Make utility function return a boolean.

Author: drvinceknight

axelrod/match_generator.py

@@ -169,18 +169,20 @@ def estimated_size(self):
         return size
 
 
-def test_graph_is_connected(edges, players):
+def graph_is_connected(edges, players):
     """
     Test if a set of edges defines a complete graph on a set of players.
 
-    This is used by the spatial tournaments and will raise a ValueError if the
-    graph would have some players not playing anyone.
+    This is used by the spatial tournaments.
 
     Parameters:
     -----------
+    edges : a list of 2 tuples
+    players : a list of player names
 
-        edges : a list of 2 tuples
-        players : a list of player names
+    Returns:
+    --------
+    boolean : True if the graph is connected
     """
     # Check if all players are connected.
     player_indices = set(range(len(players)))
@@ -189,8 +191,7 @@ def test_graph_is_connected(edges, players):
         for node in edge:
             node_indices.add(node)
 
-    if player_indices != node_indices:
-        raise ValueError("The graph edges do not include all players.")
+    return player_indices == node_indices
 
 
 
@@ -217,7 +218,8 @@ class SpatialMatches(RoundRobinMatches):
 
     def __init__(self, players, turns, game, repetitions, edges):
 
-        test_graph_is_connected(edges, players)
+        if not graph_is_connected(edges, players):
+            raise ValueError("The graph edges do not include all players.")
         self.edges = edges
         super(SpatialMatches, self).__init__(players, turns, game, repetitions)
 
@@ -254,7 +256,8 @@ class ProbEndSpatialMatches(SpatialMatches, ProbEndRoundRobinMatches):
 
     def __init__(self, players, prob_end, game, repetitions, noise, edges):
 
-        test_graph_is_connected(edges, players)
+        if not graph_is_connected(edges, players):
+            raise ValueError("The graph edges do not include all players.")
         self.edges = edges
         ProbEndRoundRobinMatches.__init__(self, players, prob_end,
                                           game, repetitions, noise)

axelrod/tests/unit/test_match_generator.py

@@ -5,7 +5,7 @@
 from hypothesis.strategies import floats, integers
 
 import axelrod
-from axelrod.match_generator import test_graph_is_connected
+from axelrod.match_generator import graph_is_connected
 
 
 test_strategies = [
@@ -270,6 +270,14 @@ def test_build_match_chunks(self, repetitions, prob_end, noise):
 
         self.assertEqual(match_definitions, expected_match_definitions)
 
+    def test_raise_error_if_not_connected(self):
+        edges = [(0, 0), (0, 1), (1, 1)]
+        players = ["Cooperator", "Defector", "Alternator"]
+        noise = 0
+        self.assertRaises(ValueError, axelrod.ProbEndSpatialMatches,
+                          players, test_turns, test_game, test_repetitions,
+                          noise, edges)
+
     def test_len(self):
         edges = [(0, 1), (1, 2), (3, 4)]
         noise = 0
@@ -326,9 +334,9 @@ class TestUtilityFunctions(unittest.TestCase):
     def test_connected_graph(self):
         edges = [(0, 0), (0, 1), (1, 1)]
         players = ["Cooperator", "Defector"]
-        self.assertEqual(test_graph_is_connected(edges, players), None)
+        self.assertTrue(graph_is_connected(edges, players))
 
     def test_unconnected_graph(self):
         edges = [(0, 0), (0, 1), (1, 1)]
         players = ["Cooperator", "Defector", "Alternator"]
-        self.assertRaises(ValueError, test_graph_is_connected, edges, players)
+        self.assertFalse(graph_is_connected(edges, players))