Added party XP thresholds to GM sheets.

tests/test_encounter.py

@@ -0,0 +1,17 @@
+from unittest import TestCase
+
+from dungeonsheets import stats, character, encounter
+
+
+class TestStats(TestCase):
+    def new_character(self, level=1):
+        return character.Character(classes=['cleric'], levels=[level])
+    
+    def test_xp_thresholds(self):
+        # One level 1 character
+        xp_th = encounter.xp_thresholds([self.new_character(1)])
+        self.assertEqual(xp_th, (25, 50, 75, 100))
+        # Three mixed-level characters
+        party = [self.new_character(9), self.new_character(8), self.new_character(6)]
+        xp_th = encounter.xp_thresholds(party)
+        self.assertEqual(xp_th, (1300, 2600, 3900, 5900))