feat: nil signer

signature/google/signer.go

@@ -23,7 +23,6 @@ type KeyManagementClient interface {
 	AsymmetricSign(context.Context, *kmspb.AsymmetricSignRequest, ...gax.CallOption) (*kmspb.AsymmetricSignResponse, error)
 }
 
-// Signer is a Google Cloud KMS signer.
 type signer struct {
 	client  KeyManagementClient
 	keyName string

signature/local/signer.go

@@ -0,0 +1,15 @@
+package local
+
+import "context"
+
+type nilSigner struct{}
+
+// NewNilSigner creates a signer that does nothing.
+func NewNilSigner() *nilSigner {
+	return &nilSigner{}
+}
+
+// Sign returns the same message and no error.
+func (s *nilSigner) Sign(ctx context.Context, message []byte) ([]byte, error) {
+	return message, nil
+}

signature/local/signer_test.go

@@ -0,0 +1,17 @@
+package local_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/brokeyourbike/clearbank-api-client-go/signature/local"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNilSigner(t *testing.T) {
+	signer := local.NewNilSigner()
+	got, err := signer.Sign(context.TODO(), []byte("hello!"))
+
+	assert.NoError(t, err)
+	assert.Equal(t, []byte("hello!"), got)
+}