archlinux: Fix bug with empty dns, do not render 'lo' devices.

If no dns nameservers were provided a stack trace would occur.
The changes here add some unit tests for the arch distro.

Also avoids rendering an 'lo' interface.

LP: #1663045
LP: #1706593

2 files changed, 66 insertions, 0 deletions

diff --git a/tests/unittests/test_distros/__init__.py b/tests/unittests/test_distros/__init__.py
index e69de29b..5394aa56 100644
--- a/tests/unittests/test_distros/__init__.py
+++ b/tests/unittests/test_distros/__init__.py
@@ -0,0 +1,21 @@
+# This file is part of cloud-init. See LICENSE file for license information.
+import copy
+
+from cloudinit import distros
+from cloudinit import helpers
+from cloudinit import settings
+
+
+def _get_distro(dtype, system_info=None):
+    """Return a Distro class of distro 'dtype'.
+
+    cfg is format of CFG_BUILTIN['system_info'].
+
+    example: _get_distro("debian")
+    """
+    if system_info is None:
+        system_info = copy.deepcopy(settings.CFG_BUILTIN['system_info'])
+    system_info['distro'] = dtype
+    paths = helpers.Paths(system_info['paths'])
+    distro_cls = distros.fetch(dtype)
+    return distro_cls(dtype, system_info, paths)
diff --git a/tests/unittests/test_distros/test_arch.py b/tests/unittests/test_distros/test_arch.py
new file mode 100644
index 00000000..3d4c9a70
--- /dev/null
+++ b/tests/unittests/test_distros/test_arch.py
@@ -0,0 +1,45 @@
+# This file is part of cloud-init. See LICENSE file for license information.
+
+from cloudinit.distros.arch import _render_network
+from cloudinit import util
+
+from ..helpers import (CiTestCase, dir2dict)
+
+from . import _get_distro
+
+
+class TestArch(CiTestCase):
+
+    def test_get_distro(self):
+        distro = _get_distro("arch")
+        hostname = "myhostname"
+        hostfile = self.tmp_path("hostfile")
+        distro._write_hostname(hostname, hostfile)
+        self.assertEqual(hostname + "\n", util.load_file(hostfile))
+
+
+class TestRenderNetwork(CiTestCase):
+    def test_basic_static(self):
+        """Just the most basic static config.
+
+        note 'lo' should not be rendered as an interface."""
+        entries = {'eth0': {'auto': True,
+                            'dns-nameservers': ['8.8.8.8'],
+                            'bootproto': 'static',
+                            'address': '10.0.0.2',
+                            'gateway': '10.0.0.1',
+                            'netmask': '255.255.255.0'},
+                   'lo': {'auto': True}}
+        target = self.tmp_dir()
+        devs = _render_network(entries, target=target)
+        files = dir2dict(target, prefix=target)
+        self.assertEqual(['eth0'], devs)
+        self.assertEqual(
+            {'/etc/netctl/eth0': '\n'.join([
+                "Address=10.0.0.2/255.255.255.0",
+                "Connection=ethernet",
+                "DNS=('8.8.8.8')",
+                "Gateway=10.0.0.1",
+                "IP=static",
+                "Interface=eth0", ""]),
+             '/etc/resolv.conf': 'nameserver 8.8.8.8\n'}, files)