使用 NUnit 和 Moq 进行测试时意外的空引用

Question

我在运行进行测试时遇到空引用错误，但无法弄清楚。下面是我的测试

[Test]
[TestCase(...)]
public void Get_ShouldReturnTradesMock(string field, Operator op, int dayManip, SortDirection sortDir, string filterTerm, int pageIndex, int pageSize, int expectedRecordMinSize)
{
    using (var _imprintDbContext = new ImprintDbContext(_dbContextOptions))
    {
        var mockExecRepo = new Mock<IExecutionReportRepository>();
        mockExecRepo.Setup(mock => mock.GetFilteredTrades(It.IsAny<IEnumerable<Query>>(), It.IsAny<int>(), It.IsAny<int>(), It.IsAny<string>())).Verifiable();//.Returns<Task<PagedResult<ExecutionReport>>>(x => null);

        var uow = new Mock<IUnitOfWork>();
        uow.SetupGet(x => x.ExecutionReports).Returns(mockExecRepo.Object);

        var controller = new TradesController(uow.Object);

        var query = new Query()
        {
            Field = field,
            Operator = op,
            Search = DateTime.Now.Add(TimeSpan.FromDays(dayManip)).Date.ToString("yyyy-MM-dd"),
            SortDirection = sortDir
        };

        TradesController.TradesBody tb = new TradesController.TradesBody()
        {
            queries = new[] { query },
            filterTerm = filterTerm
        };

        var results = controller.Get(tb, pageIndex, pageSize);

        uow.Verify(mock => mock.ExecutionReports.GetFilteredTrades(new[] { query }, pageIndex, pageSize, filterTerm), Times.Once());
    }
}

以及我正在模拟的一些对象的定义：

public interface IExecutionReportRepository : IRepository<ExecutionReport>
{
    ...
    Task<IPagedResult<ExecutionReport>> GetFilteredTrades(IEnumerable<Query> queries, int pageIndex, int pageSize, string filterTerm);

}

工作单位：

public class UnitOfWork : IUnitOfWork
{
    private readonly DbContext _context;

    public UnitOfWork(DbContext context, IExecutionReportRepository executionReportRepository)
    {
        _context = context;
        ExecutionReports = executionReportRepository;
    }

    public IExecutionReportRepository ExecutionReports { get; }
}

交易控制器：

public class TradesController : Controller
{
    public class TradesBody
    {
        public IEnumerable<Query> queries;
        public string filterTerm;
    }

    private readonly IUnitOfWork unitOfWork;

    public TradesController(IUnitOfWork unitOfWork)
    {
        this.unitOfWork = unitOfWork;
    }

    /// <summary>
    /// Gets a list of trades for the current date
    /// </summary>
    [HttpPost]
    public async Task<IActionResult> Get([FromBody] TradesBody postBody, int pageIndex = 0, int pageSize = 100)
    {
            string filterTerm = postBody.filterTerm ?? "";
            IEnumerable<Query> queries = postBody.queries;
            IPagedResult<Domain.Entities.Core.ExecutionReport> queryResult;
            queryResult = await unitOfWork.ExecutionReports.GetFilteredTrades(queries, pageIndex, pageSize, filterTerm); //Null reference error here
            return Ok(queryResult);
    }
}

单步执行代码时，我没有看到任何空对象，因此实际上无法 see/understand 在实际找到空引用的地方，但是我注意到在调试期间我看不到方法定义对于'GetFilteredTrades。根据 this 判断，我的模拟方法没有连接到正在执行的方法，但是我只有一个 GetFilteredTrades。

如何解决 TradesController 中抛出的空引用错误并成功运行我的测试？

Answer 1

您没有设置 GetFilteredTrades 到 return 任何东西，所以当您尝试等待它时它失败了。

mockExecRepo
    .Setup(mock => mock.GetFilteredTrades(It.IsAny<IEnumerable<Query>>(), It.IsAny<int>(), It.IsAny<int>(), It.IsAny<string>()))
    .ReturnAsync(Mock.Of<IPagedResult<ExecutionReport>>()) //<--THIS
    .Verifiable();

而且被测方法是异步的，所以测试也应该是异步的。

[Test]
[TestCase(...)]
public async Task Get_ShouldReturnTradesMock(string field, Operator op, int dayManip, SortDirection sortDir, string filterTerm, int pageIndex, int pageSize, int expectedRecordMinSize)
{

等待测试调用的方法

var results = await controller.Get(tb, pageIndex, pageSize);

最后，您正在根据设置验证错误的模拟。由于 mockExecRepo 设置有 Verifiable() 那么你可以简单地在 mock 上调用 Verify()。

//...

//Act
var results = await controller.Get(tb, pageIndex, pageSize);

//Assert
mockExecRepo.Verify();

验证它是否按预期调用。

使用 NUnit 和 Moq 进行测试时意外的空引用

Unexpected null reference when testing with NUnit and Moq

c#

nunit

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