我如何验证一个方法被moq调用了一次?

你可以使用 Times.Once() 或 Times.Exactly(1) :

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

以下是关于 Times 班级:

• AtLeast -指定模拟方法的调用次数应至少为次。
• AtLeastOnce -指定至少应调用一次模拟方法。
• AtMost -指定模拟方法的调用次数应为最大时间。
• AtMostOnce -指定模拟方法最多应调用一次。
• Between -指定应在从到时间之间调用模拟方法。
• Exactly -指定模拟方法应精确调用次。
• Never -指定不应调用模拟方法。
• Once -指定模拟方法应仅调用一次。

请记住,它们是方法调用;我总是被绊倒,以为它们是属性,忘记了括号。

假设我们正在用一种方法构建一个计算器来添加2个整数。让我们进一步设想一下,要求是当调用add方法时,它调用一次print方法。下面是我们将如何测试这一点:

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);
    }
}

下面是实际的测试,在代码中添加注释,以便进一步澄清:

[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);
    }
}

测试控制器可以是:

  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);
    }

当使用有效的ID调用DeleteCars方法时,我们可以验证服务移除方法是否通过此测试准确调用了一次:

 [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));
    }