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git-bisect: allow bisecting with only one bad commit.
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This allows you to say:

	git bisect start
	git bisect bad $bad
	git bisect next

to start bisection without knowing a good commit.  This would
have you try a commit that is half-way since the beginning of
the history, which is rather wasteful if you already know a good
commit, but if you don't (or your history is short enough that
you do not care), there is no reason not to allow this.

Signed-off-by: Junio C Hamano <junkio@cox.net>
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Junio C Hamano committed Apr 7, 2007
1 parent 4f50671 commit 0a5280a
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Showing 2 changed files with 59 additions and 45 deletions.
87 changes: 53 additions & 34 deletions git-bisect.sh
Original file line number Diff line number Diff line change
Expand Up @@ -168,26 +168,40 @@ bisect_write_good() {
}

bisect_next_check() {
next_ok=no
git show-ref -q --verify refs/bisect/bad &&
test -n "$(git for-each-ref "refs/bisect/good-*")" &&
next_ok=yes

case "$next_ok,$1" in
no,) false ;;
no,fail)
THEN=''
test -d "$GIT_DIR/refs/bisect" || {
echo >&2 'You need to start by "git bisect start".'
THEN='then '
}
echo >&2 'You '$THEN'need to give me at least one good' \
'and one bad revisions.'
echo >&2 '(You can use "git bisect bad" and' \
'"git bisect good" for that.)'
exit 1 ;;
missing_good= missing_bad=
git show-ref -q --verify refs/bisect/bad || missing_bad=t
test -n "$(git for-each-ref "refs/bisect/good-*")" || missing_good=t

case "$missing_good,$missing_bad,$1" in
,,*)
: have both good and bad - ok
;;
*,)
# do not have both but not asked to fail - just report.
false
;;
t,,good)
# have bad but not good. we could bisect although
# this is less optimum.
echo >&2 'Warning: bisecting only with a bad commit.'
if test -t 0
then
printf >&2 'Are you sure [Y/n]? '
case "$(read yesno)" in [Nn]*) exit 1 ;; esac
fi
: bisect without good...
;;
*)
true ;;
THEN=''
test -d "$GIT_DIR/refs/bisect" || {
echo >&2 'You need to start by "git bisect start".'
THEN='then '
}
echo >&2 'You '$THEN'need to give me at least one good' \
'and one bad revisions.'
echo >&2 '(You can use "git bisect bad" and' \
'"git bisect good" for that.)'
exit 1 ;;
esac
}

Expand All @@ -198,27 +212,32 @@ bisect_auto_next() {
bisect_next() {
case "$#" in 0) ;; *) usage ;; esac
bisect_autostart
bisect_next_check fail
bisect_next_check good

bad=$(git-rev-parse --verify refs/bisect/bad) &&
good=$(git-rev-parse --sq --revs-only --not \
$(cd "$GIT_DIR" && ls refs/bisect/good-*)) &&
rev=$(eval "git-rev-list --bisect $good $bad -- $(cat "$GIT_DIR/BISECT_NAMES")") || exit
if [ -z "$rev" ]; then
echo "$bad was both good and bad"
exit 1
good=$(git for-each-ref --format='^%(objectname)' \
"refs/bisect/good-*" | tr '[\012]' ' ') &&
eval="git-rev-list --bisect-vars $good $bad --" &&
eval="$eval $(cat "$GIT_DIR/BISECT_NAMES")" &&
eval=$(eval "$eval") &&
eval "$eval" || exit

if [ -z "$bisect_rev" ]; then
echo "$bad was both good and bad"
exit 1
fi
if [ "$rev" = "$bad" ]; then
echo "$rev is first bad commit"
git-diff-tree --pretty $rev
exit 0
if [ "$bisect_rev" = "$bad" ]; then
echo "$bisect_rev is first bad commit"
git-diff-tree --pretty $bisect_rev
exit 0
fi
nr=$(eval "git-rev-list $rev $good -- $(cat $GIT_DIR/BISECT_NAMES)" | wc -l) || exit
echo "Bisecting: $nr revisions left to test after this"
echo "$rev" > "$GIT_DIR/refs/heads/new-bisect"

echo "Bisecting: $bisect_nr revisions left to test after this"
echo "$bisect_rev" >"$GIT_DIR/refs/heads/new-bisect"
git checkout -q new-bisect || exit
mv "$GIT_DIR/refs/heads/new-bisect" "$GIT_DIR/refs/heads/bisect" &&
GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD refs/heads/bisect
git-show-branch "$rev"
git-show-branch "$bisect_rev"
}

bisect_visualize() {
Expand Down
17 changes: 6 additions & 11 deletions t/t6030-bisect-run.sh
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@
#
test_description='Tests git-bisect functionality'

exec </dev/null

. ./test-lib.sh

add_line_into_file()
Expand Down Expand Up @@ -37,21 +39,14 @@ test_expect_success \
HASH3=$(git rev-list HEAD | head -2 | tail -1) &&
HASH4=$(git rev-list HEAD | head -1)'

test_expect_success 'bisect does not start with only one bad' '
test_expect_success 'bisect starts with only one bad' '
git bisect reset &&
git bisect start &&
git bisect bad $HASH4 || return 1
if git bisect next
then
echo Oops, should have failed.
false
else
:
fi
git bisect bad $HASH4 &&
git bisect next
'

test_expect_success 'bisect does not start with only one good' '
test_expect_success 'bisect starts with only one good' '
git bisect reset &&
git bisect start &&
git bisect good $HASH1 || return 1
Expand Down

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