当我在测试中设置IMediator Mock时，它返回空

IMediator Mock returns null when I set up it in test(当我在测试中设置IMediator Mock时，它返回空)

问题描述

以下是我的代码：

public sealed class BulkAddStockConditionItemCommandHandler : IRequestHandler<BulkAddStockConditionItemCommand,
    UserStockConditionSetsEntity>
{

    private readonly IMediator _mediator;


    public BulkAddStockConditionItemCommandHandler(IMediator mediator)
    {

        _mediator = mediator;
  
    }

    public async Task<UserStockConditionSetsEntity> Handle(BulkAddStockConditionItemCommand request,
        CancellationToken cancellationToken)
    {
        var conditionalRiskAgreements = new ConditionalRiskAgreementEntity(_userService.CustomerIsin);

        var addRes = await _mediator.Send(new AcceptConditionalRiskAgreementCommand(), cancellationToken);

        if (addRes == null) throw new Exception();


        //...code removed for brevity
    }
}

我将IMediator注入到我的构造函数中，并且在我的单元测试场景中需要addRes不是NULL，因此您可以在这里看到我的测试场景：

public async void BulkAddStockConditionItemCommand_when_StockConditionSet_is_null()
{
    //arrange
    
    var condition = new ConditionalRiskAgreementEntity(RandomIsin);

    var mediator = new Mock<IMediator>();

    mediator.Setup(i => i.Send(It.IsAny<ConditionalRiskAgreementEntity>(), It.IsAny<System.Threading.CancellationToken>())).ReturnsAsync(Task.FromResult<object>(condition));

    BulkAddStockConditionItemCommand command = new BulkAddStockConditionItemCommand(data);
    BulkAddStockConditionItemCommandHandler handler = new BulkAddStockConditionItemCommandHandler(mediator.Object, userservice.Object, repoacc.Object, CacheableRepository.Object);

    //Act

    var caughtException = await Assert.ThrowsAsync<Exception>(() => handler.Handle(command, new System.Threading.CancellationToken()));

    //Assert
    Assert.IsType<Exception>(caughtException);

}

我将IMediator设置为，但是当我运行测试时，它返回null而不是condition 变量。为什么？

推荐答案

根据显示的代码，测试对象使用AcceptConditionalRiskAgreementCommand

//...

var addRes = await _mediator.Send(new AcceptConditionalRiskAgreementCommand(), cancellationToken);

//...

但在测试中，模拟调解器设置为预期ConditionalRiskAgreementEntity

//...

mediator.Setup(i => i.Send(It.IsAny<ConditionalRiskAgreementEntity>(), It.IsAny<System.Threading.CancellationToken>()))
    .ReturnsAsync(Task.FromResult<object>(condition));

//...

默认情况下，当参数匹配器在被调用的成员中不匹配时，模拟将返回NULL。

不需要在ReturnsAsync中返回Task.FromResult<object>(condition)，因为这将包装您在Task

中传递的任何内容

首先，我建议您重构测试以使用async Task而不是async void，然后更新模拟以预期测试对象中使用的实际参数类型。

public async Task BulkAddStockConditionItemCommand_when_StockConditionSet_is_null() {
    //Arrange
    var condition = new ConditionalRiskAgreementEntity(RandomIsin);

    var mediator = new Mock<IMediator>();

    mediator
        .Setup(i => i.Send(It.IsAny<AcceptConditionalRiskAgreementCommand>(), It.IsAny<System.Threading.CancellationToken>()))
        .ReturnsAsync(condition);

    BulkAddStockConditionItemCommand command = new BulkAddStockConditionItemCommand(data);
    BulkAddStockConditionItemCommandHandler handler = new BulkAddStockConditionItemCommandHandler(mediator.Object, userservice.Object, repoacc.Object, CacheableRepository.Object);

    //Act
    var caughtException = await Assert.ThrowsAsync<Exception>(() => handler.Handle(command, new System.Threading.CancellationToken()));

    //Assert
    Assert.IsType<Exception>(caughtException);
}

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