Dedicated unit tests for django_spanner

[c24t]

RIght now there's 0%(!) coverage for django_spanner, but django tests cover most of this dir. Do we need separate unit tests for django_spanner? This is probably a good idea, but may be redundant with existing django tests.

[vi3k6i5]

@skuruppu : what do you think ? should we add separate unit tests?

[skuruppu]

Yeah that's a really good question. I feel that we shouldn't just add redundant tests if the existing tests already test the code. Is there some way we can setup either the existing coverage checker or a new tool to report the coverage for the existing tests?

[vi3k6i5]

okay, I will work on using coverage report from existing django unit tests.