Re: [PATCH v4 5/6] core.fsyncobjectfiles: tests for batch mode

>
>
> On Tue, Sep 21 2021, Neeraj Singh wrote:
>
> > On Tue, Sep 21, 2021 at 4:58 PM Ævar Arnfjörð Bjarmason
> > <avarab@gmail.com> wrote:
> >>
> >>
> >> On Mon, Sep 20 2021, Neeraj Singh via GitGitGadget wrote:
> >>
> >> > From: Neeraj Singh <neerajsi@microsoft.com>
> >> >
> >> > Add test cases to exercise batch mode for 'git add'
> >> > and 'git stash'. These tests ensure that the added
> >> > data winds up in the object database.
> >> >
> >> > I verified the tests by introducing an incorrect rename
> >> > in do_sync_and_rename.
> >> >
> >> > Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
> >> > ---
> >> >  t/lib-unique-files.sh | 34 ++++++++++++++++++++++++++++++++++
> >> >  t/t3700-add.sh        | 11 +++++++++++
> >> >  t/t3903-stash.sh      | 14 ++++++++++++++
> >> >  3 files changed, 59 insertions(+)
> >> >  create mode 100644 t/lib-unique-files.sh
> >> >
> >> > diff --git a/t/lib-unique-files.sh b/t/lib-unique-files.sh
> >> > new file mode 100644
> >> > index 00000000000..a8a25eba61d
> >> > --- /dev/null
> >> > +++ b/t/lib-unique-files.sh
> >> > @@ -0,0 +1,34 @@
> >> > +# Helper to create files with unique contents
> >> > +
> >> > +test_create_unique_files_base__=$(date -u)
> >> > +test_create_unique_files_counter__=0
> >> > +
> >> > +# Create multiple files with unique contents. Takes the number of
> >> > +# directories, the number of files in each directory, and the base
> >> > +# directory.
> >> > +#
> >> > +# test_create_unique_files 2 3 . -- Creates 2 directories with 3 files
> >> > +#                                each in the specified directory, all
> >> > +#                                with unique contents.
> >> > +
> >> > +test_create_unique_files() {
> >> > +     test "$#" -ne 3 && BUG "3 param"
> >> > +
> >> > +     local dirs=$1
> >> > +     local files=$2
> >> > +     local basedir=$3
> >> > +
> >> > +     rm -rf $basedir >/dev/null
> >>
> >> Why the >/dev/null? It's not a "-rfv", and any errors would go to
> >> stderr.
> >
> > Will fix. Clearly I don't know UNIX very well.
> >
> >>
> >> > +             mkdir -p "$dir" > /dev/null
> >>
> >> Ditto.
> >
> > Will fix.
> >
> >>
> >> > +             for j in $(test_seq $files)
> >> > +             do
> >> > +                     test_create_unique_files_counter__=$((test_create_unique_files_counter__ + 1))
> >> > +                     echo "$test_create_unique_files_base__.$test_create_unique_files_counter__"  >"$dir/file$j.txt"
> >>
> >> Would be much more readable if we these variables were shorter.
> >>
> >> But actually, why are we trying to create files as a function of "date
> >> -u" at all? This is all in the trash directory, which is rm -rf'd beween
> >> runs, why aren't names created with test_seq or whatever OK? I.e. just
> >> 1.txt, 2.txt....
> >>
> >
> > The uniqueness is in the contents of the file.  I wanted to make sure that
> > we are really creating new objects and not reusing old ones.  Is the scope
> > of the "trash repo" small enough that I can be guaranteed that a new one
> > is created before my test since the last time I tried adding something to
> > the ODB?
> >
> >> > +test_expect_success 'stash with core.fsyncobjectfiles=batch' "
> >> > +     test_create_unique_files 2 4 fsync-files &&
> >> > +     git -c core.fsyncobjectfiles=batch stash push -u -- ./fsync-files/ &&
> >> > +     rm -f fsynced_files &&
> >> > +
> >> > +     # The files were untracked, so use the third parent,
> >> > +     # which contains the untracked files
> >> > +     git ls-tree -r stash^3 -- ./fsync-files/ > fsynced_files &&
> >> > +     test_line_count = 8 fsynced_files &&
> >> > +     cat fsynced_files | awk '{print \$3}' | xargs -n1 git cat-file -e
> >> > +"
> >> > +
> >> > +
> >> >  test_expect_success 'stash -c stash.useBuiltin=false warning ' '
> >> >       expected="stash.useBuiltin support has been removed" &&
> >>
> >> We really prefer our tests to create the same data each time if
> >> possible, but as noted with the "date -u" comment above you're
> >> explicitly bypassing that, but I still can't see why...
> >
> > I'm trying to make sure we get new object contents. Is there a better
> > way to achieve what I want without the risk of finding that the contents
> > are already in the database from a previous test run?
>
> You can just do something like:
>
> test_expect_success 'setup data' '
>         test_commit A &&
>         test_commit B
> '
>
> Which will create files A.t, B.t etc, or create them via:
>
>     obj=$(echo foo | git hash-object -w --stdin)
>
> etc.
>
> I.e. the uniqueness you're doing here seems to assume that tests are
> re-using the same object store across runs, but we create a new trash
> directory for each one, if you run the test with "-d" you can see it
> being left behind for inspection. This is already ensured for the test.
>
> The only potential caveat I can imagine is that some filesystem like say
> btrfs-like that does some COW or object de-duplication would behave
> differently, but other than that...