Re: [PATCH 2/2] t9902-completion: exercise __git_complete_index_file() directly

> The tests added in 2f271cd9cf (t9902-completion: add tests
> demonstrating issues with quoted pathnames, 2018-05-08) and in
> 2ab6eab4fe (completion: improve handling quoted paths in 'git
> ls-files's output, 2018-03-28) have a few shortcomings:
>
>   - All these test use the 'test_completion' helper function, thus

>     they are exercising the whole completion machinery, although they
>     are only interested in how git-aware path completion, specifically
>     the __git_complete_index_file() function deals with unusual
>     characters in pathnames and on the command line.
>
>   - These tests can't satisfactorily test the case of pathnames
>     containing spaces, because 'test_completion' gets the words on the
>     command line as a single argument and it uses space as word
>     separator.
>
>   - Some of the tests are protected by different FUNNYNAMES_* prereqs
>     depending on whether they put backslashes and double quotes or
>     separator characters (FS, GS, RS, US) in pathnames, although a
>     filesystem not allowing one likely doesn't allow the others
>     either.
>
>   - One of the tests operates on paths containing '|' and '&'
>     characters without being protected by a FUNNYNAMES prereq, but
>     some filesystems (notably on Windows) don't allow these characters
>     in pathnames, either.
>
> Replace these tests with basically equivalent, more focused tests that
> call __git_complete_index_file() directly.  Since this function only
> looks at the current word to be completed, i.e. the $cur variable, we
> can easily include pathnames containing spaces in the tests, so use
> such pathnames instead of pathnames containing '|' and '&'.  Finally,
> use only a single FUNNYNAMES prereq for all kinds of special
> characters.
>
> Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>