Fix a test case that assumes busybox image id.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

tests/integration/service_test.py

@@ -10,6 +10,7 @@ import shutil
 from six import StringIO, text_type
 
 from .testcases import DockerClientTestCase
+from .testcases import pull_busybox
 from compose import __version__
 from compose.const import (
     LABEL_CONTAINER_NUMBER,
@@ -577,8 +578,10 @@ class ServiceTest(DockerClientTestCase):
         })
 
     def test_create_with_image_id(self):
-        # Image id for the current busybox:latest
-        service = self.create_service('foo', image='8c2e06607696')
+        # Get image id for the current busybox:latest
+        pull_busybox(self.client)
+        image_id = self.client.inspect_image('busybox:latest')['Id'][:12]
+        service = self.create_service('foo', image=image_id)
         service.create_container()
 
     def test_scale(self):

tests/integration/testcases.py

@@ -1,5 +1,8 @@
 from __future__ import unicode_literals
 from __future__ import absolute_import
+
+from docker import errors
+
 from compose.service import Service
 from compose.config import ServiceLoader
 from compose.const import LABEL_PROJECT
@@ -8,6 +11,13 @@ from compose.progress_stream import stream_output
 from .. import unittest
 
 
+def pull_busybox(client):
+    try:
+        client.inspect_image('busybox:latest')
+    except errors.APIError:
+        client.pull('busybox:latest', stream=False)
+
+
 class DockerClientTestCase(unittest.TestCase):
     @classmethod
     def setUpClass(cls):