tests: Disallow use of util.subp except for where needed.

In many cases, cloud-init uses 'util.subp' to run a subprocess.
This is not really desirable in our unit tests as it makes the tests
dependent upon existance of those utilities.

The change here is to modify the base test case class (CiTestCase) to
raise exception any time subp is called.  Then, fix all callers.
For cases where subp is necessary or actually desired, we can use it
via
  a.) context hander CiTestCase.allow_subp(value)
  b.) class level self.allowed_subp = value

Both cases the value is a list of acceptable executable names that
will be called (essentially argv[0]).

Some cleanups in AltCloud were done as the code was being updated.

1 files changed, 6 insertions, 2 deletions

diff --git a/tests/unittests/test_handler/test_handler_resizefs.py b/tests/unittests/test_handler/test_handler_resizefs.py
index f92175fd..feca56c2 100644
--- a/tests/unittests/test_handler/test_handler_resizefs.py
+++ b/tests/unittests/test_handler/test_handler_resizefs.py
@@ -150,10 +150,12 @@ class TestResizefs(CiTestCase):
         self.assertEqual(('growfs', '-y', devpth),
                          _resize_ufs(mount_point, devpth))
 
+    @mock.patch('cloudinit.util.is_container', return_value=False)
     @mock.patch('cloudinit.util.get_mount_info')
     @mock.patch('cloudinit.util.get_device_info_from_zpool')
     @mock.patch('cloudinit.util.parse_mount')
-    def test_handle_zfs_root(self, mount_info, zpool_info, parse_mount):
+    def test_handle_zfs_root(self, mount_info, zpool_info, parse_mount,
+                             is_container):
         devpth = 'vmzroot/ROOT/freebsd'
         disk = 'gpt/system'
         fs_type = 'zfs'
@@ -354,8 +356,10 @@ class TestMaybeGetDevicePathAsWritableBlock(CiTestCase):
             ('btrfs', 'filesystem', 'resize', 'max', '/'),
             _resize_btrfs("/", "/dev/sda1"))
 
+    @mock.patch('cloudinit.util.is_container', return_value=True)
     @mock.patch('cloudinit.util.is_FreeBSD')
-    def test_maybe_get_writable_device_path_zfs_freebsd(self, freebsd):
+    def test_maybe_get_writable_device_path_zfs_freebsd(self, freebsd,
+                                                        m_is_container):
         freebsd.return_value = True
         info = 'dev=gpt/system mnt_point=/ path=/'
         devpth = maybe_get_writable_device_path('gpt/system', info, LOG)