fix: correct default series selection

.github/workflows/test.yaml

@@ -54,13 +54,15 @@ jobs:
           - "3.11"
           - "3.12"
           - "3.13"
+          - "3.14.0-alpha.1"
     steps:
       - name: Check out code
         uses: actions/checkout@v4
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python }}
+          allow-prereleases: true
       - name: Install dependencies
         run: pip install tox
       - name: Run unit tests
@@ -84,12 +86,7 @@ jobs:
           - "3.3/stable"
           - "3.4/stable"
           - "3.5/stable"
-          # A bunch of tests fail with juju.errors.JujuError: base: [email protected]/stable
-          # * test_subordinate_units
-          # * test_destroy_unit
-          # * test_ssh
-          # * ...
-          # - "3.6/beta"
+          - "3.6/candidate"
     steps:
       - name: Check out code
         uses: actions/checkout@v4
@@ -149,6 +146,7 @@ jobs:
           - "3.3/stable"
           - "3.4/stable"
           - "3.5/stable"
+          - "3.6/candidate"
     steps:
       - name: Check out code
         uses: actions/checkout@v4

juju/utils.py

@@ -483,7 +483,7 @@ def series_for_charm(requested_series, supported_series):
 
     # use the charm default
     if requested_series == "":
-        return supported_series[-1]
+        return supported_series[0]
 
     for s in supported_series:
         if requested_series == s:

tests/unit/test_utils.py

@@ -66,7 +66,7 @@ def test_model_config(self):
         )
 
     def test_charm_list_series(self):
-        assert series_selector(supported_series=["focal", "jammy"]) == "jammy"
+        assert series_selector(supported_series=["jammy", "focal"]) == "jammy"
 
     def test_return_lts(self):
         assert series_selector() == DEFAULT_SUPPORTED_LTS