public void GetPermutationsReturnsCorrectListOfPermutations()
{
var actualPermutations = stringProblems.GetPermutations("aab");
Assert.AreEqual(3, actualPermutations.Count());
Assert.IsTrue(actualPermutations.Contains("aab"));
Assert.IsTrue(actualPermutations.Contains("aba"));
Assert.IsTrue(actualPermutations.Contains("baa"));
}