Introduce NON_EXTENSIBLE JSON assertion support in spring-test

[membersound]

Please add a method for JSONCompareMode.NON_EXTENSIBLE to JsonExpectationsHelper in spring-test.

Because: mostly you want to assert that both requests contain exactly the same content and the same fields. But order of elements usually does not matter, as json is nothing other than a HashMap.

That's simply not possible to assert as of now.

NON_EXTENSIBLE is the correct mode in that case.

[sbrannen]

JsonExpectationsHelper is primarily intended for use within the framework itself, and it is essentially just a wrapper around org.skyscreamer.jsonassert.JSONAssert.

If you have been using JsonExpectationsHelper directly in your code and want to make use of JSONCompareMode, we would recommend that you instead use JSONAssert.

Or... are you hoping to see more lenient matching in classes such as org.springframework.test.web.client.match.ContentRequestMatchers, org.springframework.test.web.servlet.result.ContentResultMatchers, and org.springframework.test.web.reactive.server.WebTestClient?

[membersound]

Ok indeed that would make sense to directly use JSONAssert.
Still, if there is room for improved lenient json matching directly in the ContentMatchers, that would also be nice.

[sbrannen]

Actually, we already have support for choosing between lenient and strict matching:

• org.springframework.test.web.client.match.ContentRequestMatchers.json(String, boolean)
• org.springframework.test.web.servlet.result.ContentResultMatchers.json(String, boolean)

If you supply true for the above strict flags, JSONCompareMode.STRICT is used, but if you supply false that switches to JSONCompareMode.LENIENT.

Those delegate to JsonExpectationsHelper.assertJsonEqual(String, String, boolean) which in turn delegates to org.skyscreamer.jsonassert.JSONAssert.assertEquals(String, String, boolean).

Please note as well that JsonExpectationsHelper.assertJsonEqual(String, String) applies lenient matching by default, and that is used by DefaultWebTestClient.DefaultBodyContentSpec.json(String).

In light of that, I'm going to close this issue.

[membersound]

If you supply true for the above strict flags, JSONCompareMode.STRICT is used, but if you supply false that switches to JSONCompareMode.LENIENT.

Well but that's exactly the problem: LENIENT will not detect of one of the comparable values contains additional elements. You mostly don't want that. STRICT fixes this, but requires strict order of elements. Which for a json hashmap is kind of useless, as json is per definition unsorted.

Thus, one should mostly use the NON_EXTENSIBLE mode (which does not allow additional elements, but allows different order). And this mode is afaik not possible with ContentRequestMatchers or ContentResultMatchers.

Wouldn't it be worth extending the testclasses so that either JSONCompareMode can be supplied as parameter, or add a NON_EXTENSIBLE matcher method explicit?

To add some insight on a real world case: yesterday I discovered that some of my JUnit tests should have failed because in one of the json items, there was introduced a new field. But they did not, as by default the lenient mode explicit allows this behavior. And mostly this will be unintended, also for other users. I assume.