Question

I am writing some unit tests for an extension method I have written on IPrincipal. To assist, I have created a couple of helper classes (some code for not-implemented members of the interfaces has been omitted for brevity):

public class IPrincipalStub : IPrincipal
{
    private IIdentity identityStub = new IIdentityStub();

    public IIdentity Identity
    {
        get { return identityStub; }
        set { identityStub = value; }
    }
}

public class IIdentityStub : IIdentity
{
    public string Name { get; set; } // BZZZT!!!
}

However, the Name property in the IIdentity interface is read-only (the IIDentity interface specifies a getter but not a setter for the Name property).

How can I set the Name property in my stub object for testing purposes if the interface has defined it as a read-only property?

Answer 1

You’re using the auto-properties feature of C# but instead you should go the manual route and create a backing field for the property. Once you have a backing field you can set its value in the constructor (or make it a public field and set it after you have the object, but this is a little uglier).

public class IIdentityStub : IIdentity{
    private string _name;

    public IIdentityStub(string name){
        _name = name;
    }

    public string Name { get { return _name; } }
}