Return tuple instead of dict in exec_run

Signed-off-by: Joffrey F <joffrey@docker.com>

docker/models/containers.py

@@ -150,13 +150,13 @@ class Container(Model):
             workdir (str): Path to working directory for this exec session
 
         Returns:
-            dict:
+            (tuple): A tuple of (exit_code, output)
+                exit_code: (int):
+                    Exit code for the executed command
                 output: (generator or str):
                     If ``stream=True``, a generator yielding response chunks.
                     If ``socket=True``, a socket object for the connection.
                     A string containing response data otherwise.
-                exit_code: (int):
-                    Exited code of execution
 
         Raises:
             :py:class:`docker.errors.APIError`
@@ -173,10 +173,7 @@ class Container(Model):
         exit_code = 0
         if stream is False:
             exit_code = self.client.api.exec_inspect(resp['Id'])['ExitCode']
-        return {
-            'exit_code': exit_code,
-            'output': exec_output
-        }
+        return (exit_code, exec_output)
 
     def export(self):
         """

tests/integration/models_containers_test.py

@@ -189,8 +189,8 @@ class ContainerTest(BaseIntegrationTest):
         )
         self.tmp_containers.append(container.id)
         exec_output = container.exec_run("cat /test")
-        assert exec_output["output"] == b"hello\n"
-        assert exec_output["exit_code"] == 0
+        assert exec_output[0] == 0
+        assert exec_output[1] == b"hello\n"
 
     def test_exec_run_failed(self):
         client = docker.from_env(version=TEST_API_VERSION)
@@ -199,7 +199,7 @@ class ContainerTest(BaseIntegrationTest):
         )
         self.tmp_containers.append(container.id)
         exec_output = container.exec_run("docker ps")
-        assert exec_output["exit_code"] == 126
+        assert exec_output[0] == 126
 
     def test_kill(self):
         client = docker.from_env(version=TEST_API_VERSION)

tests/unit/models_containers_test.py

@@ -400,13 +400,15 @@ class ContainerTest(unittest.TestCase):
         client.api.exec_start.assert_called_with(
             FAKE_EXEC_ID, detach=False, tty=False, stream=True, socket=False
         )
+
+    def test_exec_run_failure(self):
+        client = make_fake_client()
+        container = client.containers.get(FAKE_CONTAINER_ID)
         container.exec_run("docker ps", privileged=True, stream=False)
         client.api.exec_create.assert_called_with(
             FAKE_CONTAINER_ID, "docker ps", stdout=True, stderr=True,
-            stdin=False, tty=False, privileged=True, user='', environment=None
-        )
-        client.api.exec_start.assert_called_with(
-            FAKE_EXEC_ID, detach=False, tty=False, stream=False, socket=False
+            stdin=False, tty=False, privileged=True, user='', environment=None,
+            workdir=None
         )
         client.api.exec_start.assert_called_with(
             FAKE_EXEC_ID, detach=False, tty=False, stream=False, socket=False