Re: [PATCH v1 1/2] t0027: Correct raciness in NNO test

From: Johannes Sixt <j6t@kdbg.org>
To: tboegi@web.de
Cc: git@vger.kernel.org, peff@peff.net, Johannes.Schindelin@gmx.de
Subject: Re: [PATCH v1 1/2] t0027: Correct raciness in NNO test
Date: Sat, 13 Aug 2016 18:50:19 +0200	[thread overview]
Message-ID: <57AF4FCB.7090409@kdbg.org> (raw)
In-Reply-To: <1471020662-20746-1-git-send-email-tboegi@web.de>

Am 12.08.2016 um 18:51 schrieb tboegi@web.de:
> From: Torsten Bögershausen <tboegi@web.de>
>
> When a non-reversible CRLF conversion is done in "git add",
> a warning is printed on stderr (or Git dies, depending on checksafe)
>
> The function commit_chk_wrnNNO() in t0027 was written to test this,
> but did the wrong thing: Instead of looking at the warning
> from "git add", it looked at the warning from "git commit".
>
> This is racy because "git commit" may not have to do CRLF conversion
> at all if it can use the sha1 value from the index (which depends on
> whether "add" and "commit" run in a single second).
>
> Correct this and replace the commit for each and every file with a commit
> of all files in one go.

The new test code does not only fix the race condition, but also tests 
different things, or prepares test cases in a different manner. I would 
have appreciated an explanation why this is necessary. Is it "on my 
machine, the race condition was triggered consistently for a bunch of 
tests, and so I recorded the wrong expected output in the test cases"?

>
> The function commit_chk_wrnNNO() will to be renamed in a separate commit.
> Thanks to Jeff King <peff@peff.net> for analyzing t0027.
>
> Reported-By: Johannes Schindelin <Johannes.Schindelin@gmx.de>
> ---
>   t/t0027-auto-crlf.sh | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/t/t0027-auto-crlf.sh b/t/t0027-auto-crlf.sh
> index 2860d2d..ab6e962 100755
> --- a/t/t0027-auto-crlf.sh
> +++ b/t/t0027-auto-crlf.sh
> @@ -119,8 +119,7 @@ commit_chk_wrnNNO () {
>   		fname=${pfx}_$f.txt &&
>   		cp $f $fname &&
>   		printf Z >>"$fname" &&
> -		git -c core.autocrlf=$crlf add $fname 2>/dev/null &&
> -		git -c core.autocrlf=$crlf commit -m "commit_$fname" $fname >"${pfx}_$f.err" 2>&1
> +		git -c core.autocrlf=$crlf add $fname 2>"${pfx}_$f.err"
>   	done
>
>   	test_expect_success "commit NNO files crlf=$crlf attr=$attr LF" '
> @@ -394,11 +393,11 @@ test_expect_success 'commit files attr=crlf' '
>
>   #                 attr                    LF        CRLF      CRLFmixLF   LF_mix_CR   CRLFNUL
>   commit_chk_wrnNNO ""      ""      false   ""        ""        ""          ""          ""
> -commit_chk_wrnNNO ""      ""      true    LF_CRLF   ""        ""          ""          ""
> +commit_chk_wrnNNO ""      ""      true    ""        ""        ""          ""          ""
>   commit_chk_wrnNNO ""      ""      input   ""        ""        ""          ""          ""
>
> -commit_chk_wrnNNO "auto"  ""      false   "$WILC"   ""        ""          ""          ""
> -commit_chk_wrnNNO "auto"  ""      true    LF_CRLF   ""        ""          ""          ""
> +commit_chk_wrnNNO "auto"  ""      false   ""        ""        ""          ""          ""
> +commit_chk_wrnNNO "auto"  ""      true    ""        ""        ""          ""          ""
>   commit_chk_wrnNNO "auto"  ""      input   ""        ""        ""          ""          ""
>   for crlf in true false input
>   do
> @@ -408,7 +407,7 @@ do
>   	commit_chk_wrnNNO ""    lf      $crlf   ""       CRLF_LF    CRLF_LF      ""         CRLF_LF
>   	commit_chk_wrnNNO ""    crlf    $crlf   LF_CRLF   ""        LF_CRLF     LF_CRLF     ""
>   	commit_chk_wrnNNO auto  lf    	$crlf   ""        ""        ""          ""          ""
> -	commit_chk_wrnNNO auto  crlf  	$crlf   LF_CRLF   ""        ""          ""          ""
> +	commit_chk_wrnNNO auto  crlf  	$crlf   ""        ""        ""          ""          ""
>   	commit_chk_wrnNNO text  lf    	$crlf   ""       CRLF_LF    CRLF_LF     ""          CRLF_LF
>   	commit_chk_wrnNNO text  crlf  	$crlf   LF_CRLF   ""        LF_CRLF     LF_CRLF     ""
>   done
> @@ -417,7 +416,8 @@ commit_chk_wrnNNO "text"  ""      false   "$WILC"   "$WICL"   "$WAMIX"    "$WILC
>   commit_chk_wrnNNO "text"  ""      true    LF_CRLF   ""        LF_CRLF     LF_CRLF     ""
>   commit_chk_wrnNNO "text"  ""      input   ""        CRLF_LF   CRLF_LF     ""          CRLF_LF
>
> -test_expect_success 'create files cleanup' '
> +test_expect_success 'commit NNO and cleanup' '
> +	git commit -m "commit files on top of NNO" &&
>   	rm -f *.txt &&
>   	git -c core.autocrlf=false reset --hard
>   '
>