Re: [PATCH v2 5/7] t0027: cache expected output files

["Torsten Bögershausen" <tboegi@web.de>]

On Mon, Nov 09, 2026 at 10:58:26AM +0100, Patrick Steinhardt wrote:
> In the preceding commit we have optimized one aspect of t0027 already.
> Another inefficiency is `compare_files ()` and `compare_ws_file ()`,
> which are both called more than a 1000 times.
> 
> These functions will repeatedly generate the same expected outcome even
> though there's only a small handful of input files that the expected
> outcome is computed from. Recomputing those every time is of course
> quite pointless.
> 
> Improve this by computing the expected outcome once, only, to reduce the
> number of spawned processes. This reduces the runtime by around 20-25%,
> and on Windows the runtime decreases from 480 to 380 seconds.
> 
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  t/t0027-auto-crlf.sh | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/t/t0027-auto-crlf.sh b/t/t0027-auto-crlf.sh
> index 504a7ea54bb..b021f0855a8 100755
> --- a/t/t0027-auto-crlf.sh
> +++ b/t/t0027-auto-crlf.sh
> @@ -5,22 +5,23 @@ test_description='CRLF conversion all combinations'
>  . ./test-lib.sh
>  
>  compare_files () {
> -	tr '\015\000' QN <"$1" >"$1".expect &&
> +	{ test -f "$1".expect || tr '\015\000' QN <"$1" >"$1".expect; } &&
>  	tr '\015\000' QN <"$2" | tr -d 'Z' >"$2".actual &&
> -	test_cmp "$1".expect "$2".actual &&
> -	rm "$1".expect "$2".actual
> +	test_cmp "$1".expect "$2".actual
>  }
>  

Nice.
If you want to save even more CPU/SSD-cycles,
you can prepare the expect files like this:
(No, I didn't do any benchmarks, nor look at ws_compare)


diff --git a/t/t0027-auto-crlf.sh b/t/t0027-auto-crlf.sh
index 49dbf09da7..3563336162 100755
--- a/t/t0027-auto-crlf.sh
+++ b/t/t0027-auto-crlf.sh
@@ -5,10 +5,9 @@ test_description='CRLF conversion all combinations'
 . ./test-lib.sh
 
 compare_files () {
-	tr '\015\000' QN <"$1" >"$1".expect &&
 	tr '\015\000' QN <"$2" | tr -d 'Z' >"$2".actual &&
-	test_cmp "$1".expect "$2".actual &&
-	rm "$1".expect "$2".actual
+	test_cmp "expd/$1".expect "$2".actual &&
+	rm "$2".actual
 }
 
 compare_ws_file () {
@@ -343,6 +342,25 @@ checkout_files () {
 	"
 }
 
+test_expect_success 'create expect files' '
+	printf "\$Id: 0000000000000000000000000000000000000000 \$\nLINEONE\nLINETWO\nLINETHREE"     >LF &&
+	printf "\$Id: 0000000000000000000000000000000000000000 \$\r\nLINEONE\r\nLINETWO\r\nLINETHREE" >CRLF &&
+	printf "\$Id: 0000000000000000000000000000000000000000 \$\nLINEONE\r\nLINETWO\nLINETHREE"   >CRLF_mix_LF &&
+	printf "\$Id: 0000000000000000000000000000000000000000 \$\nLINEONE\nLINETWO\rLINETHREE"     >LF_mix_CR &&
+	printf "\$Id: 0000000000000000000000000000000000000000 \$\r\nLINEONE\r\nLINETWO\rLINETHREE"   >CRLF_mix_CR &&
+	printf "\$Id: 0000000000000000000000000000000000000000 \$\r\nLINEONEQ\r\nLINETWO\r\nLINETHREE" | q_to_nul >CRLF_nul &&
+	printf "\$Id: 0000000000000000000000000000000000000000 \$\nLINEONEQ\nLINETWO\nLINETHREE" | q_to_nul >LF_nul &&
+  mkdir expd &&
+  echo "* -text" >expd/.gitattributes &&
+	tr "\015\000" QN <LF >expd/LF.expect &&
+	tr "\015\000" QN <CRLF >expd/CRLF.expect &&
+	tr "\015\000" QN <CRLF_mix_LF >expd/CRLF_mix_LF.expect &&
+	tr "\015\000" QN <LF_mix_CR >expd/LF_mix_CR.expect &&
+	tr "\015\000" QN <CRLF_mix_CR >expd/CRLF_mix_CR.expect &&
+	tr "\015\000" QN <CRLF_nul >expd/CRLF_nul.expect &&
+	tr "\015\000" QN <LF_nul >expd/LF_nul.expect
+  '
+
 # Test control characters
 # NUL SOH CR EOF==^Z
 test_expect_success 'ls-files --eol -o Text/Binary' '



[snip]