public void match_alphabetTest()
{
var dmp = new diff_match_patchTest();
// Initialise the bitmasks for Bitap.
var bitmask = new Dictionary<char, int>{{'a', 4}, {'b', 2}, {'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.");
}