Add base_channel_to_series and update test

Author: cderici

juju/application.py

@@ -371,8 +371,7 @@ async def get_series(self):
         appGetResults = (await app_facade.Get(application=self.name))
         if self._facade_version() >= 15:
             base_channel = appGetResults.base.channel
-            track = Channel.parse(base_channel).track
-            return utils.get_version_series(track)
+            return utils.base_channel_to_series(base_channel)
         return appGetResults.series
 
     async def get_config(self):

juju/utils.py

@@ -382,3 +382,11 @@ def get_local_charm_base(series, channel_from_arg, charm_metadata,
                                charm_path)
 
     return baseCls(channel_for_base, os_name_for_base)
+
+def base_channel_to_series(channel):
+    """
+
+    :param str channel: is track/risk (e.g. 20.04/stable)
+    :return: str series (e.g. focal)
+    """
+    return get_version_series(origin.Channel.parse(channel).track)

tests/integration/test_model.py

@@ -16,7 +16,7 @@
 from juju.client import client
 from juju.errors import JujuError, JujuModelError, JujuUnitError, JujuConnectionError
 from juju.model import Model, ModelObserver
-from juju.utils import block_until, run_with_interrupt, wait_for_bundle
+from juju.utils import block_until, run_with_interrupt, wait_for_bundle, base_channel_to_series
 
 from .. import base
 
@@ -315,11 +315,19 @@ async def test_deploy_channels_revs(event_loop):
 @pytest.mark.asyncio
 async def test_deploy_from_ch_with_series(event_loop):
     charm = 'ch:ubuntu'
-    for series in ['xenial', 'bionic', 'focal']:
+    for series in ['focal']:
         async with base.CleanModel() as model:
             app_name = "ubuntu-{}".format(series)
             await model.deploy(charm, application_name=app_name, series=series)
-            assert (await model.get_status())["applications"][app_name]["series"] == series
+            status = (await model.get_status())
+            app_status = status["applications"][app_name]
+
+            if 'series' in app_status.serialize():
+                s = app_status['series']
+            else:
+                # If there's no series, we should have a base
+                s = base_channel_to_series(app_status.base.channel)
+            assert s == series
 
 
 @base.bootstrapped