test: caution on our version of 'yes'

During a review of a patch, we noticed that we use our own imitation of 'yes' with the limit of 99 lines. It is very tempting to lift this arbitrary limit, but the limit is there for a reason. Add an in-code comment to prevent future developers from wasting their time. Signed-off-by: Junio C Hamano <gitster@pobox.com>

Junio C Hamano committed Feb 9, 2019 at 10:25 UTC 11f470aee7ccd43bc2be159e69e121c35a72f91d
2 files changed +14 -1
t/README
+9
@@ -927,6 +927,15 @@ library for your script to use.
927 test_oid_init or test_oid_cache. Providing an unknown key is an
928 error.
929
930 + - yes [<string>]
931 +
932 + This is often seen in modern UNIX but some platforms lack it, so
933 + the test harness overrides the platform implementation with a
934 + more limited one. Use this only when feeding a handful lines of
935 + output to the downstream---unlike the real version, it generates
936 + only up to 99 lines.
937 +
938 +
939 Prerequisites
940 -------------
941
t/test-lib.sh
+5 -1
@@ -1313,7 +1313,11 @@ then
1313 fi
1314 fi
1315
1316 -# Provide an implementation of the 'yes' utility
1316 +# Provide an implementation of the 'yes' utility; the upper bound
1317 +# limit is there to help Windows that cannot stop this loop from
1318 +# wasting cycles when the downstream stops reading, so do not be
1319 +# tempted to turn it into an infinite loop. cf. 6129c930 ("test-lib:
1320 +# limit the output of the yes utility", 2016-02-02)
1321 yes () {
1322 if test $# = 0
1323 then