Allow updating meta if new name exists but is deleted (#1053)

object.go

@@ -861,13 +861,13 @@ func (obs *obs) UpdateMeta(name string, meta *ObjectMeta) error {
 	// If the new name is different from the old, and it exists, error
 	// If there was an error that was not ErrObjectNotFound, error.
 	if name != meta.Name {
-		_, err = obs.GetInfo(meta.Name)
-		if err != ErrObjectNotFound {
-			if err == nil {
-				return ErrObjectAlreadyExists
-			}
+		existingInfo, err := obs.GetInfo(meta.Name)
+		if err != nil && !errors.Is(err, ErrObjectNotFound) {
 			return err
 		}
+		if err == nil && !existingInfo.Deleted {
+			return ErrObjectAlreadyExists
+		}
 	}
 
 	// Update Meta prevents update of ObjectMetaOptions (Link, ChunkSize)

test/object_test.go

@@ -391,6 +391,8 @@ func TestObjectMetadata(t *testing.T) {
 	// Simple with no Meta.
 	_, err = obs.PutString("A", "AAA")
 	expectOk(t, err)
+	_, err = obs.PutString("C", "CCC")
+	expectOk(t, err)
 
 	meta := &nats.ObjectMeta{Name: "A"}
 	meta.Description = "descA"
@@ -423,15 +425,25 @@ func TestObjectMetadata(t *testing.T) {
 
 	info, err = obs.GetInfo("B")
 	expectOk(t, err)
-
 	if info.Name != "B" || info.Description != "descB" || info.Headers == nil || info.Headers.Get("color") != "red" {
 		t.Fatalf("Update failed: %+v", info)
 	}
 
-	// delete the object to test updating against a deleted object
-	err = obs.Delete("B")
+	// Change meta name to existing object's name
+	meta = &nats.ObjectMeta{Name: "C"}
+
+	err = obs.UpdateMeta("B", meta)
+	expectErr(t, err, nats.ErrObjectAlreadyExists)
+
+	err = obs.Delete("C")
 	expectOk(t, err)
 	err = obs.UpdateMeta("B", meta)
+	expectOk(t, err)
+
+	// delete the object to test updating against a deleted object
+	err = obs.Delete("C")
+	expectOk(t, err)
+	err = obs.UpdateMeta("C", meta)
 	expectErr(t, err, nats.ErrUpdateMetaDeleted)
 
 	err = obs.UpdateMeta("X", meta)