Use docker context interface from docker-py

Signed-off-by: Anca Iordache <anca.iordache@docker.com>

tests/acceptance/context_test.py

@@ -0,0 +1,48 @@
+# -*- coding: utf-8 -*-
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import os
+import shutil
+import unittest
+
+from docker import ContextAPI
+
+from tests.acceptance.cli_test import dispatch
+
+
+class ContextTestCase(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.docker_dir = os.path.join(os.environ.get("HOME", "/tmp"), '.docker')
+        if not os.path.exists(cls.docker_dir):
+            os.makedirs(cls.docker_dir)
+        f = open(os.path.join(cls.docker_dir, "config.json"), "w")
+        f.write("{}")
+        f.close()
+        cls.docker_config = os.path.join(cls.docker_dir, "config.json")
+        os.environ['DOCKER_CONFIG'] = cls.docker_config
+        ContextAPI.create_context("testcontext", host="tcp://doesnotexist:8000")
+
+    @classmethod
+    def tearDownClass(cls):
+        shutil.rmtree(cls.docker_dir, ignore_errors=True)
+
+    def setUp(self):
+        self.base_dir = 'tests/fixtures/simple-composefile'
+        self.override_dir = None
+
+    def dispatch(self, options, project_options=None, returncode=0, stdin=None):
+        return dispatch(self.base_dir, options, project_options, returncode, stdin)
+
+    def test_help(self):
+        result = self.dispatch(['help'], returncode=0)
+        assert '-c, --context NAME' in result.stdout
+
+    def test_fail_on_both_host_and_context_opt(self):
+        result = self.dispatch(['-H', 'unix://', '-c', 'default', 'up'], returncode=1)
+        assert '-H, --host and -c, --context are mutually exclusive' in result.stderr
+
+    def test_fail_run_on_inexistent_context(self):
+        result = self.dispatch(['-c', 'testcontext', 'up', '-d'], returncode=1)
+        assert "Couldn't connect to Docker daemon" in result.stderr