public void match_alphabetTest() {
diff_match_patchTest dmp = new diff_match_patchTest();
// Initialise the bitmasks for Bitap.
Dictionary<char, int> bitmask = new Dictionary<char, int>();
bitmask.Add('a', 4); bitmask.Add('b', 2); bitmask.Add('c', 1);
CollectionAssert.AreEqual(bitmask, dmp.match_alphabet("abc"), "match_alphabet: Unique.");
bitmask.Clear();
bitmask.Add('a', 37); bitmask.Add('b', 18); bitmask.Add('c', 8);
CollectionAssert.AreEqual(bitmask, dmp.match_alphabet("abcaba"), "match_alphabet: Duplicates.");
}