Remove offset from test messageset sequence mapping

mapper/sequence_mapper.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
-from math import ceil
+from math import floor
 
 
 class NoMappingFound(Exception):
@@ -19,13 +19,13 @@ def map_test_messageset_1(self, sequence):
         Maps from the first testing messageset to the second testing
         messageset.
         """
-        return 'test.messageset.2', 9 + 2 * sequence
+        return 'test.messageset.2', max(0, 2 * sequence - 1)
 
     def map_test_messageset_2(self, sequence):
         """
         Maps from the second testing messageset back to the first.
         """
-        return 'test.messageset.1', max(0, int(ceil((sequence - 9) / 2.0)))
+        return 'test.messageset.1', int(floor(sequence / 2.0) + 1)
 
     def map_forward(self, messageset, sequence):
         """

mapper/tests/test_sequence_mapper.py

@@ -16,11 +16,10 @@ def test_default_mapping(self):
 
     def test_map_test_messageset_1(self):
         """
-        test.messageset.1 should map forward to test.messageset.2 with an
-        offset and scale.
+        test.messageset.1 should map forward to test.messageset.2 with a scale.
         """
-        sequence_from = [1, 2, 3]
-        sequence_to = [11, 13, 15]
+        sequence_from = [0, 1, 2, 3]
+        sequence_to = [0, 1, 3, 5]
         for seq_from, seq_to in zip(sequence_from, sequence_to):
             ms, seq = map_forward('test.messageset.1', seq_from)
             self.assertEqual(ms, 'test.messageset.2')
@@ -29,10 +28,10 @@ def test_map_test_messageset_1(self):
     def test_map_test_messageset_2(self):
         """
         test.messageset.2 should map backwards to test_messageset.1 with a
-        scale and offset.
+        scale.
         """
-        sequence_from = [0, 11, 12, 13, 14]
-        sequence_to = [0, 1, 2, 2, 3]
+        sequence_from = [1, 2, 3, 4, 5]
+        sequence_to = [1, 2, 2, 3, 3]
         for seq_from, seq_to in zip(sequence_from, sequence_to):
             ms, seq = map_backward('test.messageset.2', seq_from)
             self.assertEqual(ms, 'test.messageset.1')