Subject: Re: [PATCH v2 05/21] t1401-symbolic-ref: avoid direct filesystem access

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Thu, 20 May 2021 17:20:08 +0200

On Tue, Apr 27 2021, Han-Wen Nienhuys via GitGitGadget wrote:

> From: Han-Wen Nienhuys <[email-masked]>
>
> Signed-off-by: Han-Wen Nienhuys <[email-masked]>
> ---
>  t/t1401-symbolic-ref.sh | 34 +++++++++++++++++-----------------
>  1 file changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/t/t1401-symbolic-ref.sh b/t/t1401-symbolic-ref.sh
> index a4ebb0b65fec..315a62f78019 100755
> --- a/t/t1401-symbolic-ref.sh
> +++ b/t/t1401-symbolic-ref.sh
> @@ -3,21 +3,20 @@
>  test_description='basic symbolic-ref tests'
>  . ./test-lib.sh
>  
> -# If the tests munging HEAD fail, they can break detection of
> -# the git repo, meaning that further tests will operate on
> -# the surrounding git repo instead of the trash directory.
> -reset_to_sane() {
> -	echo ref: refs/heads/foo >.git/HEAD
> -}
> -
> -test_expect_success 'symbolic-ref writes HEAD' '
> +test_expect_success 'setup' '
>  	git symbolic-ref HEAD refs/heads/foo &&
> -	echo ref: refs/heads/foo >expect &&
> -	test_cmp expect .git/HEAD
> +	test_commit file &&
> +	"$TAR" cf .git.tar .git/
>  '
>  
> -test_expect_success 'symbolic-ref reads HEAD' '
> -	echo refs/heads/foo >expect &&
> +reset_to_sane() {
> +	rm -rf .git &&
> +	"$TAR" xf .git.tar
> +}
> +
> +test_expect_success 'symbolic-ref read/write roundtrip' '
> +	git symbolic-ref HEAD refs/heads/read-write-roundtrip &&
> +	echo refs/heads/read-write-roundtrip >expect &&
>  	git symbolic-ref HEAD >actual &&
>  	test_cmp expect actual
>  '
> @@ -25,12 +24,13 @@ test_expect_success 'symbolic-ref reads HEAD' '
>  test_expect_success 'symbolic-ref refuses non-ref for HEAD' '
>  	test_must_fail git symbolic-ref HEAD foo
>  '
> +
>  reset_to_sane
>  
>  test_expect_success 'symbolic-ref refuses bare sha1' '
> -	echo content >file && git add file && git commit -m one &&
>  	test_must_fail git symbolic-ref HEAD $(git rev-parse HEAD)
>  '
> +
>  reset_to_sane
>  
>  test_expect_success 'HEAD cannot be removed' '
> @@ -42,16 +42,16 @@ reset_to_sane
>  test_expect_success 'symbolic-ref can be deleted' '
>  	git symbolic-ref NOTHEAD refs/heads/foo &&
>  	git symbolic-ref -d NOTHEAD &&
> -	test_path_is_file .git/refs/heads/foo &&
> -	test_path_is_missing .git/NOTHEAD
> +	git rev-parse refs/heads/foo &&
> +	test_must_fail git symbolic-ref NOTHEAD
>  '
>  reset_to_sane
>  
>  test_expect_success 'symbolic-ref can delete dangling symref' '
>  	git symbolic-ref NOTHEAD refs/heads/missing &&
>  	git symbolic-ref -d NOTHEAD &&
> -	test_path_is_missing .git/refs/heads/missing &&
> -	test_path_is_missing .git/NOTHEAD
> +	test_must_fail git rev-parse refs/heads/missing &&
> +	test_must_fail git symbolic-ref NOTHEAD
>  '
>  reset_to_sane

You do end up needing to refactor some rather nasty patterns in this
series, so this isn't on you initially...

But since we're encountering this "reset_to_sane" pattern, can't we just
as easily fix it up with something more obvious than replacing an echo
to a specific ref with a tarring up and untarring of the whole .git each
time?

I.e. something like:

   # setup the .git initially

Then:

   test_when_finished "rm -rf copy" &&
   git clone . copy &&
   # munge the repo and use "git -C copy" for the tests"

?