Remove six usage (2/2)

This repo does not support Python 2 anymore, so we don't need
six for compatibility between Python2 and 3,
convert six usage to Python 3 code.

This changes urllib usage.

mock.patch usage in heat_dashboard/test/tests/api/test_heat.py
is modified to cope with the mix usage of urllib from python3 (in
heat-dashboard) and six.moves.urllib (in heatclient).
In the case of the mix usage, patching urllib.request.urlopen() only
does not work as urllib.request.urlopen() is not called after
resolving a lazy loading in six and the resolved object is
six.moves.urllib.request is called. The previous code depends on
the behavior in heatclient read_url_content() and the method should
be mocked instead. Considering this, mocking in api/test_heat.py
is modified to mock direct methods called in the heat-dashboard code.

Co-Authored-By: Akihiro Motoki <amotoki@gmail.com>
Change-Id: Icf3f889770242b02023fe22c405cfa2d823581a5
Needed-By: https://review.opendev.org/701743

heat_dashboard/api/heat.py

@@ -12,7 +12,7 @@
 
 import contextlib
 
-from six.moves.urllib import request
+from urllib import request
 
 from django.conf import settings
 from oslo_serialization import jsonutils

heat_dashboard/test/tests/api/test_heat.py

@@ -13,7 +13,6 @@
 import io
 
 import mock
-import six
 
 from django.conf import settings
 from django.test.utils import override_settings
@@ -257,8 +256,8 @@ def test_get_template_files_with_template_data(self):
         files = api.heat.get_template_files(template_data=tmpl)[0]
         self.assertEqual(files, expected_files)
 
-    @mock.patch.object(six.moves.urllib.request, 'urlopen')
-    def test_get_template_files(self, mock_request):
+    @mock.patch('heatclient.common.utils.read_url_content')
+    def test_get_template_files(self, mock_read_url_content):
         tmpl = '''
     # comment
 
@@ -276,14 +275,16 @@ def test_get_template_files(self, mock_request):
         expected_files = {u'http://test.example/example': b'echo "test"'}
         url = 'http://test.example/example'
         data = b'echo "test"'
-        mock_request.return_value = io.BytesIO(data)
+        mock_read_url_content.return_value = data
 
         files = api.heat.get_template_files(template_data=tmpl)[0]
         self.assertEqual(files, expected_files)
-        mock_request.assert_called_once_with(url)
+        mock_read_url_content.assert_called_once_with(url)
 
-    @mock.patch.object(six.moves.urllib.request, 'urlopen')
-    def test_get_template_files_with_template_url(self, mock_request):
+    @mock.patch('urllib.request.urlopen')
+    @mock.patch('heatclient.common.utils.read_url_content')
+    def test_get_template_files_with_template_url(self, mock_read_url_content,
+                                                  mock_request):
         url = 'https://test.example/example.yaml'
         data = b'''
     # comment
@@ -301,11 +302,14 @@ def test_get_template_files_with_template_url(self, mock_request):
     '''
         data2 = b'echo "test"'
         expected_files = {'http://test.example/example': b'echo "test"'}
-        mock_request.side_effect = \
-            [io.BytesIO(data), io.BytesIO(data2)]
+        mock_request.return_value = io.BytesIO(data)
+        mock_read_url_content.return_value = data2
 
         files = api.heat.get_template_files(template_url=url)[0]
         self.assertEqual(files, expected_files)
+        mock_request.assert_called_once_with(url)
+        mock_read_url_content.assert_called_once_with(
+            'http://test.example/example')
 
     def test_get_template_files_invalid(self):
         tmpl = '''