documentation resides in the appendix for the testing chapter.

The goal of this issue is therefore to introduce a dedicated subsection (in the TCF section) which documents the "Bean Override" support as a first-class feature. That section should cross-reference the @TestBean, @MockitoBean, and @MockitoSpyBean sections in the appendix.

Related Issues

• Provide a safe way to override and mock beans in the TestContext framework #29917

[snicoll]

The new dedicated section should also clearly point out the difference between the TCF support for bean overrides and Spring Boot's @MockBean/@SpyBean support

I disagree, it should not do that. New users of the feature will see the feature as documented. Existing Spring Boot users will have to follow the migration guide that Spring Boot will put in place to help users migrate. The Spring Boot feature will be deprecated and eventually removed so it does not make sense to document it here IMO.

[sbrannen]

Good points, @snicoll.

Let's omit the comparison with Spring Boot's mocking support.

I'll remove that paragraph from this issue's description.