Re: [PATCH 2/2] test-lib: teach test_seq the -f option

> The "seq" tool has a "-f" option to produce printf-style formatted
> lines. Let's teach our test_seq helper the same trick. This lets us get
> rid of some shell loops in test snippets (which are particularly verbose
> in our test suite because we have to "|| return 1" to keep the &&-chain
> going).
> 
> This converts a few call-sites I found by grepping around the test
> suite. A few notes on these:
> 
>   - In "seq", the format specifier is a "%g" float. Since test_seq only
>     supports integers, I've kept the more natural "%d" (which is what
>     these call sites were using already).

>   - Like "seq", test_seq automatically adds a newline to the specified
>     format. This is what all callers are doing already except for t0021,
>     but there we do not care about the exact format. We are just trying
>     to printf a large number of bytes to a file. It's not worth
>     complicating other callers or adding an option to avoid the newline
>     in that caller.
> 
>   - Most conversions are just replacing a shell loop (which does get rid
>     of an extra fork, since $() requires a subshell). In t0612 we can
>     replace an awk invocation, which I think makes the end result more
>     readable, as there's less quoting.
> 
>   - In t7422 we can replace one loop, but sadly we have to leave the
>     loop directly above it. This is because that earlier loop wants to
>     include the seq value twice in the output, which test_seq does not
>     support (nor does regular seq). If you run:
> 
>       test_seq -f "foo-%d %d" 10
> 
>     the second "%d" will always be the empty string. You might naively
>     think that test_seq could add some extra arguments, like:
> 
>       # 3 ought to be enough for anyone...
>       printf "$fmt\n" "$i "$i" $i"
> 
>     but that just triggers printf to format multiple lines, one per
>     extra set of arguments.
> 
>     So we'd have to actually parse the format string, figure out how
>     many "%" placeholders are there, and then feed it that many
>     instances of the sequence number. The complexity isn't worth it.
> 
> Signed-off-by: Jeff King <peff@peff.net>
> ---
>  t/t0021-conversion.sh                  |  4 ++--
>  t/t0610-reftable-basics.sh             |  6 +-----
>  t/t0612-reftable-jgit-compatibility.sh | 13 +++++--------
>  t/t0613-reftable-write-options.sh      | 24 ++++--------------------
>  t/t1400-update-ref.sh                  | 10 ++--------
>  t/t5004-archive-corner-cases.sh        |  5 +----
>  t/t6422-merge-rename-corner-cases.sh   | 10 ++--------
>  t/t7422-submodule-output.sh            |  6 +-----
>  t/test-lib-functions.sh                |  9 ++++++++-
>  9 files changed, 26 insertions(+), 61 deletions(-)
> 
> diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
> index bf10d253ec..f0d50d769e 100755
> --- a/t/t0021-conversion.sh
> +++ b/t/t0021-conversion.sh
> @@ -281,7 +281,7 @@ test_expect_success 'required filter with absent smudge field' '
>  test_expect_success 'filtering large input to small output should use little memory' '
>  	test_config filter.devnull.clean "cat >/dev/null" &&
>  	test_config filter.devnull.required true &&
> -	for i in $(test_seq 1 30); do printf "%1048576d" 1 || return 1; done >30MB &&
> +	test_seq -f "%1048576d" 1 30 >30MB &&

> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
> index bee4a2ca34..8c176f4efc 100644
> --- a/t/test-lib-functions.sh
> +++ b/t/test-lib-functions.sh
> @@ -1454,6 +1454,13 @@ test_cmp_fspath () {
>  # from 1.
>  
>  test_seq () {
> +	local fmt="%d"
> +	case "$1" in
> +	-f)
> +		fmt="$2"

> +		shift 2
> +		;;
> +	esac
>  	case $# in
>  	1)	set 1 "$@" ;;
>  	2)	;;
> @@ -1462,7 +1469,7 @@ test_seq () {
>  	test_seq_counter__=$1
>  	while test "$test_seq_counter__" -le "$2"
>  	do
> -		echo "$test_seq_counter__"
> +		printf "$fmt\n" "$test_seq_counter__"

>  		test_seq_counter__=$(( $test_seq_counter__ + 1 ))
>  	done
>  }
> -- 
> 2.50.0.385.g2a828bf5b7
>