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, 6 insertions, 6 deletions

diff --git a/t/t6023-merge-file.sh b/t/t6023-merge-file.sh
index ae3b6f283..86419964b 100755
--- a/t/t6023-merge-file.sh
+++ b/t/t6023-merge-file.sh
@@ -66,8 +66,8 @@ test_expect_success "merge result added missing LF" \
 	"git diff test.txt test2.txt"
 
 cp test.txt backup.txt
-test_expect_failure "merge with conflicts" \
-	"git merge-file test.txt orig.txt new3.txt"
+test_expect_success "merge with conflicts" \
+	"! git merge-file test.txt orig.txt new3.txt"
 
 cat > expect.txt << EOF
 <<<<<<< test.txt
@@ -89,8 +89,8 @@ EOF
 test_expect_success "expected conflict markers" "git diff test.txt expect.txt"
 
 cp backup.txt test.txt
-test_expect_failure "merge with conflicts, using -L" \
-	"git merge-file -L 1 -L 2 test.txt orig.txt new3.txt"
+test_expect_success "merge with conflicts, using -L" \
+	"! git merge-file -L 1 -L 2 test.txt orig.txt new3.txt"
 
 cat > expect.txt << EOF
 <<<<<<< 1
@@ -113,8 +113,8 @@ test_expect_success "expected conflict markers, with -L" \
 	"git diff test.txt expect.txt"
 
 sed "s/ tu / TU /" < new1.txt > new5.txt
-test_expect_failure "conflict in removed tail" \
-	"git merge-file -p orig.txt new1.txt new5.txt > out"
+test_expect_success "conflict in removed tail" \
+	"! git merge-file -p orig.txt new1.txt new5.txt > out"
 
 cat > expect << EOF
 Dominus regit me,