Mock gRPC Response Stream for unit testing - C#

Question

I have a function that calls a gRPC endpoint, converts the objects into POCO objects and returns them as a list.

public class ActionPlanConnectionsService : IConnectionService
    {
            #region Fields
    
            /// <summary>
            /// Grpc client
            /// </summary>
            private readonly ConnectionDb.ConnectionDbClient _client;
            #endregion
    
            public ActionPlanConnectionsService(ConnectionDb.ConnectionDbClient channel)
            {
                _client = channel;
            }
    
            public async Task<IEnumerable<Connection>> Get(int actionPlanId, int implementation)
            {
               List<Connection> diagramConnections = new List<Connection>();
               GetConnectionsByIdAndImplementationMessage message = new GetConnectionsByIdAndImplementationMessage
               {
                   ActionPlanId = actionPlanId,
                   Implementation = implementation
               };
    
               using var call = _client.GetAllConnections(message);
               await foreach (ConnectionServiceModel connection in call.ResponseStream.ReadAllAsync())
               {
                   // Never enters here as ResponseStream has no elements when unit testing!!
                   diagramConnections.Add(new Connection(
                       connection.FromActionPlanStepId, connection.ToActionPlanStepId, connection.ActionPlanId,
                       connection.Qualifier, connection.Implementation, connection.Path));
               }
    
               return diagramConnections;
           }
   }

I have been developing a unit test for this function but the list returned always has a count of zero. This is because the ResponseStream has no elements inside of it.

How can I mock the ResponseStream?

My unit test so far:

[Test]
        public async Task GetConnectionsTest()
        {
            // Arrange
            Mock<ConnectionDb.ConnectionDbClient> mockClient = new Mock<ConnectionDb.ConnectionDbClient>();
            Mock<IAsyncStreamReader<ConnectionServiceModel>> mockResponseStream
                = new Mock<IAsyncStreamReader<ConnectionServiceModel>>();

            List<ConnectionServiceModel> connectionServiceModels =
                new List<ConnectionServiceModel>
                {
                    new ConnectionServiceModel
                    {
                        ActionPlanId = 1,
                        FromActionPlanStepId = 1,
                        ToActionPlanStepId = 1,
                        Implementation = 0,
                        Qualifier = 1,
                        Path = " 1;2;3;4;5;6;7;8;9;10;11;12;13;14"
                    }
                };

            var fakeCall = TestCalls.AsyncServerStreamingCall
                (mockResponseStream.Object,
                Task.FromResult(new Metadata()), () => Status.DefaultSuccess,
                () => new Metadata(), () => { });

            mockClient.Setup(m => m.GetAllConnections(
                It.IsAny<GetConnectionsByIdAndImplementationMessage>(),
                null, null, CancellationToken.None)).Returns(fakeCall);

            // Act
            ActionPlanConnectionsService service = new ActionPlanConnectionsService(mockClient.Object);
            IEnumerable<Connection> connections = await service.Get(1, 1);

            // Assert
            
            // CONNECTIONS WILL ALWAYS HAVE 0 Elements as the response isn't setup for it.
        }
    }

question from:https://stackoverflow.com/questions/65917871/mock-grpc-response-stream-for-unit-testing-c-sharp

Answer 1

Waitting for answers

Answer 2

One possible solution here may be to use mock.qa and mock the entire service with fake data from `.json` files.

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