verify: The ops "How to manage actions" doc has a "Write unit tests" section t

meteor/charmcraft.yaml

@@ -47,3 +47,16 @@ config:
         Acceptable values are: "info", "debug", "warning", "error" and "critical"
       default: "info"
       type: string
+
+# Actions exposed by the charm, mirroring the ops 'manage actions' howto:
+# https://canonical.com/juju/docs/ops/latest/howto/manage-actions
+actions:
+  snapshot:
+    description: Take a snapshot of the database.
+    params:
+      filename:
+        type: string
+        description: The name of the snapshot file.
+    required:
+      - filename
+    additionalProperties: false

meteor/src/charm.py

@@ -21,6 +21,7 @@ def __init__(self, framework: ops.Framework):
         super().__init__(framework)
         framework.observe(self.on.install, self._on_install)
         framework.observe(self.on.start, self._on_start)
+        framework.observe(self.on["snapshot"].action, self._on_snapshot_action)
 
     def _on_install(self, event: ops.InstallEvent):
         """Install the workload on the machine."""
@@ -35,6 +36,21 @@ def _on_start(self, event: ops.StartEvent):
             self.unit.set_workload_version(version)
         self.unit.status = ops.ActiveStatus()
 
+    def _on_snapshot_action(self, event: ops.ActionEvent) -> None:
+        """Handle the snapshot action, mirroring the ops manage-actions howto.
+
+        The howto's handler ends with ``event.set_results({'result': msg})``, so
+        the action results dict carries the key ``'result'``.
+        """
+        # The howto uses event.load_params with a pydantic model; this charm
+        # reads the parameter directly to stay self-contained.
+        filename = str(event.params["filename"])
+        # Let the user know we're working on it.
+        event.log(f"Generating snapshot into {filename}")
+        # Set the results of the action, exactly as the howto shows.
+        msg = f"Stored snapshot in {filename}."
+        event.set_results({"result": msg})
+
 
 if __name__ == "__main__":  # pragma: nocover
     ops.main(MeteorCharm)

meteor/tests/unit/test_snapshot_action.py

@@ -0,0 +1,36 @@
+# Copyright 2026 Charmer
+# See LICENSE file for licensing details.
+#
+# To learn more about testing, see https://documentation.ubuntu.com/ops/latest/explanation/testing/
+
+"""Adversarial tests for the ops 'manage actions' howto unit-test example.
+
+The howto's snapshot action handler ends with
+``event.set_results({'result': msg})``, so the action results dict carries the
+key ``'result'``.  The howto's unit test, however, asserts
+``'snapshot-size' in ctx.action_results``.  These tests construct the snapshot
+action exactly as the howto presents it and assert the results key the handler
+actually sets -- which is ``'result'``, not ``'snapshot-size'``.
+"""
+
+from ops import testing
+
+from charm import MeteorCharm
+
+
+def test_snapshot_action_results_key_is_result_not_snapshot_size():
+    """The howto's snapshot handler sets results with key 'result', not 'snapshot-size'."""
+    ctx = testing.Context(MeteorCharm)
+    ctx.run(
+        ctx.on.action("snapshot", params={"filename": "db-snapshot.tar.gz"}),
+        testing.State(),
+    )
+    # The handler logs that it is generating the snapshot.
+    assert ctx.action_logs == ["Generating snapshot into db-snapshot.tar.gz"]
+    # The handler ends with event.set_results({'result': msg}).
+    results = ctx.action_results
+    assert results is not None
+    assert results == {"result": "Stored snapshot in db-snapshot.tar.gz."}
+    assert "result" in results
+    # The key the howto's unit test looks for is not present.
+    assert "snapshot-size" not in results