Merge pull request #761 from drvinceknight/760

Stop random_choice sampling when used with 0 or 1

Author: meatballs

axelrod/random_.py

@@ -8,7 +8,23 @@ def random_choice(p=0.5):
     Return 'C' with probability `p`, else return 'D'
 
     Emulates Python's random.choice(['C', 'D']) since it is not consistent
-    across Python 2.7 to Python 3.4"""
+    across Python 2.7 to Python 3.4
+
+    Parameters
+    ----------
+
+    p : float
+        The probability of picking 'C'
+
+    Returns
+    -------
+    axelrod.Actions.C or axelrod.Actions.D
+    """
+    if p == 0:
+        return Actions.D
+
+    if p == 1:
+        return Actions.C
 
     r = random.random()
     if r < p:

axelrod/tests/unit/test_axelrod_second.py

@@ -80,7 +80,7 @@ def test_strategy(self):
         # Test defection after opponent defection
         self.responses_test([D], [D], [D])
         self.responses_test([D, D], [D, D], [D])
-        self.responses_test([D, C, C, D], [D, C, C, D], [D, C], random_seed=8)
+        self.responses_test([D, C, C, D], [D, C, C, D], [C, C], random_seed=8)
 
 
 class TestTester(TestPlayer):

axelrod/tests/unit/test_headsup.py

@@ -38,7 +38,7 @@ def test_rounds(self):
 class TestZDGTFT2vsBully(TestHeadsUp):
     """Test ZDGTFT2 vs Bully"""
     def test_rounds(self):
-        self.versus_test(axelrod.ZDGTFT2(), axelrod.Bully(), [C, D, D, C, C, D],
+        self.versus_test(axelrod.ZDGTFT2(), axelrod.Bully(), [C, D, D, C, C, C],
             [D, D, C, C, D, D], random_seed=2)
 
 

axelrod/tests/unit/test_memoryone.py

@@ -229,7 +229,7 @@ def test_effect_of_strategy(self):
         self.responses_test([C], [C], [D, D, C, C], random_seed=2)
         self.responses_test([C], [D], [D, D, C, C], random_seed=2)
         self.responses_test([D], [C], [D, D, C, C], random_seed=2)
-        self.responses_test([D], [D], [D, D, C, C], random_seed=2)
+        self.responses_test([C], [D], [D, D, C, C], random_seed=2)
 
 
 class TestZDExtort2v2(TestPlayer):

axelrod/tests/unit/test_random_.py

@@ -8,14 +8,15 @@
 
 C, D = Actions.C, Actions.D
 
+
 class TestRandom_(unittest.TestCase):
 
     def test_return_values(self):
         self.assertEqual(random_choice(1), C)
         self.assertEqual(random_choice(0), D)
-        random.seed(1)
+        seed(1)
         self.assertEqual(random_choice(), C)
-        random.seed(2)
+        seed(2)
         self.assertEqual(random_choice(), D)
 
     def test_set_seed(self):
@@ -30,3 +31,14 @@ def test_set_seed(self):
 
         self.assertEqual(numpy_random_numbers[0], numpy_random_numbers[1])
         self.assertEqual(stdlib_random_numbers[0], stdlib_random_numbers[1])
+
+    def test_seed_not_offset_by_deterministic_call(self):
+        """Test that when called with p = 0 or 1, the random seed is not
+        affected"""
+        for p in [0, 1]:
+            seed(0)
+            r = random.random()
+
+            random.seed(0)
+            random_choice(p)
+            self.assertEqual(r, random.random())