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.)

2 files changed, 6 insertions, 6 deletions

diff --git a/cloudinit/net/tests/test_dhcp.py b/cloudinit/net/tests/test_dhcp.py
index c3fa1e04..bc7bef45 100644
--- a/cloudinit/net/tests/test_dhcp.py
+++ b/cloudinit/net/tests/test_dhcp.py
@@ -62,7 +62,7 @@ class TestParseDHCPLeasesFile(CiTestCase):
             {'interface': 'wlp3s0', 'fixed-address': '192.168.2.74',
              'subnet-mask': '255.255.255.0', 'routers': '192.168.2.1'}]
         write_file(lease_file, content)
-        self.assertItemsEqual(expected, parse_dhcp_lease_file(lease_file))
+        self.assertCountEqual(expected, parse_dhcp_lease_file(lease_file))
 
 
 class TestDHCPRFC3442(CiTestCase):
@@ -88,7 +88,7 @@ class TestDHCPRFC3442(CiTestCase):
              'renew': '4 2017/07/27 18:02:30',
              'expire': '5 2017/07/28 07:08:15'}]
         write_file(lease_file, content)
-        self.assertItemsEqual(expected, parse_dhcp_lease_file(lease_file))
+        self.assertCountEqual(expected, parse_dhcp_lease_file(lease_file))
 
     def test_parse_lease_finds_classless_static_routes(self):
         """
@@ -114,7 +114,7 @@ class TestDHCPRFC3442(CiTestCase):
              'renew': '4 2017/07/27 18:02:30',
              'expire': '5 2017/07/28 07:08:15'}]
         write_file(lease_file, content)
-        self.assertItemsEqual(expected, parse_dhcp_lease_file(lease_file))
+        self.assertCountEqual(expected, parse_dhcp_lease_file(lease_file))
 
     @mock.patch('cloudinit.net.dhcp.EphemeralIPv4Network')
     @mock.patch('cloudinit.net.dhcp.maybe_perform_dhcp_discovery')
@@ -324,7 +324,7 @@ class TestDHCPDiscoveryClean(CiTestCase):
         """)
         write_file(self.tmp_path('dhcp.leases', tmpdir), lease_content)
 
-        self.assertItemsEqual(
+        self.assertCountEqual(
             [{'interface': 'eth9', 'fixed-address': '192.168.2.74',
               'subnet-mask': '255.255.255.0', 'routers': '192.168.2.1'}],
             dhcp_discovery(dhclient_script, 'eth9', tmpdir))
@@ -389,7 +389,7 @@ class TestDHCPDiscoveryClean(CiTestCase):
         write_file(pid_file, "%d\n" % my_pid)
         m_getppid.return_value = 1  # Indicate that dhclient has daemonized
 
-        self.assertItemsEqual(
+        self.assertCountEqual(
             [{'interface': 'eth9', 'fixed-address': '192.168.2.74',
               'subnet-mask': '255.255.255.0', 'routers': '192.168.2.1'}],
             dhcp_discovery(dhclient_script, 'eth9', tmpdir))
diff --git a/cloudinit/net/tests/test_init.py b/cloudinit/net/tests/test_init.py
index 32e70b4c..835ed807 100644
--- a/cloudinit/net/tests/test_init.py
+++ b/cloudinit/net/tests/test_init.py
@@ -397,7 +397,7 @@ class TestGetDeviceList(CiTestCase):
         """get_devicelist returns a directory listing for SYS_CLASS_NET."""
         write_file(os.path.join(self.sysdir, 'eth0', 'operstate'), 'up')
         write_file(os.path.join(self.sysdir, 'eth1', 'operstate'), 'up')
-        self.assertItemsEqual(['eth0', 'eth1'], net.get_devicelist())
+        self.assertCountEqual(['eth0', 'eth1'], net.get_devicelist())
 
 
 class TestGetInterfaceMAC(CiTestCase):