Fix introspection of list field in schema

[limdauto]

I hope the commit is self-explanatory. Please let me know if you need more information.

[carltongibson]

@limdauto I think we need a test case to cover the intended behaviour here. (Not least because we want to avoid regressions as the schema generation code grows/matures.)

[limdauto]

@carltongibson hi thanks for the feedback I have just realized that this fixes a known issue: #5311 i will add a test case this weekend.

[carltongibson]

@limdauto Awesome. Thanks!

[limdauto]

@carltongibson sorry I was moving house last week so only got a chance to do it now. I have added a test.

As a general question, the test suite for schema generation seems to be all integration test, i.e. we need to make a call to the API and get back the schema to check for validity. So it takes a bit of extra effort to test smaller fixes like this. What's your opinion of introducing more unit tests to some lower-level methods?

[carltongibson]

What's your opinion of introducing more unit tests to some lower-level methods?

I all for that!

Aside: this is all still new. First batch of tests are deliberately high-level: "Does it all work?". As it matures, yes, we need to move to more targeted testing.

[carltongibson]

Lovely. Thank you very much!