Migrate writeref from using the ruby implementation to go

2 files changed, 14 insertions, 3 deletions

diff --git a/internal/git/updateref/updateref.go b/internal/git/updateref/updateref.go
index c61cc7e62..01376be52 100644
--- a/internal/git/updateref/updateref.go
+++ b/internal/git/updateref/updateref.go
@@ -40,8 +40,8 @@ func (u *Updater) Create(ref, value string) error {
 
 // Update commands the reference to be updated to point at the sha specified in
 // newvalue
-func (u *Updater) Update(ref, newvalue string) error {
-	_, err := fmt.Fprintf(u.cmd, "update %s\x00%s\x00\x00", ref, newvalue)
+func (u *Updater) Update(ref, newvalue, oldvalue string) error {
+	_, err := fmt.Fprintf(u.cmd, "update %s\x00%s\x00%s\x00", ref, newvalue, oldvalue)
 	return err
 }
 
diff --git a/internal/git/updateref/updateref_test.go b/internal/git/updateref/updateref_test.go
index 1fb9aefb8..3de350b25 100644
--- a/internal/git/updateref/updateref_test.go
+++ b/internal/git/updateref/updateref_test.go
@@ -66,7 +66,7 @@ func TestUpdate(t *testing.T) {
 	require.NotNil(t, commit, "%s does not exist in the test repository", ref)
 	require.NotEqual(t, commit.Id, sha, "%s points to HEAD: %s in the test repository", ref, sha)
 
-	require.NoError(t, updater.Update(ref, sha))
+	require.NoError(t, updater.Update(ref, sha, ""))
 	require.NoError(t, updater.Wait())
 
 	// check the ref was updated
@@ -74,6 +74,17 @@ func TestUpdate(t *testing.T) {
 	require.NoError(t, logErr)
 	require.NotNil(t, commit)
 	require.Equal(t, commit.Id, sha, "reference was not updated")
+
+	// since ref has been updated to HEAD, we know that it does not point to HEAD^. So, HEAD^ is an invalid "old value" for updating ref
+	parentCommit, err := log.GetCommit(ctx, testRepo, "HEAD^")
+	require.NoError(t, err)
+	require.Error(t, updater.Update(ref, parentCommit.Id, parentCommit.Id))
+
+	// check the ref was not updated
+	commit, logErr = log.GetCommit(ctx, testRepo, ref)
+	require.NoError(t, logErr)
+	require.NotNil(t, commit)
+	require.NotEqual(t, commit.Id, parentCommit.Id, "reference was updated when it shouldn't have been")
 }
 
 func TestDelete(t *testing.T) {