static void Main()
    {
        Console.WriteLine("Enter a sentence:");
        string sentence = Console.ReadLine();

        Console.WriteLine("Enter the word you'd like to count:");
        string        word          = Console.ReadLine();
        RepeatCounter counter       = new RepeatCounter();
        string        checkValidity = counter.CheckValidity(sentence, word);

        if (checkValidity == "valid")
        {
            int repeats = counter.CountRepeats(sentence, word);
            Console.WriteLine("Number of times \"" + word + "\" was found: " + repeats);
        }
        else
        {
            Console.WriteLine(checkValidity);
            Main();
        }
    }
 public void CountRepeats_SingleWordSearch_TryAgain()
 {
     Assert.AreEqual("Can only search for a single word. Please try again.", testCounter.CheckValidity("I own a Cat.", "cat dog"));
 }