test: update the smoke test series/bases (#1318)

A collection of fixes for the smoke test:

* Update the smoke test charm to use the preferred "import ops" style.
* Fix tox to use "allowlist_externals" rather than
"whitelist_externals", which doesn't work in recent versions of tox.
* Remove a bash comment in the tox smoke env - this didn't really add
much value and on my system failed (I think tox believed everything
after the `#` was a comment in tox, rather than in the bash statement)
* Drop support for bionic (18.04) and xenial (16.04). Modern charmcraft
can't pack on these systems, because it requires a newer version of pip
than is available for the system Python. We don't really support these
any more either - at least not for using current versions of ops.
* Add support for jammy (22.04)
* Add support for noble (24.04) - this required a substantial change
because of the required changes to `charmcraft.yaml`. Instead of having
all the bases specified in a `charmcraft.yaml` that's in version control
(which works fine for the older three), have the test generate a
`charmcraft.yaml` that matches the required style for that base.
* Use pytest.mark.parametrize rather than putting the build and deploy
in a single test - this is nicer from a logging/progress indication
point of view, and generally cleaner for what are essentially subtests.
Since modern charmcraft is building each charm separately (and
especially now that it's using a separate yaml for each, to handle
Noble) there isn't really any functional difference in terms of the
test.
* When deploying, use `base=` rather than the deprecated `series=`

To test, run `tox -e smoke` (you'll need to have `charmcraft`, `bash`,
and a Juju controller available).

.gitignore

@@ -24,4 +24,7 @@ venv
 # Smoke test artifacts
 *.tar.gz
 *.charm
+test/charms/test_smoke/.charmcraft_output_packages.txt
 test/charms/test_smoke/requirements.txt
+test/charms/test_smoke/charmcraft.yaml
+juju-crashdump*.tar.xz

test/charms/test_smoke/src/charm.py

@@ -23,25 +23,22 @@
 """
 
 import logging
-import typing
 
-from ops.charm import CharmBase, EventBase
-from ops.main import main
-from ops.model import ActiveStatus
+import ops
 
 logger = logging.getLogger(__name__)
 
 
-class SmokeCharm(CharmBase):
+class SmokeCharm(ops.CharmBase):
     """Charm the service."""
 
-    def __init__(self, *args: typing.Any):
-        super().__init__(*args)
-        self.framework.observe(self.on.install, self._on_install)
+    def __init__(self, framework: ops.Framework):
+        super().__init__(framework)
+        framework.observe(self.on.install, self._on_install)
 
-    def _on_install(self, event: EventBase):
-        self.unit.status = ActiveStatus()
+    def _on_install(self, event: ops.EventBase):
+        self.unit.status = ops.ActiveStatus()
 
 
 if __name__ == '__main__':
-    main(SmokeCharm)
+    ops.main(SmokeCharm)

test/smoke/test_smoke.py

@@ -16,20 +16,56 @@
 
 import logging
 
+import pytest
 from pytest_operator.plugin import OpsTest
 
 logger = logging.getLogger(__name__)
 
 
-async def test_smoke(ops_test: OpsTest):
-    # Verify that we can deploy charms from supported series.
+CHARMCRAFT2_YAML = """
+type: "charm"
+bases:
+  - build-on:
+    - name: "ubuntu"
+      channel: "{base}"
+    run-on:
+    - name: "ubuntu"
+      channel: "{base}"
+"""
 
-    # Build the charm. (We just build it for focal -- it *should* work to deploy it on
-    # older versions of Juju.)
+CHARMCRAFT3_YAML = """
+type: "charm"
+base: ubuntu@{base}
+platforms:
+  amd64:
+parts:
+    charm:
+        plugin: charm
+        source: .
+"""
+
+
+@pytest.mark.parametrize(
+    'base,charmcraft_version,name',
+    (
+        ('20.04', 2, 'focal'),
+        ('22.04', 2, 'jammy'),
+        ('24.04', 3, 'noble'),
+    ),
+)
+async def test_smoke(ops_test: OpsTest, base: str, charmcraft_version: int, name: str):
+    """Verify that we can build and deploy charms from supported bases."""
+    charmcraft_yaml = {
+        2: CHARMCRAFT2_YAML,
+        3: CHARMCRAFT3_YAML,
+    }[charmcraft_version].format(base=base)
+    with open('./test/charms/test_smoke/charmcraft.yaml', 'w') as outf:
+        outf.write(charmcraft_yaml)
     charm = await ops_test.build_charm('./test/charms/test_smoke/')
 
-    for series in ['focal', 'bionic', 'xenial']:
-        app = await ops_test.model.deploy(charm, series=series, application_name=f'{series}-smoke')
-        await ops_test.model.wait_for_idle(timeout=600)
+    app = await ops_test.model.deploy(
+        charm, base=f'ubuntu@{base}', application_name=f'{name}-smoke'
+    )
+    await ops_test.model.wait_for_idle(timeout=600)
 
-        assert app.status == 'active', f"Series {series} failed with '{app.status}' status"
+    assert app.status == 'active', f"Base ubuntu@{base} failed with '{app.status}' status"

tox.ini

@@ -98,7 +98,7 @@ commands =
 
 [testenv:smoke]
 description = Run a smoke test against a Juju controller.
-whitelist_externals = juju
+allowlist_externals = juju
                       charmcraft
                       bash
 deps =
@@ -108,7 +108,7 @@ deps =
     pytest-operator~=0.23
 commands =
     # Build a source tarball for ops, and drop it into the root directory of the smoke test charm.
-    bash -c 'rm -vf ./test/charms/test_smoke/*.tar.gz  # Cleanup old builds'
+    bash -c 'rm -vf ./test/charms/test_smoke/*.tar.gz'
     python -m build --sdist --outdir={toxinidir}/test/charms/test_smoke/
     # Inject the tarball into the smoke test charm's requirements.
     bash -c 'echo "./$(ls -1 ./test/charms/test_smoke/ | grep tar.gz)" > ./test/charms/test_smoke/requirements.txt'