Fix coverage of meta.py

axelrod/strategies/hunter.py

@@ -49,7 +49,7 @@ def strategy(self, opponent: Player) -> Action:
 
 def is_alternator(history: List[Action]) -> bool:
     for i in range(len(history) - 1):
-        if history[i] == history[i + 1]:
+        if history[i] == history[i + 1] or history[i] not in (C, D):
             return False
     return True
 

axelrod/tests/strategies/test_meta.py

@@ -248,7 +248,15 @@ def test_strategy(self):
         self.responses_test([D], [C, C, C, C], [C, C, C, C])
 
         # After long histories tit-for-tat should come into play.
-        self.responses_test([D], [C] * 101, [C] * 100 + [D])
+        # We generate a 'junk' history of length 101 in order to avoid the
+        # hunters triggering a defection as that overrides the tit-for-tat
+        # action.
+        # A genuine history (based on C or D only) which does not trigger any
+        # of the hunters is extremely difficult to identify. None of the
+        # strategies as at 14-Mar-2017 avoids doing so.
+        letters = 'ABEFGHIJKLMNOPQRSTUVWXYZ'
+        junk_history = [random.choice(letters) for _ in range(101)]
+        self.responses_test([D], junk_history, junk_history[:100] + [D])
 
         # All these others, however, should trigger a defection for the hunter.
         self.responses_test([D], [C] * 4, [D] * 4)