为什么我的 xunit 测试结果中会出现 System.ArgumentException？

Question

Here is the method I want to write test for:

public class JobStore : IJobStore
{
    private readonly IMongoDbContext _context;

    public JobStore(IMongoDbContext context)
    {
        _context = context;
    }



    public async Task<IJob> CreateAsync(IJob job)
    {
        await _context.Jobs.InsertOneAsync(job as Job);
        return job;
    }

}

Here is my test:

public class JobStoreTest
{
    

    private readonly Mock<IMongoDbContext> _moqIMongoDbContext;
    private readonly JobStore _jobStore;

    public JobStoreTest()
    {
        _moqIMongoDbContext = new Mock<IMongoDbContext>();
        _jobStore = new JobStore(_moqIMongoDbContext.Object);


        _moqIMongoDbContext
            .Setup(_ => _.Jobs.InsertOneAsync(It.IsAny<Job>(), It.IsAny<CancellationToken>()))
            .Returns((IJob x) => Task.FromResult(x));
    }

    

    
    [Theory]
    [ClassData(typeof(JobClassesForTesting))]
    public async Task CreateAsync(IJob job)
    {
        var result = await _jobStore.CreateAsync(job);

        Assert.Equal(job,result as Job);
    }
}

Here is the result of test:

System.ArgumentException Invalid callback. Setup on method with 2 parameter(s) cannot invoke callback with different number of parameters (1).

Here is the JobClassesForTestingClass which is my scenario for testing:

public class JobClassesForTesting : IEnumerable<object[]>
{
    public IEnumerator<object[]> GetEnumerator()
    {
        yield return new object[]
        {
                new Job()
                {
                    Payload = null,
                    EntityName = "EntityNameTest1",
                    Module = "ModuleTest1",
                    MetaData = new Dictionary<string, string>(),
                    Categories = new List<JobCategory>{new JobCategory {Name = "CategoryTest1"} },
                    PublishedDate = DateTime.Now
                }
        };

        yield return new object[]
        {
                new Job()
                {
                    Payload = "PayloadTest2",
                    EntityName = "EntityNameTest2",
                    Module = "ModuleTest2",
                    MetaData = new Dictionary<string, string>(),
                    Categories = new List<JobCategory>{new JobCategory {Name = "CategoryTest2"} },
                    PublishedDate = DateTime.Now
                }
        };

        yield return new object[]
        {
                new Job()
                {
                    Payload = "PayloadTest3",
                    EntityName = "EntityNameTest3",
                    Module = "ModuleTest3",
                    MetaData = new Dictionary<string, string>(),
                    Categories = new List<JobCategory>{new JobCategory {Name = "CategoryTest3"} },
                    PublishedDate = DateTime.Now
                }
        };
    }

    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}

I want the result of the test would be as same as each of my Job objects but the result of the test is System.ArgumentException

Answer 1

The exception clearly states the problem about the arguments count mismatch.

Refactor the mock setup

  _moqIMongoDbContext
        .Setup(_ => _.Jobs.InsertOneAsync(
            It.IsAny<Job>(), 
            It.IsAny<InsertOneOptions>(),
            It.IsAny<CancellationToken>())
        )
        .Returns((Job document, InsertOneOptions options, CancellationToken token) 
            => Task.FromResult(document));

Note how the parameters in the Returns delegate/callback now matches the number and types of argument matchers used by the member that was setup.

IMongoCollection.InsertOneAsync Method (TDocument, InsertOneOptions, CancellationToken)

Task InsertOneAsync(
    TDocument document,
    InsertOneOptions options = null,
    CancellationToken cancellationToken = null
)

Reference Moq Quickstart to get a better understanding of how to use that mocking library