have c# random tests been sabotaged?

Assert.That(Kata.MakesTheSentence(new List { 'j', 'm', 'j', 'f', 'd', 'c', 'n', '!', 't', 'I', 'u', 'b', 'k', 'y', 'n', 'e', 'm', 'l', 'k', 'e', 'x', 'j', 'p', 't', 'b', 'q', 'z', 't', 'd', 't', 'q', 'y', 'g', 'u', 'f', 'p', 'e', 'y', 'l', 'x', 'p', 'h', 'v', 'v', 'k', 'z', 'f', 'x' }, "Iftpyucn mpvxf ebfhdnj mgujqlkz eydtxez qpbkyv jttxlk!"), Is.EqualTo(false));

False? really? How is that?

wth is [i..] ? ;-)

Nothing wrong withe a Kata. Your code is just wrong. Return the right value for v and s prop.