Use lowercase

qgram.py

@@ -40,7 +40,7 @@ class QGramIndex:
             jaccard = count / (n_term + n_query - count)
             result.append((jaccard, term))
 
-        result.sort(key=lambda x: x[0])
+        result.sort(key=lambda x: -x[0])
 
         return result
 
@@ -55,7 +55,7 @@ class QGramIndex:
         The beginning and end of the string is denoted by a dollar sign ($).
         If the term is too short, the qgrams might be shorter than q.
         """
-        term = f"${term}$"
+        term = f"${term}$".lower()
         qgrams = []
 
         if len(term) < self.q_param:

test_qgram.py

@@ -9,6 +9,12 @@ from qgram import QGramIndex
 class QGramChunkTest(unittest.TestCase):
     """Test the  implementation"""
 
+    def test_case(self):
+        """Test the chunk converts to lower case"""
+        index = QGramIndex()
+        qgrams = index._chunk("WeaTHer")
+        self.assertEqual(qgrams, ["$we", "wea", "eat", "ath", "the", "her", "er$"])
+
     def test_long(self):
         """Test the chunk method with a long string"""
         index = QGramIndex()