add api feature gates (+ reviews shim as example case)

src/olympia/api/tests/test_utils.py

@@ -0,0 +1,35 @@
+from django.test import override_settings
+
+from rest_framework.test import APIRequestFactory
+
+from olympia.api.utils import is_gate_active
+
+factory = APIRequestFactory()
+
+
+@override_settings(DRF_API_GATES={'v1': None, 'v2': {'foo'}})
+def test_is_gate_active():
+    request = factory.get('/')
+
+    assert not is_gate_active(request, 'foo')
+
+    request.version = 'v2'
+
+    assert is_gate_active(request, 'foo')
+
+
+@override_settings(DRF_API_GATES={
+    'v1': None, 'v2': {'foo'}, 'v3': {'baa'}})
+def test_is_gate_active_explicit_upgrades():
+    # Test that we're not implicitly upgrading feature gates
+    request = factory.get('/')
+
+    assert not is_gate_active(request, 'baa')
+
+    request.version = 'v2'
+
+    assert not is_gate_active(request, 'baa')
+
+    request.version = 'v3'
+
+    assert is_gate_active(request, 'baa')

src/olympia/api/utils.py

@@ -0,0 +1,14 @@
+from django.conf import settings
+
+
+def is_gate_active(request, name):
+    """Check if a specific gate is active for the current API version.
+    Note that `request` has to be a :class:`~rest_framework.request.Request`
+    object that has `version` attached.
+    We're not examining Django request objects.
+    """
+    gates = settings.DRF_API_GATES.get(getattr(request, 'version', None), None)
+    if not gates:
+        return False
+
+    return name in gates

src/olympia/lib/settings_base.py

@@ -1673,6 +1673,14 @@ def get_redis_settings(uri):
     'JWT_ALLOW_REFRESH': False,
 }
 
+DRF_API_GATES = {
+    'v3': (
+        'ratings-rating-shim',
+    ),
+    'v4': (
+    )
+}
+
 REST_FRAMEWORK = {
     # Set this because the default is to also include:
     #   'rest_framework.renderers.BrowsableAPIRenderer'

src/olympia/ratings/serializers.py

@@ -9,6 +9,7 @@
 
 from olympia.accounts.serializers import BaseUserSerializer
 from olympia.addons.serializers import SimpleVersionSerializer
+from olympia.api.utils import is_gate_active
 from olympia.ratings.forms import RatingForm
 from olympia.ratings.models import Rating
 from olympia.versions.models import Version
@@ -135,13 +136,21 @@ def to_internal_value(self, data):
 
 class RatingSerializer(BaseRatingSerializer):
     reply = RatingSerializerReply(read_only=True)
-    rating = serializers.IntegerField(min_value=1, max_value=5)
     version = RatingVersionSerializer()
+    score = serializers.IntegerField(min_value=1, max_value=5, source='rating')
 
     class Meta:
         model = Rating
         fields = BaseRatingSerializer.Meta.fields + (
-            'rating', 'reply', 'version')
+            'score', 'reply', 'version')
+
+    def __init__(self, *args, **kwargs):
+        super(RatingSerializer, self).__init__(*args, **kwargs)
+        request = kwargs.get('context', {}).get('request')
+        if request and is_gate_active(request, 'ratings-rating-shim'):
+            score_field = self.fields.pop('score')
+            score_field.source = None  # drf complains if we specifiy source.
+            self.fields['rating'] = score_field
 
     def validate_version(self, version):
         if self.partial:

src/olympia/ratings/tests/test_serializers.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+from django.test import override_settings
+
 from mock import Mock
 from rest_framework.test import APIRequestFactory
 
@@ -44,7 +46,7 @@ def test_basic(self):
         assert result['title'] == unicode(self.rating.title)
         assert result['previous_count'] == int(self.rating.previous_count)
         assert result['is_latest'] == self.rating.is_latest
-        assert result['rating'] == int(self.rating.rating)
+        assert result['score'] == int(self.rating.rating)
         assert result['reply'] is None
         assert result['user'] == {
             'id': self.user.pk,
@@ -61,6 +63,20 @@ def test_basic(self):
         result = self.serialize()
         assert result['version'] is None
 
+    @override_settings(DRF_API_GATES={None: ('ratings-rating-shim',)})
+    def test_ratings_score_is_rating_with_gate(self):
+        addon = addon_factory()
+        self.view.get_addon_object.return_value = addon
+        self.rating = Rating.objects.create(
+            addon=addon, user=self.user, rating=4,
+            version=addon.current_version, body=u'This is my rëview. Like ît?',
+            title=u'My Review Titlé')
+
+        result = self.serialize()
+
+        assert result['id'] == self.rating.pk
+        assert result['rating'] == int(self.rating.rating)
+
     def test_url_for_yourself(self):
         addon = addon_factory()
         self.view.get_addon_object.return_value = addon