Test support of DRF HyperlinkedIdentityField

[Alig1493]

Fixes #298

Description of the Change

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• changelog entry added to CHANGELOG.md
• author name in AUTHORS

[Alig1493]

@sliverc I added a test for blog HyperlinkedIdentityField relationship with Entry. It seems the error arises when we we use a non model field to serialize the relationship. If we use a model field name directly then no related links are produced for the blogs and we just a simple blog data without related links.

I can try and look deeper into the issue, not sure if I'll be able to solve it. Will you be able to at least tell me where I might start looking to try and debug this case?

[sliverc]

It seems that HyperlinkedIdentityField doesn't support source attribute to be overwritten.

That's why an exception is raised. This should not concern us though as it is not correctly used. So best adjust your test case that we focus on simply using HyperlinkedIdentityField and see that it renders correctly.

[Alig1493]

@sliverc I rewrote the tests using default drf serializers to see if the entry works with hyperlinkedrelated field. No issue so far.

[sliverc]

A few small changes and this will be ready for merging.

[Alig1493]

@sliverc Made requested changes

[sliverc]

@Alig1493 Thanks.