How to MOQ an Indexed property

object result = myDictionaryCollection["SomeKeyValue"];

myDictionaryCollection["SomeKeyValue"] = myNewValue;

Dictionary<string, object> MyContainer = new Dictionary<string, object>();
mock.ExpectGet<object>( p => p[It.IsAny<string>()]).Returns(MyContainer[(string s)]);

/// <summary>
/// HTTP session mockup.
/// </summary>
internal sealed class HttpSessionMock : HttpSessionStateBase
{
    private readonly Dictionary<string, object> objects = new Dictionary<string, object>();

    public override object this[string name]
    {
        get { return (objects.ContainsKey(name)) ? objects[name] : null; }
        set { objects[name] = value; }
    }
}

/// <summary>
/// Base class for all controller tests.
/// </summary>
public class ControllerTestSuiteBase : TestSuiteBase
{
    private readonly HttpSessionMock sessionMock = new HttpSessionMock();

    protected readonly Mock<HttpContextBase> Context = new Mock<HttpContextBase>();
    protected readonly Mock<HttpSessionStateBase> Session = new Mock<HttpSessionStateBase>();

    public ControllerTestSuiteBase()
        : base()
    {
        Context.Expect(ctx => ctx.Session).Returns(sessionMock);
    }
}

var mock = new Mock<IDictionary>();
        mock.SetupGet( p => p[It.IsAny<string>()]).Returns("foo");