How do I mock AddAsync?

Question

I'm writing unit test. For testing the method below,

public async Task<Guid> CreateWebJobStatus(string blobId, Guid loggedInUserId, string loggedInUserEmail) {

    Guid webJobStatusId = Guid.NewGuid();

    WebJobStatus newWebJobStatus = new WebJobStatus
    {
        WorkJobStatusId = webJobStatusId,
        TransactionId = Guid.NewGuid(),
        Status = (int)WebJobStatusEnum.PENDING,
        BlobId = blobId,
        UserId = loggedInUserId,
        UserEmail = loggedInUserEmail,
    };
    await _dbContext.WebJobStatus.AddAsync(newWebJobStatus);
    await _dbContext.SaveChangesAsync();

    return webJobStatusId;
}

I mocked dbset and dbcontext

public async void CreateWebJobStatusTest() {
    var dbOption = new DbContextOptions<TimeSeriesDbContext>();
    var mockDbContext = new Mock<TimeSeriesDbContext>(dbOption);
    var mockConfig = new Mock<IConfiguration>();
    var instance = new WebJobStatusRepository(mockConfig.Object, mockDbContext.Object);
    var mockValidWebJobId = "11111111-1111-1111-1111-111111111111";
    var webjobStatusList = new List<WebJobStatus>() {
        new WebJobStatus {
            WorkJobStatusId = Guid.Parse(mockValidWebJobId),
            GroupName = "testGroupName",
            Status = 3,
            CreatedDate = DateTimeOffset.UtcNow.AddDays(-10)
        }
    };
    var mockWebJobDbSet = UnitTestUtil.CreateDbSetMock<WebJobStatus>(webjobStatusList.AsQueryable());
    mockDbContext.Setup(x => x.WebJobStatus).Returns(mockWebJobDbSet.Object);

    mockWebJobDbSet.Setup(x => x.AddAsync(It.IsAny<WebJobStatus>(), It.IsAny<System.Threading.CancellationToken>())).Callback((WebJobStatus wj) =>{webjobstatusList.add(wj);});


    var mockuserId = Guid.Parse("22222222-1111-1111-1111-111111111111");

    var result = await instance.CreateWebJobStatus("testBlobId.tsv", mockuserId, "testEmail");
    Assert.IsType<Guid>(result);
    mockDbContext.Verify(x => x.SaveChangesAsync(It.IsAny<System.Threading.CancellationToken>()), Times.Once);
    mockWebJobDbSet.Verify(x => x.AddAsync(It.IsAny<WebJobStatus>(), It.IsAny<System.Threading.CancellationToken>()), Times.Once);
}

everything works as expect except the AddAsync, the exception is

Invalid callback. Setup on method with parameters (WebJobStatus,CancellationToken) cannot invoke callback with parameters (WebJobStatus).

Anyone has any idea?

Answer 1

You will need to return a Task to allow the async/await call

await _dbContext.WebJobStatus.AddAsync(newWebJobStatus);

to flow to completion.

So assuming that Add returns the object added

mockWebJobDbSet
    .Setup(_ => _.AddAsync(It.IsAny<WebJobStatus>(), It.IsAny<System.Threading.CancellationToken>()))
    .Callback((WebJobStatus model, CancellationToken token) => { webjobstatusList.Add(model); })
    .Returns((WebJobStatus model, CancellationToken token) => Task.FromResult((EntityEntry<WebJobStatus>)null));

Note that the method being Setup takes two arguments, so the Callback and Returns will need to expect two arguments as well if they want to use the captured arguments.