Response to review

Author: wxtim

cylc/flow/config.py

@@ -2270,7 +2270,7 @@ def load_graph(self):
 
             # Checking for undefined outputs for terminal tasks. Tasks with
             # dependencies are checked in generate_triggers:
-            self.check_outputs(parser.terminals)
+            self.check_terminal_outputs(parser.terminals)
 
         self.set_required_outputs(task_output_opt)
 
@@ -2284,12 +2284,16 @@ def load_graph(self):
         for tdef in self.taskdefs.values():
             tdef.tweak_outputs()
 
-    def check_outputs(self, terminals: Iterable[str]) -> None:
+    def check_terminal_outputs(self, terminals: Iterable[str]) -> None:
         """Check that task outputs have been registered with tasks.
 
+
+        Where a "terminal output" is an output for a task at the end of a
+        graph string, such as "end" in `start => middle => end`.
+
         Raises: WorkflowConfigError if a custom output is not defined.
         """
-        # TODO (On drop 3.7): Can be simplified with walrus :=
+        # BACK COMPAT: (On drop 3.7): Can be simplified with walrus :=
         # if (b := a[1].strip("?")) not in TASK_QUALIFIERS
         terminal_outputs = [
             (a[0].strip("!"), a[1].strip("?"))

cylc/flow/task_outputs.py

@@ -601,7 +601,7 @@ def color_wrap(string, is_complete):
     @staticmethod
     def is_valid_std_name(name: str) -> bool:
         """Check name is a valid standard output name."""
-        return name in TASK_OUTPUTS
+        return name in SORT_ORDERS
 
     @staticmethod
     def output_sort_key(item: Iterable[str]) -> float:

tests/unit/test_config.py

@@ -1743,7 +1743,9 @@ def test_check_outputs(tmp_path, registered_outputs, tasks_and_outputs, fails):
     cfg = WorkflowConfig('', tmp_path / 'flow.cylc', '')
     cfg.cfg['runtime']['foo']['outputs'] = registered_outputs
     if fails:
-        with pytest.raises(WorkflowConfigError, match='Undefined custom output'):
-            cfg.check_outputs(tasks_and_outputs)
+        with pytest.raises(
+            WorkflowConfigError, match='Undefined custom output'
+        ):
+            cfg.check_terminal_outputs(tasks_and_outputs)
     else:
-        assert cfg.check_outputs(tasks_and_outputs) is None
+        assert cfg.check_terminal_outputs(tasks_and_outputs) is None