Refactor migration logic

- Rename `migration` module to `legacy` to make its legacy-ness explicit

- Move `check_for_legacy_containers` into `legacy` module

- Fix migration test so it can be run in isolation

Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>

tests/integration/legacy_test.py

@@ -0,0 +1,30 @@
+import mock
+
+from compose import legacy
+from compose.project import Project
+from .testcases import DockerClientTestCase
+
+
+class ProjectTest(DockerClientTestCase):
+
+    def test_migration_to_labels(self):
+        services = [
+            self.create_service('web'),
+            self.create_service('db'),
+        ]
+
+        project = Project('composetest', services, self.client)
+
+        for service in services:
+            service.ensure_image_exists()
+            self.client.create_container(
+                name='{}_{}_1'.format(project.name, service.name),
+                **service.options
+            )
+
+        with mock.patch.object(legacy, 'log', autospec=True) as mock_log:
+            self.assertEqual(project.containers(stopped=True), [])
+            self.assertEqual(mock_log.warn.call_count, 2)
+
+        legacy.migrate_project_to_labels(project)
+        self.assertEqual(len(project.containers(stopped=True)), 2)

tests/integration/migration_test.py

@@ -1,23 +0,0 @@
-import mock
-
-from compose import service, migration
-from compose.project import Project
-from .testcases import DockerClientTestCase
-
-
-class ProjectTest(DockerClientTestCase):
-
-    def test_migration_to_labels(self):
-        web = self.create_service('web')
-        db = self.create_service('db')
-        project = Project('composetest', [web, db], self.client)
-
-        self.client.create_container(name='composetest_web_1', **web.options)
-        self.client.create_container(name='composetest_db_1', **db.options)
-
-        with mock.patch.object(service, 'log', autospec=True) as mock_log:
-            self.assertEqual(project.containers(stopped=True), [])
-            self.assertEqual(mock_log.warn.call_count, 2)
-
-        migration.migrate_project_to_labels(project)
-        self.assertEqual(len(project.containers(stopped=True)), 2)