Remove project.create_containers(), revamp project.recreate_containers()

`recreate_containers` now returns two lists of old+new containers, along
with their services.

fig/project.py

@@ -79,20 +79,22 @@ class Project(object):
             unsorted = [self.get_service(name) for name in service_names]
             return [s for s in self.services if s in unsorted]
 
-    def create_containers(self, service_names=None):
-        """
-        For each service, creates a container if there are none.
-        """
-        for service in self.get_services(service_names):
-            if len(service.containers(stopped=True)) == 0:
-                service.create_container()
-
-    def recreate_containers(self, service_names):
+    def recreate_containers(self, service_names=None):
         """
         For each service, create or recreate their containers.
+        Returns a tuple with two lists. The first is a list of
+        (service, old_container) tuples; the second is a list
+        of (service, new_container) tuples.
         """
+        old = []
+        new = []
+
         for service in self.get_services(service_names):
-            service.recreate_containers()
+            (s_old, s_new) = service.recreate_containers()
+            old += [(service, container) for container in s_old]
+            new += [(service, container) for container in s_new]
+
+        return (old, new)
 
     def start(self, service_names=None, **options):
         for service in self.get_services(service_names):

fig/service.py

@@ -80,7 +80,7 @@ class Service(object):
         """
         old_containers = self.containers(stopped=True)
         if len(old_containers) == 0:
-            return [self.create_container(**override_options)]
+            return ([], [self.create_container(**override_options)])
         else:
             new_containers = []
             for old_container in old_containers:

tests/project_test.py

@@ -42,17 +42,22 @@ class ProjectTest(DockerClientTestCase):
         project = Project('test', [web], self.client)
         self.assertEqual(project.get_service('web'), web)
 
-    def test_create_containers(self):
+    def test_recreate_containers(self):
         web = self.create_service('web')
         db = self.create_service('db')
         project = Project('test', [web, db], self.client)
 
-        project.create_containers(service_names=['web'])
+        old_web_container = web.create_container()
         self.assertEqual(len(web.containers(stopped=True)), 1)
         self.assertEqual(len(db.containers(stopped=True)), 0)
 
-        project.create_containers()
-        self.assertEqual(len(web.containers(stopped=True)), 1)
+        (old, new) = project.recreate_containers()
+        self.assertEqual(old, [(web, old_web_container)])
+        self.assertEqual(len(new), 2)
+        self.assertEqual(new[0][0], web)
+        self.assertEqual(new[1][0], db)
+
+        self.assertEqual(len(web.containers(stopped=True)), 2)
         self.assertEqual(len(db.containers(stopped=True)), 1)
 
     def test_start_stop_kill_remove(self):