LinqSamenessTest.cs

public class Quote
{
    public string Word { get; set; }
}

[Fact]
void LinqSingleMethod_WhenLazilyEvaluated_ReturnsDifferentInstance()
{
    var quoteWords = new[]
        {
            new  {Word = "Never"},
            new  {Word = "Attribute"},
            new  {Word = "To"},
            new  {Word = "Malice"},
            new  {Word = "That"},
            new  {Word = "Which"},
            new  {Word = "Is"},
            new  {Word = "Adequately"},
            new  {Word = "Explained"},
            new  {Word = "By"},
            new  {Word = "Stupidity"}
        };

    var transformedWithSelect = quoteWords.Select(c => new Quote { Word = c.Word });

    var firstSingle = transformedWithSelect.Single(c => c.Word == "Adequately");
    var secondSingle = transformedWithSelect.Single(c => c.Word == "Adequately");

    Assert.NotSame(firstSingle, secondSingle);
}

[Fact]
void LinqSingleMethod_WhenNotLazilyEvaluated_ReturnsSameInstance()
{
    var quoteWords = new[]
    {
        new  {Word = "Never"},
        new  {Word = "Attribute"},
        new  {Word = "To"},
        new  {Word = "Malice"},
        new  {Word = "That"},
        new  {Word = "Which"},
        new  {Word = "Is"},
        new  {Word = "Adequately"},
        new  {Word = "Explained"},
        new  {Word = "By"},
        new  {Word = "Stupidity"}
    };

    var transformedWithSelect = quoteWords.Select(c => new Quote { Word = c.Word }).ToList();

    var firstSingle = transformedWithSelect.Single(c => c.Word == "Adequately");
    var secondSingle = transformedWithSelect.Single(c => c.Word == "Adequately");

    Assert.Same(firstSingle, secondSingle);
}