[PATCH 11/15] tests: Add a utility class to create Series

[Finucane, Stephen]

> So far we've been using real emails stored on-disk. While it's
> interesting to have real data as input for unit tests, it's not as
> flexible as having generated data. With generated data we can easily
> create corner cases to improve the test coverage of the parsing code.
> 
> This is just a start, adding a TestSeries classes that can create a
> series with n patches with or without a cover letter.
> 
> Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>

All tests and they look good to me.

Acked-by: Stephen Finucane <stephen.finucane at intel.com>