Add EasyGo strategy

Author: geraintpalmer

axelrod/strategies/_strategies.py

@@ -29,7 +29,7 @@
     HardGoByMajority5)
 from .gradualkiller import GradualKiller
 from .grudger import (Grudger, ForgetfulGrudger, OppositeGrudger, Aggravater,
-    SoftGrudger, GrudgerAlternator)
+    SoftGrudger, GrudgerAlternator, EasyGo)
 from .grumpy import Grumpy
 from .handshake import Handshake
 from .hunter import (
@@ -97,6 +97,7 @@
     DefectorHunter,
     Desperate,
     DoubleCrosser,
+    EasyGo,
     Eatherley,
     EventualCycleHunter,
     Feld,

axelrod/strategies/grudger.py

@@ -201,3 +201,32 @@ def strategy(self, opponent):
             if self.history[-1] == Actions.C:
                 return Actions.D
         return Actions.C
+
+
+
+class EasyGo(Player):
+    """
+    A player starts by defecting however will cooperate if at any point the opponent has defected.
+
+    Names:
+
+    - Easy Go [PRISON1998]_
+    """
+
+    name = 'EasyGo'
+    classifier = {
+        'memory_depth': float('inf'),  # Long memory
+        'stochastic': False,
+        'makes_use_of': set(),
+        'long_run_time': False,
+        'inspects_source': False,
+        'manipulates_source': False,
+        'manipulates_state': False
+    }
+
+    @staticmethod
+    def strategy(opponent):
+        """Begins by playing D, then plays C for the remaining rounds if the opponent ever plays D."""
+        if opponent.defections:
+            return C
+        return D

axelrod/tests/unit/test_grudger.py

@@ -227,3 +227,33 @@ def test_starategy_random_number_rounds(self):
             my_hist = [C] * (i + 1)
             expected_response = [D if r % 2 == 0 else C for r in range(j)]
             self.responses_test(my_hist, opp_hist, expected_response)
+
+
+
+
+class TestEasyGo(TestPlayer):
+
+    name = "EasyGo"
+    player = axelrod.EasyGo
+    expected_classifier = {
+        'memory_depth': float('inf'),  # Long memory
+        'stochastic': False,
+        'makes_use_of': set(),
+        'long_run_time': False,
+        'inspects_source': False,
+        'manipulates_source': False,
+        'manipulates_state': False
+    }
+
+    def test_initial_strategy(self):
+        """
+        Starts by cooperating
+        """
+        self.first_play_test(D)
+
+    def test_strategy(self):
+        """
+        If opponent defects at any point then the player will cooperate forever
+        """
+        self.responses_test([C, D, D, D], [C, C, C, C], [D])
+        self.responses_test([C, C, D, D, D], [C, D, C, C, C], [C])