Re: [PATCH 2/3] checkout: show bug about failed entries being included in final report

> After checkout, git usually reports how many entries were updated at
> that operation. However, because we count the entries too soon during
> the checkout process, we may actually include entries that do not get
> properly checked out in the end. This can lead to an inaccurate final
> report if the user expects it to show only the *successful* updates.
> This will be fixed in the next commit, but for now let's document it
> with a test that cover all checkout modes.
>
> Note that `test_checkout_workers` have to be slightly adjusted in order
> to use the construct `test_checkout_workers ...  test_must_fail git
> checkout`. The function runs the command given to it with an assignment
> prefix to set the GIT_TRACE2 variable. However, this this assignment has
> an undefined behavior when the command is a shell function (like
> `test_must_fail`). As POSIX specifies:
>
>   If the command name is a function that is not a standard utility
>   implemented as a function, variable assignments shall affect the
>   current execution environment during the execution of the function. It
>   is unspecified:
>
>     - Whether or not the variable assignments persist after the
>       completion of the function
>
>     - Whether or not the variables gain the export attribute during the
>       execution of the function
>
> Thus, in order to make sure the GIT_TRACE2 value gets visible to the git
> command executed by `test_must_fail`, export the variable and run git in
> a subshell.
>
> [1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
>      (Section 2.9.1: Simple Commands)
>
> Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
> ---
>  t/lib-parallel-checkout.sh          |  6 +++-
>  t/t2080-parallel-checkout-basics.sh | 50 +++++++++++++++++++++++++++++
>  2 files changed, 55 insertions(+), 1 deletion(-)
>
> diff --git a/t/lib-parallel-checkout.sh b/t/lib-parallel-checkout.sh
> index 83b279a846..acaee9cbb6 100644
> --- a/t/lib-parallel-checkout.sh
> +++ b/t/lib-parallel-checkout.sh
> @@ -25,7 +25,11 @@ test_checkout_workers () {
>  
>  	local trace_file=trace-test-checkout-workers &&
>  	rm -f "$trace_file" &&
> -	GIT_TRACE2="$(pwd)/$trace_file" "$@" 2>&8 &&
> +	(
> +		GIT_TRACE2="$(pwd)/$trace_file" &&
> +		export GIT_TRACE2 &&
> +		"$@" 2>&8
> +	) &&
>  
>  	local workers="$(grep "child_start\[..*\] git checkout--worker" "$trace_file" | wc -l)" &&
>  	test $workers -eq $expected_workers &&
> diff --git a/t/t2080-parallel-checkout-basics.sh b/t/t2080-parallel-checkout-basics.sh
> index 3e0f8c675f..6fd7e4c4b2 100755
> --- a/t/t2080-parallel-checkout-basics.sh
> +++ b/t/t2080-parallel-checkout-basics.sh
> @@ -226,4 +226,54 @@ test_expect_success SYMLINKS 'parallel checkout checks for symlinks in leading d
>  	)
>  '
>  
> +# This test is here (and not in e.g. t2022-checkout-paths.sh), because we
> +# check the final report including sequential, parallel, and delayed entries
> +# all at the same time. So we must have finer control of the parallel checkout
> +# variables.
> +test_expect_failure PERL '"git checkout ." report should not include failed entries' '
> +	write_script rot13-filter.pl "$PERL_PATH" \
> +		<"$TEST_DIRECTORY"/t0021/rot13-filter.pl &&
> +
> +	test_config_global filter.delay.process \
> +		"\"$(pwd)/rot13-filter.pl\" --always-delay delayed.log clean smudge delay" &&
> +	test_config_global filter.delay.required true &&
> +	test_config_global filter.cat.clean cat  &&
> +	test_config_global filter.cat.smudge cat  &&
> +	test_config_global filter.cat.required true  &&
> +
> +	set_checkout_config 2 0 &&
> +	git init failed_entries &&
> +	(
> +		cd failed_entries &&
> +		cat >.gitattributes <<-EOF &&
> +		*delay*              filter=delay
> +		parallel-ineligible* filter=cat
> +		EOF
> +		echo a >missing-delay.a &&
> +		echo a >parallel-ineligible.a &&
> +		echo a >parallel-eligible.a &&
> +		echo b >success-delay.b &&
> +		echo b >parallel-ineligible.b &&
> +		echo b >parallel-eligible.b &&
> +		git add -A &&
> +		git commit -m files &&
> +
> +		a_blob="$(git rev-parse :parallel-ineligible.a)" &&
> +		dir="$(echo "$a_blob" | cut -c 1-2)" &&
> +		file="$(echo "$a_blob" | cut -c 3-)" &&

> +		rm ".git/objects/$dir/$file" &&
> +		rm *.a *.b &&
> +
> +		test_checkout_workers 2 test_must_fail git checkout . 2>err &&
> +
> +		# All *.b entries should succeed and all *.a entries should fail:
> +		#  - missing-delay.a: the delay filter will drop this path
> +		#  - parallel-*.a: the blob will be missing
> +		#
> +		grep "Updated 3 paths from the index" err &&
> +		test "$(ls *.b | wc -l)" -eq 3 &&
> +		test "$(ls *.a | wc -l)" -eq 0