I have a mocked the GetByEmail method to return a mocked IMember. The returned IMember is the basic IMember with no extended properties.

To progress thought the test I have to be able to call SetValue on the IMember, as this happens in the code I am testing.

So in the code I am testing I have

var customMember = _memberService.GetByEmail(member.Email);

And in the test I have

_mockMemberService.Setup(x => x.GetByEmail(It.IsAny<string>())).Returns(new Member("test name", new MemberType(12)));

Then in the code I set a value:

customMember.SetValue("firstName", member.FirstName);

But this crashes the test as there is no firstName property on IMember, although there is in the back office.

How can I mock adding or setting these extended properties?

Thanks