Jormungandr: use max_nb_journeys in isochrone

close hove-io#356 as count fill max_nb_journeys when provided

source/jormungandr/jormungandr/scenarios/default.py

@@ -452,6 +452,11 @@ def isochrone(self, request, instance):
         req.journeys.streetnetwork_params.destination_mode = self.destination_modes[0]
         resp = instance.send_and_receive(req)
 
+        if not request['debug']:
+            # on isochrone we can filter the number of max journeys
+            if request["max_nb_journeys"] and len(resp.journeys) > request["max_nb_journeys"]:
+                del resp.journeys[request["max_nb_journeys"]:]
+
         return resp
 
     def _remove_not_long_enough_fallback(self, resp, instance):

source/jormungandr/tests/isochrone_tests.py

@@ -100,10 +100,17 @@ def test_reverse_isochrone_coord_clockwise(self):
         assert error_code == 404
         assert normal_response['error']['message'] == 'reverse isochrone works only for anti-clockwise request'
 
-
     def test_isochrone_non_clockwise(self):
         q = "v1/coverage/basic_routing_test/journeys?datetime=20120614T080000&from=A&datetime_represents=arrival"
         normal_response, error_code = self.query_no_assert(q)
 
         assert error_code == 404
         assert normal_response['error']['message'] == 'isochrone works only for clockwise request'
+
+    def test_isochrone_count(self):
+        query = "v1/coverage/basic_routing_test/stop_points/A/journeys?max_duration=25500&datetime=20120614T080000"
+        response = self.query(query)
+        assert len(response["journeys"]) == 2
+        query += "&count=1"
+        response = self.query(query)
+        assert len(response["journeys"]) == 1