Question

如何使用Moq验证方法是否只调用一次？ Verify()与Verifable()之间的关系非常混乱。

Answer 1

您可以使用Times.Once()或Times.Exactly(1)：

mockContext.Verify(x => x.SaveChanges(), Times.Once());
mockContext.Verify(x => x.SaveChanges(), Times.Exactly(1));

以下是Times类的方法：

AtLeast - 指定应该按次数调用模拟方法。
AtLeastOnce - 指定应该至少调用一次模拟方法。
AtMost - 指定应该按时间调用模拟方法作为最大值。
AtMostOnce - 指定应该最多调用一次模拟方法。
Between - 指定应在from和to之间调用模拟方法。
Exactly - 指定应该多次调用模拟方法。
Never - 指定不应调用模拟方法。
Once - 指定应该只调用一次模拟方法。

请记住，他们是方法调用;我不断被绊倒，认为他们是属性而忘记了括号。

Answer 2

想象一下，我们正在构建一个计算器，其中包含一种添加2个整数的方法。让我们进一步想象一下，当调用add方法时，它会调用print方法一次。以下是我们如何测试这个：

public interface IPrinter
{
    void Print(int answer);
}

public class ConsolePrinter : IPrinter
{
    public void Print(int answer)
    {
        Console.WriteLine("The answer is {0}.", answer);
    }
}

public class Calculator
{
    private IPrinter printer;
    public Calculator(IPrinter printer)
    {
        this.printer = printer;
    }

    public void Add(int num1, int num2)
    {
        printer.Print(num1 + num2);
    }
}

以下是代码中包含注释的实际测试，以便进一步说明：

[TestClass]
public class CalculatorTests
{
    [TestMethod]
    public void WhenAddIsCalled__ItShouldCallPrint()
    {
        /* Arrange */
        var iPrinterMock = new Mock<IPrinter>();

        // Let's mock the method so when it is called, we handle it
        iPrinterMock.Setup(x => x.Print(It.IsAny<int>()));

        // Create the calculator and pass the mocked printer to it
        var calculator = new Calculator(iPrinterMock.Object);

        /* Act */
        calculator.Add(1, 1);

        /* Assert */
        // Let's make sure that the calculator's Add method called printer.Print. Here we are making sure it is called once but this is optional
        iPrinterMock.Verify(x => x.Print(It.IsAny<int>()), Times.Once);

        // Or we can be more specific and ensure that Print was called with the correct parameter.
        iPrinterMock.Verify(x => x.Print(3), Times.Once);
    }
}

Answer 3

测试控制器可能是：

  public HttpResponseMessage DeleteCars(HttpRequestMessage request, int id)
    {
        Car item = _service.Get(id);
        if (item == null)
        {
            return request.CreateResponse(HttpStatusCode.NotFound);
        }

        _service.Remove(id);
        return request.CreateResponse(HttpStatusCode.OK);
    }

当使用有效id调用DeleteCars方法时，我们可以通过此测试验证，Service remove方法只调用一次：

 [TestMethod]
    public void Delete_WhenInvokedWithValidId_ShouldBeCalledRevomeOnce()
    {
        //arange
        const int carid = 10;
        var car = new Car() { Id = carid, Year = 2001, Model = "TTT", Make = "CAR 1", Price=2000 };
        mockCarService.Setup(x => x.Get(It.IsAny<int>())).Returns(car);

        var httpRequestMessage = new HttpRequestMessage();
        httpRequestMessage.Properties[HttpPropertyKeys.HttpConfigurationKey] = new HttpConfiguration();

        //act
        var result = carController.DeleteCar(httpRequestMessage, vechileId);

        //assert
        mockCarService.Verify(x => x.Remove(carid), Times.Exactly(1));
    }

如何使用Moq验证方法是否只调用一次？

3 个答案: