Sane use of test_expect_failure

Originally, test_expect_failure was designed to be the opposite
of test_expect_success, but this was a bad decision.  Most tests
run a series of commands that leads to the single command that
needs to be tested, like this:

    test_expect_{success,failure} 'test title' '
	setup1 &&
        setup2 &&
        setup3 &&
        what is to be tested
    '

And expecting a failure exit from the whole sequence misses the
point of writing tests.  Your setup$N that are supposed to
succeed may have failed without even reaching what you are
trying to test.  The only valid use of test_expect_failure is to
check a trivial single command that is expected to fail, which
is a minority in tests of Porcelain-ish commands.

This large-ish patch rewrites all uses of test_expect_failure to
use test_expect_success and rewrites the condition of what is
tested, like this:

    test_expect_success 'test title' '
	setup1 &&
        setup2 &&
        setup3 &&
        ! this command should fail
    '

test_expect_failure is redefined to serve as a reminder that
that test *should* succeed but due to a known breakage in git it
currently does not pass.  So if git-foo command should create a
file 'bar' but you discovered a bug that it doesn't, you can
write a test like this:

    test_expect_failure 'git-foo should create bar' '
        rm -f bar &&
        git foo &&
        test -f bar
    '

This construct acts similar to test_expect_success, but instead
of reporting "ok/FAIL" like test_expect_success does, the
outcome is reported as "FIXED/still broken".

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/t/t6101-rev-parse-parents.sh b/t/t6101-rev-parse-parents.sh
index 0724864e56..2328b69947 100755
--- a/t/t6101-rev-parse-parents.sh
+++ b/t/t6101-rev-parse-parents.sh
@@ -26,7 +26,7 @@ test_expect_success 'final^1^1^1 = final^^^' "test $(git rev-parse final^1^1^1)
 test_expect_success 'final^1^2' "test $(git rev-parse start2) = $(git rev-parse final^1^2)"
 test_expect_success 'final^1^2 != final^1^1' "test $(git rev-parse final^1^2) != $(git rev-parse final^1^1)"
 test_expect_success 'final^1^3 not valid' "if git rev-parse --verify final^1^3; then false; else :; fi"
-test_expect_failure '--verify start2^1' 'git rev-parse --verify start2^1'
+test_expect_success '--verify start2^1' '! git rev-parse --verify start2^1'
 test_expect_success '--verify start2^0' 'git rev-parse --verify start2^0'
 
 test_expect_success 'repack for next test' 'git repack -a -d'