public void ConvertTest()
 {
     var l = SystemEnumerable.Convert(list, x => x.ToString()).ToList();
     Assert.AreEqual(6, list.Count);
     Assert.AreEqual("1", l[0]);
     Assert.AreEqual("3", l[1]);
     Assert.AreEqual("2", l[2]);
     Assert.AreEqual("4", l[3]);
     Assert.AreEqual("1", l[4]);
     Assert.AreEqual("6", l[5]);
 }
 [TestMethod] public void ConvertWithNullArgumentsTest()
 {
     Assert.AreEqual(0, SystemEnumerable.Convert <int, string>(list, null).Count());
     Assert.AreEqual(0, SystemEnumerable.Convert <int, string>(null, x => x.ToString()).Count());
     Assert.AreEqual(0, SystemEnumerable.Convert <int, string>(null, null).Count());
 }