Hi Dscho On 12/11/2022 22:07, Johannes Schindelin via GitGitGadget wrote:
From: Johannes Schindelin <johannes.schindelin@xxxxxx> It is more performant to run `git diff --no-index` than running the `mingw_test_cmp` code with MSYS2's Bash, i.e. the Bash that Git for Windows uses. And a lot more readable.
This makes me wonder about the implications for our diff tests. We have ~200 calls to `test_cmp` in t*-diff-*.sh. I had a look at t4053-diff-no-index.sh and non of the tests that use `test_cmp` look critical for functionality that is used by `test_cmp` and there are tests for the exit code. I suspect that if `diff --no-index` breaks we'll end up with confusing test failures rather than misleading passes.
A side effect of this change is that on windows `test_cmp` will now except directories as well as files but I don't think that matters.
Note: Earlier attempts at fixing this involved a test helper that avoids the overhead of the diff machinery, in favor of implementing a behavior that is more in line with what `mingw_test_cmp` does now, but that attempt saw a lot of backlash and distractions during review and was therefore abandoned.
Hopefully most of the files we feed into `test_cmp` are small enough that the absolute difference in run-time is not too big. There is an optimization for -U0 that trims the common tail from the files before calling xdl_diff() but that does not help here because we need to use --ignore-cr-at-eol (otherwise `git diff --no-index -U0 || git diff --no-index` might speed up the common case of matching files).
Best Wishes Phillip
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx> --- t/test-lib-functions.sh | 66 ----------------------------------------- t/test-lib.sh | 2 +- 2 files changed, 1 insertion(+), 67 deletions(-) diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh index 8c44856eaec..452fe9bc8aa 100644 --- a/t/test-lib-functions.sh +++ b/t/test-lib-functions.sh @@ -1541,72 +1541,6 @@ test_skip_or_die () { error "$2" }-# The following mingw_* functions obey POSIX shell syntax, but are actually-# bash scripts, and are meant to be used only with bash on Windows. - -# A test_cmp function that treats LF and CRLF equal and avoids to fork -# diff when possible. -mingw_test_cmp () { - # Read text into shell variables and compare them. If the results - # are different, use regular diff to report the difference. - local test_cmp_a= test_cmp_b= - - # When text came from stdin (one argument is '-') we must feed it - # to diff. - local stdin_for_diff= - - # Since it is difficult to detect the difference between an - # empty input file and a failure to read the files, we go straight - # to diff if one of the inputs is empty. - if test -s "$1" && test -s "$2" - then - # regular case: both files non-empty - mingw_read_file_strip_cr_ test_cmp_a <"$1" - mingw_read_file_strip_cr_ test_cmp_b <"$2" - elif test -s "$1" && test "$2" = - - then - # read 2nd file from stdin - mingw_read_file_strip_cr_ test_cmp_a <"$1" - mingw_read_file_strip_cr_ test_cmp_b - stdin_for_diff='<<<"$test_cmp_b"' - elif test "$1" = - && test -s "$2" - then - # read 1st file from stdin - mingw_read_file_strip_cr_ test_cmp_a - mingw_read_file_strip_cr_ test_cmp_b <"$2" - stdin_for_diff='<<<"$test_cmp_a"' - fi - test -n "$test_cmp_a" && - test -n "$test_cmp_b" && - test "$test_cmp_a" = "$test_cmp_b" || - eval "diff -u \"\$@\" $stdin_for_diff" -} - -# $1 is the name of the shell variable to fill in -mingw_read_file_strip_cr_ () { - # Read line-wise using LF as the line separator - # and use IFS to strip CR. - local line - while : - do - if IFS=$'\r' read -r -d $'\n' line - then - # good - line=$line$'\n' - else - # we get here at EOF, but also if the last line - # was not terminated by LF; in the latter case, - # some text was read - if test -z "$line" - then - # EOF, really - break - fi - fi - eval "$1=\$$1\$line" - done -} - # Like "env FOO=BAR some-program", but run inside a subshell, which means # it also works for shell functions (though those functions cannot impact # the environment outside of the test_env invocation). diff --git a/t/test-lib.sh b/t/test-lib.sh index 7726d1da88a..f8c6205e08f 100644 --- a/t/test-lib.sh +++ b/t/test-lib.sh @@ -1546,7 +1546,7 @@ case $uname_s in test_set_prereq SED_STRIPS_CR test_set_prereq GREP_STRIPS_CR test_set_prereq WINDOWS - GIT_TEST_CMP=mingw_test_cmp + GIT_TEST_CMP="GIT_DIR=/dev/null git diff --no-index --ignore-cr-at-eol --" ;; *CYGWIN*) test_set_prereq POSIXPERM
