Require filter parameters for running tempest test

This helps avoid the case where a user runs a bare
`juju run tempest/0 validation`,
not realising it will run all the tests and take a long time.

Change-Id: I42b67bb941afcc4ed6d9cb905879d81336bfe83f

charms/tempest-k8s/src/charm.py

@@ -247,7 +247,7 @@ class TempestOperatorCharm(sunbeam_charm.OSBaseOperatorCharmK8S):
     def _on_validate_action(self, event: ops.charm.ActionEvent) -> None:
         """Run tempest action."""
         serial: bool = event.params["serial"]
-        regexes: List[str] = event.params["regex"].strip().split()
+        regexes: List[str] = event.params["regex"].split()
         exclude_regex: str = event.params["exclude-regex"].strip()
         test_list: str = event.params["test-list"].strip()
 

charms/tempest-k8s/src/handlers.py

@@ -198,6 +198,15 @@ class TempestPebbleHandler(sunbeam_chandlers.ServicePebbleHandler):
         Raises a RuntimeError if something goes wrong.
         """
         # validation before running anything
+
+        if not (regexes or exclude_regex or test_list):
+            raise RuntimeError(
+                "No filter parameters provided.\n"
+                "At least one of regex, exclude-regex, or test-list must be provided to run tests.\n\n"
+                "If you really intend to run all tests, pass regex='.*'.\n"
+                "WARNING: the full test set is very large and will take a long time."
+            )
+
         for r in [*regexes, exclude_regex]:
             try:
                 re.compile(r)

charms/tempest-k8s/tests/unit/test_tempest_charm.py

@@ -299,14 +299,14 @@ class TestTempestOperatorCharm(test_utils.CharmTestCase):
         action_event = mock.Mock()
         action_event.params = {
             "serial": False,
-            "regex": "",
+            "regex": "smoke",
             "exclude-regex": "",
             "test-list": "",
         }
         self.harness.charm._on_validate_action(action_event)
         action_event.fail.assert_not_called()
         exec_mock.assert_called_with(
-            ["tempest-run-wrapper", "--parallel"],
+            ["tempest-run-wrapper", "--parallel", "--regex", "smoke"],
             user="tempest",
             group="tempest",
             working_dir=TEMPEST_HOME,
@@ -368,6 +368,31 @@ class TestTempestOperatorCharm(test_utils.CharmTestCase):
         self.harness.remove_relation(identity_ops_rel_id)
         self.harness.remove_relation(grafana_dashboard_rel_id)
 
+    def test_validate_action_no_params(self):
+        """Test validate action with no filter params."""
+        test_utils.set_all_pebbles_ready(self.harness)
+        self.add_logging_relation(self.harness)
+        self.add_identity_ops_relation(self.harness)
+        self.add_grafana_dashboard_relation(self.harness)
+
+        exec_mock = mock.Mock()
+        self.harness.charm.pebble_handler().execute = exec_mock
+
+        action_event = mock.Mock()
+        action_event.params = {
+            "serial": True,
+            "regex": "",
+            "exclude-regex": "",
+            "test-list": "",
+        }
+        self.harness.charm._on_validate_action(action_event)
+        action_event.fail.assert_called_once()
+        self.assertIn(
+            "No filter parameters provided",
+            action_event.fail.call_args.args[0],
+        )
+        exec_mock.assert_not_called()
+
     def test_get_list_action(self):
         """Test get-list action."""
         test_utils.set_all_pebbles_ready(self.harness)