public void ContainsAllUniqueCharacters_aa_returns_false()
 {
     Assert.IsFalse(ArrayAndString.ContainsAllUniqueCharacters("aa"));
 }
 public void ContainsAllUniqueCharacters_abc_returns_true()
 {
     Assert.IsTrue(ArrayAndString.ContainsAllUniqueCharacters("abc"));
 }
 public void ContainsAllUniqueCharacters_empty_returns_true()
 {
     Assert.IsTrue(ArrayAndString.ContainsAllUniqueCharacters(string.Empty));
 }