Check for empty change request

internal/dnsx/register.go

@@ -36,6 +36,7 @@ func NewManager(s dnsiface.Service, project, zone string) *Manager {
 
 // Register creates a new resource record for hostname with the given ipv4 and ipv6 adresses.
 func (d *Manager) Register(ctx context.Context, hostname, ipv4, ipv6 string) (*dns.Change, error) {
+	var err error
 	chg := &dns.Change{}
 	records := []struct {
 		ip    string
@@ -49,7 +50,8 @@ func (d *Manager) Register(ctx context.Context, hostname, ipv4, ipv6 string) (*d
 		if record.ip == "" {
 			continue
 		}
-		rr, err := d.get(ctx, hostname, record.rtype)
+		var rr *dns.ResourceRecordSet
+		rr, err = d.get(ctx, hostname, record.rtype)
 		if rr != nil {
 			// Found a registration.
 			if len(rr.Rrdatas) == 1 && rr.Rrdatas[0] == record.ip {
@@ -82,6 +84,10 @@ func (d *Manager) Register(ctx context.Context, hostname, ipv4, ipv6 string) (*d
 			)
 		}
 	}
+	if chg.Additions == nil && chg.Deletions == nil {
+		// Without any actions, the ChangeCreate will fail with an error.
+		return nil, err
+	}
 	// Apply changes.
 	result, err := d.Service.ChangeCreate(ctx, d.Project, d.Zone, chg)
 	if err != nil {

internal/dnsx/register_test.go

@@ -29,6 +29,9 @@ func (f *fakeDNS) ResourceRecordSetsGet(ctx context.Context, project string, zon
 }
 
 func (f *fakeDNS) ChangeCreate(ctx context.Context, project string, zone string, change *dns.Change) (*dns.Change, error) {
+	if change.Additions == nil && change.Deletions == nil {
+		return nil, errors.New("fake change create error")
+	}
 	return change, f.chgErr
 }