Code Example: Implementation of a factory method for unit tests, used in http://blog.zuehlke.com/?p=1421

TestSubjectFactoryMethod.cs

private Controller CreateSubject(
            string[] names = null,
            IDataSource dataSource = null)
{
    names = names ?? new[] { "Alice", "Bob", "Alfred" };
    if (dataSource == null)
    {
        var mock = new Mock<IDataSource>();
        mock.Setup(x => x.GetNames()).Returns(names);
        dataSource = mock.Object;
    }
    return new Controller(dataSource);
}