Re: [PATCH 1/5] t7300: add testcase showing unnecessary traversal into ignored directory

> I think I figured it out.  I now have the test simplified down to just:
>
> test_expect_success 'avoid traversing into ignored directories' '
>     test_when_finished rm -f output error trace.* &&
>     test_create_repo avoid-traversing-deep-hierarchy &&
>     (
>         mkdir -p untracked/subdir/with/a &&
>         >untracked/subdir/with/a/random-file.txt &&
>
>         GIT_TRACE2_PERF="$TRASH_DIRECTORY/trace.output" \
>         git clean -ffdxn -e untracked &&
>
>         grep data.*read_directo.*visited ../trace.output \
>             | cut -d "|" -f 9 >../trace.relevant &&
>         cat >../trace.expect <<-EOF &&
>         directories-visited:1
>         paths-visited:4
>         EOF
>         test_cmp ../trace.expect ../trace.relevant
>     )
> '

> This relies on a few extra changes to the code: (1) switching the
> existing trace calls in dir.c over to using trace2 variants, and (2)
> adding two new counters (visited_directories and visited_paths) that
> are output using the trace2 framework.  I'm a little unsure if I
> should check the paths-visited counter (will some platform have
> additional files in every directory besides '.' and '..'?  Or not have
> one of those?), but it is good to have it check that the code in this
> case visits no directories other than the toplevel one (i.e. that
> directories-visited is 1).