Re: [PATCH 00/11] t: reduce direct disk access to data structures

> I think it would be really great if there were separate unittests for
> the ref backend API. Some of the reftable work was needlessly
> difficult because the contract of the API was underspecified. The API
> is well compartmentalized in refs-internal.h, and a lot of the API
> behavior can be tested as a black box, eg.
>
> * setup symref HEAD pointing to R1
> * setup transaction updating ref R1 from C1 to C2
> * commit transaction, check that it succeeds
> * read ref R1, check if it is C2
> * read reflog for R1, see that it has a C1 => C2 update
> * read reflog for HEAD, see that it has a C1 => C2 update
>
> Tests for the loose/packed backend could directly mess with the
> on-disk files to test failure scenarios.
>
> With unittests like that, the tests can zoom in on the functionality
> of the ref backend, and provide more convenient coverage for
> dynamic/static analysis.