Functional testing plan (test cases, e.g. for non-technical manual pre-release testing)

[Aleksej]

Some quotes from IRC: ======

::

    <paroneayea> I think there's two things to that, we could use more unit tests, but we could also really use a functional testing plan
                 that is, a list of steps that somewhere before release time people can go through and test the software and make sure everything is working as expected
    …
    <paroneayea> we could probably use omgmg for it.
    …
    <AVRS> Mozilla uses Litmus, but it's going to be replaced.
    …
    <paroneayea> even just a wiki page detailing procedures would be good, but a better tool like Litmus or a replacement would be nice
    
    <paroneayea> so this type of testing is less technical
                 it's more like you list a whole bunch of steps to test
                 like, submit a large image, see if it resizes right
                 register with a goofy username, see if it breaks
                 etc
                 make sure that all of the expected functionality works from a user-clicking-through perspective

=======

Example of Litmus test results:
`https://litmus.mozilla.org/search\_results.cgi?test\_run\_id=83 <https://litmus.mozilla.org/search_results.cgi?test_run_id=83>`_