Include Spring Boot's JacksonTester in the test module

[odrotbohm]

Spring Boot ships JacksonTester (see Boot's reference docs) that's very handy to formulate assertions on Jackson rendered payloads. That kind of functionality is very helpful for tests in Spring projects that deal with Jackson serialization (Spring HATEOAS, Spring Data REST) and it doesn't look like the class is tied to Boot in any way.

That said, it refers to AssertJ as assertion library but there seem to be quite a few themes regarding the integration of AssertJ APIs in e.g. MockMVC already.

[bclozel]

We've discussed this issue as a team and we think that while this feature would be a nice addition to our testing support, we don't think that it's worth investing in it right now. This feature has been available in Spring Boot for a while now and as you've pointed out, this also requires a broader adoption of AssertJ in our testing support.

We'll turn this issue into a documentation improvement - we should add a new section in the Integration testing reference documentation to cross-link to the Spring Boot support.

We might revisit this decision in the future, if and once AssertJ adoption is broader in spring-test.

[odrotbohm]

Now that AssertJ testing support has landed in 6.2, is it worth reconsidering this?