Merge pull request #64 from canonical/fix-no-remote-unit-ids-evt

fix error when no remote unit data is passed to relation

pyproject.toml

@@ -8,7 +8,7 @@ build-backend = "setuptools.build_meta"
 [project]
 name = "ops-scenario"
 
-version = "5.3"
+version = "5.3.1"
 
 authors = [
  { name = "Pietro Pasotti", email = "[email protected]" }

scenario/runtime.py

@@ -231,13 +231,18 @@ def _get_event_env(self, state: "State", event: "Event", charm_root: Path):
  "but you probably should be parametrizing the event with `remote_unit_id` "
  "to be explicit.",
  )
- else:
+ elif len(remote_unit_ids) > 1:
  remote_unit_id = remote_unit_ids[0]
  logger.warning(
  "remote unit ID unset, and multiple remote unit IDs are present; "
  "We will pick the first one and hope for the best. You should be passing "
  "`remote_unit_id` to the Event constructor.",
  )
+ else:
+ logger.warning(
+ "remote unit ID unset; no remote unit data present. "
+ "Is this a realistic scenario?", # TODO: is it?
+ )
 
  if remote_unit_id is not None:
  remote_unit = f"{remote_app_name}/{remote_unit_id}"

scenario/state.py

@@ -193,7 +193,7 @@ def _update_metadata(
 
 
 def normalize_name(s: str):
- """Event names need underscores instead of dashes."""
+ """Event names, in Scenario, uniformly use underscores instead of dashes."""
  return s.replace("-", "_")
 
 
@@ -927,9 +927,6 @@ def __call__(self, remote_unit_id: Optional[int] = None) -> "Event":
  return self.replace(relation_remote_unit_id=remote_unit_id)
 
  def __post_init__(self):
- if "-" in self.path:
- logger.warning(f"Only use underscores in event paths. {self.path!r}")
-
  path = normalize_name(self.path)
  # bypass frozen dataclass
  object.__setattr__(self, "path", path)

tests/test_e2e/test_relations.py

@@ -223,6 +223,42 @@ def callback(charm: CharmBase, event):
  )
 
 
+@pytest.mark.parametrize(
+ "evt_name",
+ ("changed", "broken", "departed", "joined", "created"),
+)
+def test_relation_events_no_remote_units(mycharm, evt_name, caplog):
+ relation = Relation(
+ endpoint="foo",
+ interface="foo",
+ remote_units_data={}, # no units
+ )
+
+ def callback(charm: CharmBase, event):
+ assert event.app # that's always present
+ assert not event.unit
+
+ mycharm._call = callback
+
+ trigger(
+ State(
+ relations=[
+ relation,
+ ],
+ ),
+ getattr(relation, f"{evt_name}_event"),
+ mycharm,
+ meta={
+ "name": "local",
+ "requires": {
+ "foo": {"interface": "foo"},
+ },
+ },
+ )
+
+ assert "remote unit ID unset; no remote unit data present" in caplog.text
+
+
 @pytest.mark.parametrize("data", (set(), {}, [], (), 1, 1.0, None, b""))
 def test_relation_unit_data_bad_types(mycharm, data):
  with pytest.raises(StateValidationError):