refactor cli tests

Signed-off-by: Collins Abitekaniza <[email protected]>

tests/acceptance/cli_test.py

@@ -2229,6 +2229,7 @@ class CLITestCase(DockerClientTestCase):
 
     def test_start_no_containers(self):
         result = self.dispatch(['start'], returncode=1)
+        assert 'failed' in result.stderr
         assert 'No containers to start' in result.stderr
 
     @v2_only()