Add utility to parse base argument

Author: cderici

juju/utils.py

@@ -10,6 +10,7 @@
 import zipfile
 
 from . import jasyncio, origin, errors
+from .client import client
 
 
 async def execute_process(*cmd, log=None):
@@ -403,3 +404,15 @@ def base_channel_to_series(channel):
     :return: str series (e.g. focal)
     """
     return get_version_series(origin.Channel.parse(channel).track)
+
+
+def parse_base_arg(base):
+    """Parses a given base into a Client.Base object
+    :param base str : The base to deploy a charm (e.g. ubuntu@22.04)
+    """
+    client.CharmBase()
+    if type(base) != str or "@" not in base:
+        raise errors.JujuError("expected base string to contain os and channel separated by '@'")
+
+    name, channel = base.split('@')
+    return client.Base(name=name, channel=channel)

tests/unit/test_utils.py

@@ -1,6 +1,7 @@
 import unittest
 
-from juju.utils import juju_config_dir, juju_ssh_key_paths
+from juju.utils import juju_config_dir, juju_ssh_key_paths, parse_base_arg
+from juju.client import client
 
 
 class TestDirResolve(unittest.TestCase):
@@ -12,3 +13,9 @@ def test_juju_ssh_key_paths(self):
         public, private = juju_ssh_key_paths()
         assert public.endswith('ssh/juju_id_rsa.pub')
         assert private.endswith('ssh/juju_id_rsa')
+
+    def test_parse_base_arg(self):
+        base = parse_base_arg('ubuntu@22.04')
+        assert isinstance(base, client.Base)
+        assert base.name == 'ubuntu'
+        assert base.channel == '22.04'