Case 2: If null, return an empty String

    public void testIfNullReturnEmpty() {

        assertEquals("If Null", "" , FormatDate.formatDate(null));

    }

Case 3: If single M, append '0' and return in format MM-DD-YYYY

    public void testSingleM() {

        assertEquals("Single M", "01-11-2003", FormatDate.formatDate("1-11-2003"));

    }

Case 4: If single D, append '0' and return in format MM-DD-YYYY

    public void testSingleD() {

        assertEquals("Single D","11-01-2003", FormatDate.formatDate("11-01-2003"));

    }

Case 5: If two Ys instead of four, append '20' and return in format MM-DD-YYYY

    public void testDoubleY() {

        assertEquals("11-11-2003", FormatDate.formatDate("11-11-03"));

    }

Case 6: If valid input in format MM-DD-YYYY, return as MM-DD-YYYY

    public void testValid() {

        assertEquals("Valid Case","11-11-2003", FormatDate.formatDate("11-11-2003"));

    }