test: add unit test

Signed-off-by: Junjie Gao <junjiegao@microsoft.com>

Author: JeyJeyGao

internal/mock/mocks.go

@@ -125,6 +125,7 @@ type Repository struct {
 	FetchSignatureBlobError    error
 	MissMatchDigest            bool
 	ExceededNumOfSignatures    bool
+	PushSignatureError         error
 }
 
 func NewRepository() Repository {
@@ -163,6 +164,10 @@ func (t Repository) FetchSignatureBlob(ctx context.Context, desc ocispec.Descrip
 }
 
 func (t Repository) PushSignature(ctx context.Context, mediaType string, blob []byte, subject ocispec.Descriptor, annotations map[string]string) (blobDesc, manifestDesc ocispec.Descriptor, err error) {
+	if t.PushSignatureError != nil {
+		return ocispec.Descriptor{}, ocispec.Descriptor{}, t.PushSignatureError
+	}
+
 	return ocispec.Descriptor{}, ocispec.Descriptor{}, nil
 }
 

notation_test.go

@@ -155,6 +155,19 @@ func TestSignSuccessWithUserMetadata(t *testing.T) {
 	}
 }
 
+func TestSignWithDanglingReferrersIndex(t *testing.T) {
+	repo := mock.NewRepository()
+	repo.PushSignatureError = errors.New("failed to delete dangling referrers index")
+	opts := SignOptions{}
+	opts.ArtifactReference = mock.SampleArtifactUri
+	opts.SignatureMediaType = jws.MediaTypeEnvelope
+
+	_, err := Sign(context.Background(), &dummySigner{}, repo, opts)
+	if err == nil {
+		t.Fatalf("no error occurred, expected error: failed to delete dangling referrers index")
+	}
+}
+
 func TestSignWithInvalidExpiry(t *testing.T) {
 	repo := mock.NewRepository()
 	testCases := []struct {