原文： https://riptutorial.com/moq/example/27613/mocking-protected-members

To mock a protected member you must first include the following at the top of your test fixture:

using Moq.Protected;

You then call Protected() on your mock, after which you can use the generic Setup<> with the return type of your method.

var mock = new Mock<MyClass>();
mock.Protected()
     .Setup<int>("MyProtectedGetIntMethod")
     .Returns(1);

If the method returns void then use the non-generic Setup().