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.)

1 files changed, 4 insertions, 4 deletions

diff --git a/tests/cloud_tests/testcases/__init__.py b/tests/cloud_tests/testcases/__init__.py
index 6bb39f77..e8c371ca 100644
--- a/tests/cloud_tests/testcases/__init__.py
+++ b/tests/cloud_tests/testcases/__init__.py
@@ -4,7 +4,7 @@
 
 import importlib
 import inspect
-import unittest2
+import unittest
 
 from cloudinit.util import read_conf
 
@@ -48,7 +48,7 @@ def get_test_class(test_name, test_data, test_conf):
 
         def __str__(self):
             return "%s (%s)" % (self._testMethodName,
-                                unittest2.util.strclass(self._realclass))
+                                unittest.util.strclass(self._realclass))
 
         @classmethod
         def setUpClass(cls):
@@ -62,9 +62,9 @@ def get_suite(test_name, data, conf):
 
     @return_value: a test suite
     """
-    suite = unittest2.TestSuite()
+    suite = unittest.TestSuite()
     suite.addTest(
-        unittest2.defaultTestLoader.loadTestsFromTestCase(
+        unittest.defaultTestLoader.loadTestsFromTestCase(
             get_test_class(test_name, data, conf)))
     return suite