cloudinit: drop dependencies on unittest2 and contextlib2 (#322)

These libraries provide backports of Python 3's stdlib components to Python 2. As we only support Python 3, we can simply use the stdlib now. This pull request does the following:

* removes some unneeded compatibility code for the old spelling of `assertRaisesRegex`
* replaces invocations of the Python 2-only `assertItemsEqual` with its new name, `assertCountEqual`
* replaces all usage of `unittest2` with `unittest`
* replaces all usage of `contextlib2` with `contextlib`
* drops `unittest2` and `contextlib2` from requirements files and tox.ini

It also rewrites some `test_azure` helpers to use bare asserts. We were seeing a strange error in xenial builds of this branch which appear to be stemming from the AssertionError that pytest produces being _different_ from the standard AssertionError.  This means that the modified helpers weren't behaving correctly, because they weren't catching AssertionErrors as one would expect. (I believe this is related, in some way, to https://github.com/pytest-dev/pytest/issues/645, but the only version of pytest where we're affected is so far in the past that it's not worth pursuing it any further as we have a workaround.)

3 files changed, 13 insertions, 13 deletions

diff --git a/tests/unittests/test_datasource/test_azure.py b/tests/unittests/test_datasource/test_azure.py
index 2c6aa44d..2f8561cb 100644
--- a/tests/unittests/test_datasource/test_azure.py
+++ b/tests/unittests/test_datasource/test_azure.py
@@ -528,14 +528,14 @@ scbus-1 on xpt0 bus 0
 
         def tags_exists(x, y):
             for tag in x.keys():
-                self.assertIn(tag, y)
+                assert tag in y
             for tag in y.keys():
-                self.assertIn(tag, x)
+                assert tag in x
 
         def tags_equal(x, y):
             for x_val in x.values():
                 y_val = y.get(x_val.tag)
-                self.assertEqual(x_val.text, y_val.text)
+                assert x_val.text == y_val.text
 
         old_cnt = create_tag_index(oxml)
         new_cnt = create_tag_index(nxml)
@@ -649,7 +649,7 @@ scbus-1 on xpt0 bus 0
 
         crawled_metadata = dsrc.crawl_metadata()
 
-        self.assertItemsEqual(
+        self.assertCountEqual(
             crawled_metadata.keys(),
             ['cfg', 'files', 'metadata', 'userdata_raw'])
         self.assertEqual(crawled_metadata['cfg'], expected_cfg)
diff --git a/tests/unittests/test_datasource/test_azure_helper.py b/tests/unittests/test_datasource/test_azure_helper.py
index 007df09f..6344b0bb 100644
--- a/tests/unittests/test_datasource/test_azure_helper.py
+++ b/tests/unittests/test_datasource/test_azure_helper.py
@@ -1,7 +1,7 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 
 import os
-import unittest2
+import unittest
 from textwrap import dedent
 
 from cloudinit.sources.helpers import azure as azure_helper
@@ -332,7 +332,7 @@ class TestOpenSSLManagerActions(CiTestCase):
         path = 'tests/data/azure'
         return os.path.join(path, name)
 
-    @unittest2.skip("todo move to cloud_test")
+    @unittest.skip("todo move to cloud_test")
     def test_pubkey_extract(self):
         cert = load_file(self._data_file('pubkey_extract_cert'))
         good_key = load_file(self._data_file('pubkey_extract_ssh_key'))
@@ -344,7 +344,7 @@ class TestOpenSSLManagerActions(CiTestCase):
         fingerprint = sslmgr._get_fingerprint_from_cert(cert)
         self.assertEqual(good_fingerprint, fingerprint)
 
-    @unittest2.skip("todo move to cloud_test")
+    @unittest.skip("todo move to cloud_test")
     @mock.patch.object(azure_helper.OpenSSLManager, '_decrypt_certs_from_xml')
     def test_parse_certificates(self, mock_decrypt_certs):
         """Azure control plane puts private keys as well as certificates
diff --git a/tests/unittests/test_datasource/test_smartos.py b/tests/unittests/test_datasource/test_smartos.py
index 62084de5..0f0b42bb 100644
--- a/tests/unittests/test_datasource/test_smartos.py
+++ b/tests/unittests/test_datasource/test_smartos.py
@@ -22,7 +22,7 @@ import os.path
 import re
 import signal
 import stat
-import unittest2
+import unittest
 import uuid
 
 from cloudinit import serial
@@ -1095,11 +1095,11 @@ class TestNetworkConversion(CiTestCase):
         self.assertEqual(expected, found)
 
 
-@unittest2.skipUnless(get_smartos_environ() == SMARTOS_ENV_KVM,
-                      "Only supported on KVM and bhyve guests under SmartOS")
-@unittest2.skipUnless(os.access(SERIAL_DEVICE, os.W_OK),
-                      "Requires write access to " + SERIAL_DEVICE)
-@unittest2.skipUnless(HAS_PYSERIAL is True, "pyserial not available")
+@unittest.skipUnless(get_smartos_environ() == SMARTOS_ENV_KVM,
+                     "Only supported on KVM and bhyve guests under SmartOS")
+@unittest.skipUnless(os.access(SERIAL_DEVICE, os.W_OK),
+                     "Requires write access to " + SERIAL_DEVICE)
+@unittest.skipUnless(HAS_PYSERIAL is True, "pyserial not available")
 class TestSerialConcurrency(CiTestCase):
     """
        This class tests locking on an actual serial port, and as such can only