模拟虚拟方法，而不是使用 Moq 模拟重写该方法

Question

在下面的代码中，我想模拟类GetTitle(int id)中的数据库操作FooBase。但我想测试 overrided 中的验证部分GetTitle(int id)。

我想测试重写的方法但模拟基本方法

我如何模拟虚拟方法并测试它的重写？

public abstract class FooBase
{
    public virtual string GetTitle(int id) { return "Title From DB" /*Select From DB*/; }
}

public class Foo : FooBase
{
    public override string GetTitle(int id)
    {
        if (id < 0)
            return "Invalid id";

        /*Doing somethings like other validations and etc*/

        return $"Valid ID ({base.GetTitle(id)})";
    }
}

public class FooTests
{
    [Fact]
    public void GetTitle() // Fails
    {
        // Arrange
        var expectedID = 1;
        var expectedResult = "Test";
        var fooMock = new Mock<Foo>();
        fooMock.Setup(x => x.GetTitle(It.IsAny<int>())).Returns(expectedResult);
        var foo = fooMock.Object;

        // Act
        var title = foo.GetTitle(expectedID);

        // Assert
        fooMock.Verify(x => x.GetTitle(It.Is<int>(c => expectedID == c)), Times.Once);
        Assert.Equal($"Valid ID ({expectedResult})", title);
    }
}

Answer 1

如果您可以将逻辑分离到不同的方法中（这也可能是更好的设计），那么您可以使用 Moq 的CallBase属性来使测试调用模拟方法。

public abstract class FooBase
{
   public virtual string GetTitle(int id) { return "Title From DB" /*Select From DB*/; }
}

public class Foo : FooBase
{
  public virtual string GetValidatedTitle(int id)
  {
    if (id < 0)
    return "Invalid id";

    /*Doing somethings like other validations and etc*/

    return $"Valid ID ({GetTitle(id)})";
  }
}

public class FooTests
{
  [Fact]
  public void GetTitle() // Now Passes
  {
    // Arrange
    var expectedID = 1;
    var expectedResult = "Test";
    var fooMock = new Mock<Foo>() { CallBase = true };
    fooMock.Setup(x => x.GetTitle(It.IsAny<int>())).Returns(expectedResult);
    var foo = fooMock.Object;

    // Act
    var title = foo.GetValidatedTitle(expectedID);

    // Assert
    fooMock.Verify(x => x.GetTitle(It.Is<int>(c => expectedID == c)), Times.Once);
    Assert.Equal($"Valid ID ({expectedResult})", title);
  }
}