update-ref and tag: add --create-reflog arg

Allow the creation of a ref (e.g. stash) with a reflog already in
place. For most refs (e.g. those under refs/heads), this happens
automatically, but for others, we need this option.

Currently, git does this by pre-creating the reflog, but alternate ref
backends might store reflogs somewhere other than .git/logs.  Code
that now directly manipulates .git/logs should instead use git
plumbing commands.

I also added --create-reflog to git tag, just for completeness.

In a moment, we will use this argument to make git stash work with
alternate ref backends.

Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 51 insertions, 1 deletions

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index d787bf50f..9d21c1927 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -23,6 +23,7 @@ test_expect_success setup '
 m=refs/heads/master
 n_dir=refs/heads/gu
 n=$n_dir/fixes
+outside=foo
 
 test_expect_success \
 	"create $m" \
@@ -74,6 +75,24 @@ test_expect_success "delete $m (by HEAD)" '
 '
 rm -f .git/$m
 
+test_expect_success 'update-ref does not create reflogs by default' '
+	test_when_finished "git update-ref -d $outside" &&
+	git update-ref $outside $A &&
+	git rev-parse $A >expect &&
+	git rev-parse $outside >actual &&
+	test_cmp expect actual &&
+	test_must_fail git reflog exists $outside
+'
+
+test_expect_success 'update-ref creates reflogs with --create-reflog' '
+	test_when_finished "git update-ref -d $outside" &&
+	git update-ref --create-reflog $outside $A &&
+	git rev-parse $A >expect &&
+	git rev-parse $outside >actual &&
+	test_cmp expect actual &&
+	git reflog exists $outside
+'
+
 test_expect_success \
 	"create $m (by HEAD)" \
 	"git update-ref HEAD $A &&
@@ -472,6 +491,25 @@ test_expect_success 'stdin create ref works' '
 	test_cmp expect actual
 '
 
+test_expect_success 'stdin does not create reflogs by default' '
+	test_when_finished "git update-ref -d $outside" &&
+	echo "create $outside $m" >stdin &&
+	git update-ref --stdin <stdin &&
+	git rev-parse $m >expect &&
+	git rev-parse $outside >actual &&
+	test_cmp expect actual &&
+	test_must_fail git reflog exists $outside
+'
+
+test_expect_success 'stdin creates reflogs with --create-reflog' '
+	echo "create $outside $m" >stdin &&
+	git update-ref --create-reflog --stdin <stdin &&
+	git rev-parse $m >expect &&
+	git rev-parse $outside >actual &&
+	test_cmp expect actual &&
+	git reflog exists $outside
+'
+
 test_expect_success 'stdin succeeds with quoted argument' '
 	git update-ref -d $a &&
 	echo "create $a \"$m\"" >stdin &&
diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index d1ff5c94f..d31788cc6 100755
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -51,7 +51,19 @@ test_expect_success 'creating a tag using default HEAD should succeed' '
 	echo foo >foo &&
 	git add foo &&
 	git commit -m Foo &&
-	git tag mytag
+	git tag mytag &&
+	test_must_fail git reflog exists refs/tags/mytag
+'
+
+test_expect_success 'creating a tag with --create-reflog should create reflog' '
+	test_when_finished "git tag -d tag_with_reflog" &&
+	git tag --create-reflog tag_with_reflog &&
+	git reflog exists refs/tags/tag_with_reflog
+'
+
+test_expect_success '--create-reflog does not create reflog on failure' '
+	test_must_fail git tag --create-reflog mytag &&
+	test_must_fail git reflog exists refs/tags/mytag
 '
 
 test_expect_success 'listing all tags if one exists should succeed' '