public void ConcatTest5()
 {
     Assert.Throws(typeof(FormatException), () => ConcatStringAlphabet.Longest("тмлуамутмут", "abcdefghijklmnopqrstvwxyz"));
 }
 public void ConcatTest4()
 {
     Assert.Throws(typeof(ArgumentNullException), () => ConcatStringAlphabet.Longest(null, "vgkkcyfggkg"));
 }
 public void ConcatTest2()
 {
     Assert.AreEqual(ConcatStringAlphabet.Longest("abcdefghijkl", "mnopqrstuvwxyz"), "abcdefghijklmnopqrstuvwxyz");
 }
 public void ConcatTest3()
 {
     Assert.Throws(typeof(FormatException), () => ConcatStringAlphabet.Longest("", ""), "");
 }
 public void ConcatTest1()
 {
     Assert.AreEqual(ConcatStringAlphabet.Longest("abcdefghijklmnopqrstuvwxyz", "vgkkcyfggkg"), "abcdefghijklmnopqrstuvwxyz");
 }