public void IndexOfItems()
{
var list = new ListHistory <string>
{
"a",
"b",
"c",
"d",
"e",
"f",
};
Assert.AreEqual(0, list.IndexOf("a"));
Assert.AreEqual(1, list.IndexOf("b"));
Assert.AreEqual(2, list.IndexOf("c"));
Assert.AreEqual(3, list.IndexOf("d"));
Assert.AreEqual(4, list.IndexOf("e"));
Assert.AreEqual(5, list.IndexOf("f"));
}