Re: [PATCH 09/30] directory rename detection: testcases checking which side did the rename

From: Stefan Beller <sbeller@google.com>
Date: Nov 14, 2017, 00:25 UTC
Message-ID: <CAGZ79kbsQqAFGFVN3dOnSAFuPishF3PGS7_go+53T5Oa-4qWiA@mail.gmail.com>
In-Reply-To: <20171110190550.27059-10-newren@gmail.com>

On Fri, Nov 10, 2017 at 11:05 AM, Elijah Newren <newren@gmail.com> wrote:

Show 35 quoted lines

> Signed-off-by: Elijah Newren <newren@gmail.com>
> ---
>  t/t6043-merge-rename-directories.sh | 283 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 283 insertions(+)
>
> diff --git a/t/t6043-merge-rename-directories.sh b/t/t6043-merge-rename-directories.sh
> index d15153c652..157299105f 100755
> --- a/t/t6043-merge-rename-directories.sh
> +++ b/t/t6043-merge-rename-directories.sh
> @@ -1053,4 +1053,287 @@ test_expect_failure '5d-check: Directory/file/file conflict due to directory ren
>  #   back to old handling.  But, sadly, see testcases 8a and 8b.
>  ###########################################################################
>
> +
> +###########################################################################
> +# SECTION 6: Same side of the merge was the one that did the rename
> +#
> +# It may sound obvious that you only want to apply implicit directory
> +# renames to directories if the _other_ side of history did the renaming.
> +# If you did make an implementation that didn't explicitly enforce this
> +# rule, the majority of cases that would fall under this section would
> +# also be solved by following the rules from the above sections.  But
> +# there are still a few that stick out, so this section covers them just
> +# to make sure we also get them right.
> +###########################################################################
> +
> +# Testcase 6a, Tricky rename/delete
> +#   Commit A: z/{b,c,d}
> +#   Commit B: z/b
> +#   Commit C: y/{b,c}, z/d
> +#   Expected: y/b, CONFLICT(rename/delete, z/c -> y/c vs. NULL)
> +#   Note: We're just checking here that the rename of z/b and z/c to put
> +#         them under y/ doesn't accidentally catch z/d and make it look like
> +#         it is also involved in a rename/delete conflict.
> +

Show 6 quoted lines

> +
> +# Testcase 6b, Same rename done on both sides
> +#   (Related to testcases 6c and 8e)
> +#   Commit A: z/{b,c}
> +#   Commit B: y/{b,c}
> +#   Commit C: y/{b,c}, z/d

Missing expected state

> +#   Note: If we did directory rename detection here, we'd move z/d into y/,
> +#         but C did that rename and still decided to put the file into z/,
> +#         so we probably shouldn't apply directory rename detection for it.

correct. Also we don't want to see a rename/rename conflict (obviously).

If we have

    Commit A: z/{b_1,c}
    Commit B: y/{b_2,c}
    Commit C: y/{b_3,c}, z/d

then we'd produce a standard file merge (which may or may not result in conflict, depending on touched lines) for y/b_{try-resolve}

Show 9 quoted lines

> +
> +# Testcase 6c, Rename only done on same side
> +#   (Related to testcases 6b and 8e)
> +#   Commit A: z/{b,c}
> +#   Commit B: z/{b,c} (no change)
> +#   Commit C: y/{b,c}, z/d
> +#   Expected: y/{b,c}, z/d
> +#   NOTE: Seems obvious, but just checking that the implementation doesn't
> +#         "accidentally detect a rename" and give us y/{b,c,d}.

makes sense.

Show 9 quoted lines

> +
> +# Testcase 6d, We don't always want transitive renaming
> +#   (Related to testcase 1c)
> +#   Commit A: z/{b,c}, x/d
> +#   Commit B: z/{b,c}, x/d (no change)
> +#   Commit C: y/{b,c}, z/d
> +#   Expected: y/{b,c}, z/d
> +#   NOTE: Again, this seems obvious but just checking that the implementation
> +#         doesn't "accidentally detect a rename" and give us y/{b,c,d}.

makes sense, too.

Show 8 quoted lines

> +# Testcase 6e, Add/add from one-side
> +#   Commit A: z/{b,c}
> +#   Commit B: z/{b,c} (no change)
> +#   Commit C: y/{b,c,d_1}, z/d_2
> +#   Expected: y/{b,c,d_1}, z/d_2
> +#   NOTE: Again, this seems obvious but just checking that the implementation
> +#         doesn't "accidentally detect a rename" and give us y/{b,c} +
> +#         add/add conflict on y/d_1 vs y/d_2.

What is less obvious in all these cases is the "(no change)" part to me. I would think that at least *something* changes in B in all cases above, maybe add file u/r (un-related) to have the tree ids changed? ("Less obvious" as in: we don't rely on the "no changes" part to make the decision, which sounds tempting so far)

>  test_done

No conclusion box here, so my (misguided) suggestion:

  If "No change" occurs, just take the other side. ;)