test: add additional tests for cgroupns option

See #2930.

Signed-off-by: Milas Bowman <milas.bowman@docker.com>

tests/integration/api_container_test.py

@@ -215,6 +215,20 @@ def test_create_with_mac_address(self):
 
         self.client.kill(id)
 
+    @requires_api_version('1.41')
+    def test_create_with_cgroupns(self):
+        host_config = self.client.create_host_config(cgroupns='private')
+
+        container = self.client.create_container(
+            image=TEST_IMG,
+            command=['sleep', '60'],
+            host_config=host_config,
+        )
+        self.tmp_containers.append(container)
+
+        res = self.client.inspect_container(container)
+        assert 'private' == res['HostConfig']['CgroupnsMode']
+
     def test_group_id_ints(self):
         container = self.client.create_container(
             TEST_IMG, 'id -G',

tests/unit/api_container_test.py

@@ -1069,6 +1069,25 @@ def test_create_container_with_host_config_cpus(self):
         ''')
         assert args[1]['headers'] == {'Content-Type': 'application/json'}
 
+    @requires_api_version('1.41')
+    def test_create_container_with_cgroupns(self):
+        self.client.create_container(
+            image='busybox',
+            command='true',
+            host_config=self.client.create_host_config(
+                cgroupns='private',
+            ),
+        )
+
+        args = fake_request.call_args
+        assert args[0][1] == url_prefix + 'containers/create'
+
+        expected_payload = self.base_create_payload()
+        expected_payload['HostConfig'] = self.client.create_host_config()
+        expected_payload['HostConfig']['CgroupnsMode'] = 'private'
+        assert json.loads(args[1]['data']) == expected_payload
+        assert args[1]['headers'] == {'Content-Type': 'application/json'}
+
 
 class ContainerTest(BaseAPIClientTest):
     def test_list_containers(self):