为什么Moq不运行重写的ToString方法？

Question

在下面的代码中为什么mockTest.ToString()返回Null？

编辑:在示例代码中添加注释以显示如何解决问题.

Public Sub Main()

    Try

        Dim test = New TestClass

        If test.ToString <> "stackoverflow rules" Then
            Throw New Exception("Real Failed: Actual value: <" + test.ToString + ">")
        End If

        Dim mock = New Moq.Mock(Of TestClass)()
        mock.SetupGet(Function(m As TestClass) m.Name).Returns("mock value")

        ' As per Mark's accepted answer this is the missing line of 
        ' of code to make the code work.
        ' mock.CallBase = True

        Dim mockTest = DirectCast(mock.Object, TestClass)

        If mockTest.ToString() <> "mock value" Then
            Throw New Exception("Mock Failed: Actual value: <" + mockTest.ToString + ">")
        End If

        Console.WriteLine("All tests passed.")

    Catch ex As Exception

        Console.ForegroundColor = ConsoleColor.Red
        Console.WriteLine(ex.ToString)
        Console.ForegroundColor = ConsoleColor.White

    End Try

    Console.WriteLine()
    Console.WriteLine("Finished!")
    Console.ReadKey()

End Sub

Public Class TestClass

    Public Sub New()
    End Sub

    Public Overridable ReadOnly Property Name() As String
        Get
            Return "stackoverflow rules"
        End Get
    End Property

    Public Overrides Function ToString() As String
        Return Me.Name
    End Function

End Class

Answer 1

TestClass上的Name属性和ToString方法都是虚拟/可覆盖的,这意味着Moq将模拟它们.

默认情况下,Moq为具有引用类型返回类型的成员返回null,除非您明确告诉它返回其他内容.由于字符串是引用类型,因此返回null.

您可以通过将CallBase设置为true来修复它.

如果您没有明确定义覆盖,则将CallBase设置为true将导致Moq调用基本实现:

mock.CallBase = True

在这种情况下,这将指示,因为没有eplicit设置存在使用的ToString基实现(因此调用名称属性,它模拟确实有设置).