testing: monkeypatch system_info call in unit tests (SC-533) (#1117)

testing: monkeypatch system_info call in unit tests

system_info can make calls that read or write from the filesystem, which
should require special mocking. It is also decorated with 'lru_cache',
which means test authors often don't realize they need to be mocking.
Also, we don't actually want the results from the user's local
machine, so monkeypatching it across all tests should be reasonable.

Additionally, moved some of 'system_info` into a helper function to
reduce the surface area of the monkeypatch, added tests for the new
function (and fixed a bug as a result), and removed related mocks that
should be no longer needed.

1 files changed, 14 insertions, 13 deletions

diff --git a/tests/unittests/test_handler/test_handler_ntp.py b/tests/unittests/test_handler/test_handler_ntp.py
index b9e2ba57..b34a18cb 100644
--- a/tests/unittests/test_handler/test_handler_ntp.py
+++ b/tests/unittests/test_handler/test_handler_ntp.py
@@ -37,8 +37,6 @@ class TestNtp(FilesystemMockingTestCase):
         self.new_root = self.tmp_dir()
         self.add_patch('cloudinit.util.system_is_snappy', 'm_snappy')
         self.m_snappy.return_value = False
-        self.add_patch('cloudinit.util.system_info', 'm_sysinfo')
-        self.m_sysinfo.return_value = {'dist': ('Distro', '99.1', 'Codename')}
         self.new_root = self.reRoot()
         self._get_cloud = partial(
             get_cloud,
@@ -510,35 +508,38 @@ class TestNtp(FilesystemMockingTestCase):
 
             self.assertEqual(expected_content, util.load_file(confpath))
 
-    def test_opensuse_picks_chrony(self):
+    @mock.patch('cloudinit.util.system_info')
+    def test_opensuse_picks_chrony(self, m_sysinfo):
         """Test opensuse picks chrony or ntp on certain distro versions"""
         #  < 15.0  => ntp
-        self.m_sysinfo.return_value = {'dist':
-                                       ('openSUSE', '13.2', 'Harlequin')}
+        m_sysinfo.return_value = {
+            'dist': ('openSUSE', '13.2', 'Harlequin')
+        }
         mycloud = self._get_cloud('opensuse')
         expected_client = mycloud.distro.preferred_ntp_clients[0]
         self.assertEqual('ntp', expected_client)
 
         #  >= 15.0 and  not openSUSE => chrony
-        self.m_sysinfo.return_value = {'dist':
-                                       ('SLES', '15.0',
-                                        'SUSE Linux Enterprise Server 15')}
+        m_sysinfo.return_value = {
+            'dist': ('SLES', '15.0', 'SUSE Linux Enterprise Server 15')
+        }
         mycloud = self._get_cloud('sles')
         expected_client = mycloud.distro.preferred_ntp_clients[0]
         self.assertEqual('chrony', expected_client)
 
         #  >= 15.0 and  openSUSE and ver != 42  => chrony
-        self.m_sysinfo.return_value = {'dist': ('openSUSE Tumbleweed',
-                                                '20180326',
-                                                'timbleweed')}
+        m_sysinfo.return_value = {
+            'dist': ('openSUSE Tumbleweed', '20180326', 'timbleweed')
+        }
         mycloud = self._get_cloud('opensuse')
         expected_client = mycloud.distro.preferred_ntp_clients[0]
         self.assertEqual('chrony', expected_client)
 
-    def test_ubuntu_xenial_picks_ntp(self):
+    @mock.patch('cloudinit.util.system_info')
+    def test_ubuntu_xenial_picks_ntp(self, m_sysinfo):
         """Test Ubuntu picks ntp on xenial release"""
 
-        self.m_sysinfo.return_value = {'dist': ('Ubuntu', '16.04', 'xenial')}
+        m_sysinfo.return_value = {'dist': ('Ubuntu', '16.04', 'xenial')}
         mycloud = self._get_cloud('ubuntu')
         expected_client = mycloud.distro.preferred_ntp_clients[0]
         self.assertEqual('ntp', expected_client)