Addded a validation test.

pkg/service/operation/storage/storage.go

@@ -38,7 +38,7 @@ type Storage interface {
 	CancelOperation(id string) (*StoredOperation, error)
 }
 
-// StatusObjectID attempts to parse the submission id from the StatusObjectID of the operation. This is done by taking the last word
+// StatusObjectID attempts to parse the submission id from the ID of the operation. This is done by taking the last word
 // that results from splitting the id by "/". On failures, the empty string is returned.
 func StatusObjectID(opID string) string {
 	i := strings.LastIndex(opID, "/")

pkg/service/operation/storage_test.go

@@ -8,7 +8,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/stretchr/testify/require"
-	storage2 "github.com/tbd54566975/ssi-service/pkg/service/manifest/storage"
+	manifeststg "github.com/tbd54566975/ssi-service/pkg/service/manifest/storage"
 	"github.com/tbd54566975/ssi-service/pkg/service/operation/credential"
 	opstorage "github.com/tbd54566975/ssi-service/pkg/service/operation/storage"
 	"github.com/tbd54566975/ssi-service/pkg/service/operation/storage/namespace"
@@ -31,15 +31,9 @@ func setupTestDB(t *testing.T) storage.ServiceStorage {
 
 func TestStorage_CancelOperation(t *testing.T) {
 	s := setupTestDB(t)
-	data, err := json.Marshal(storage2.StoredApplication{})
+	data, err := json.Marshal(manifeststg.StoredApplication{})
 	require.NoError(t, err)
 	require.NoError(t, s.Write(credential.ApplicationNamespace, "hello", data))
-	opData, err := json.Marshal(opstorage.StoredOperation{
-		ID:   "credentials/responses/hello",
-		Done: false,
-	})
-	require.NoError(t, err)
-	require.NoError(t, s.Write(namespace.FromParent("credentials/responses"), "credentials/responses/hello", opData))
 
 	type fields struct {
 		db storage.ServiceStorage
@@ -53,6 +47,7 @@ func TestStorage_CancelOperation(t *testing.T) {
 		args    args
 		want    *opstorage.StoredOperation
 		wantErr bool
+		done    bool
 	}{
 		{
 			name: "bad id returns error",
@@ -77,9 +72,28 @@ func TestStorage_CancelOperation(t *testing.T) {
 				Done: true,
 			},
 		},
+		{
+			name: "done operation returns error on cancellation",
+			done: true,
+			fields: fields{
+				db: s,
+			},
+			args: args{
+				id: "credentials/responses/hello",
+			},
+			wantErr: true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+
+			opData, err := json.Marshal(opstorage.StoredOperation{
+				ID:   "credentials/responses/hello",
+				Done: tt.done,
+			})
+			require.NoError(t, err)
+			require.NoError(t, s.Write(namespace.FromParent("credentials/responses"), "credentials/responses/hello", opData))
+
 			b := Storage{
 				db: tt.fields.db,
 			}