Handle case where strategy does not exist in retrieve

If the retrieve method is called with a pk that does not exist it will
throw a KeyError + Http 500. Handle this case and return a Http 404
instead.

Author: erik-sn

api/core/tests/test_views.py

@@ -0,0 +1,49 @@
+from unittest import TestCase, mock
+from rest_framework.test import APIClient
+
+from api.core.serializers import strategy_id
+
+
+class TestStrategy(object):
+
+    def __init__(self, name, classifier):
+        self.name = name
+        self.classifier = classifier
+
+    def init_params(self):
+        return {}
+
+
+class TestStrategyView(TestCase):
+    strategies = [
+        TestStrategy('Test One', {'stochastic': True, 'memory_depth': 1}),
+        TestStrategy('Test Two', {'stochastic': True, 'memory_depth': 1}),
+        TestStrategy('Test Three', {'stochastic': True, 'memory_depth': 2}),
+        TestStrategy('Test Four', {'stochastic': False, 'memory_depth': 2}),
+        TestStrategy('Test Five', {'stochastic': False, 'memory_depth': 1}),
+    ]
+    strategies_index = {strategy_id(s): s for s in strategies}
+
+    def setUp(self):
+        self.client = APIClient()
+
+    @mock.patch('api.core.views.axl.filtered_strategies')
+    def test_lists_all_strategies(self, filtered_strategies):
+        filtered_strategies.return_value = self.strategies
+        response = self.client.get('/strategies/')
+        self.assertEqual(200, response.status_code)
+        self.assertEqual(5, len(response.data))
+
+    @mock.patch('api.core.views.StrategyViewSet.strategies_index', strategies_index)
+    def test_retrieves_one_strategy(self):
+        response = self.client.get('/strategies/testone/')
+        self.assertEqual(200, response.status_code)
+        self.assertEqual('Test One', response.data['name'])
+
+    @mock.patch('api.core.views.StrategyViewSet.strategies_index', strategies_index)
+    def test_strategy_does_not_exist(self):
+        response = self.client.get('/strategies/notfound/')
+        self.assertEqual(404, response.status_code)
+
+
+

api/core/views.py

@@ -1,4 +1,5 @@
 from distutils.util import strtobool
+from django.http import Http404
 from rest_framework import viewsets
 from rest_framework.response import Response
 import axelrod as axl
@@ -51,6 +52,9 @@ def list(self, request):
         return Response(serializer.data)
 
     def retrieve(self, request, pk=None):
-        strategy = self.strategies_index[pk]
+        try:
+            strategy = self.strategies_index[pk]
+        except KeyError:
+            raise Http404
         serializer = StrategySerializer(strategy, context={'request': request})
         return Response(serializer.data)