chore: tidy for ruff

src/dewret/workflow.py

@@ -169,7 +169,16 @@ def from_result(result: StepReference) -> Workflow:
         workflow.set_output(result)
         return workflow
 
-    def set_output(self, output: "StepReference") -> None:
+    def set_output(self, output: StepReference) -> None:
+        """Choose the output step.
+
+        Sets a step as being the output for the entire workflow.
+
+        Argument:
+            output: reference to the chosen step.
+        """
+        if output.step.__workflow__ != self:
+            raise RuntimeError("Output must be from a step in this workflow.")
         self.output = output
 
 

tests/test_cwl.py

@@ -1,3 +1,5 @@
+"""Verify CWL output is OK."""
+
 import yaml
 from dewret.tasks import task, run
 from dewret.renderers.cwl import render
@@ -11,6 +13,8 @@ def increment(num: int) -> int:
 
 def test_cwl() -> None:
     """Check whether we can produce simple CWL.
+
+    Produces simplest possible CWL from a workflow.
     """
     result = increment(num=3)
     workflow = run(result)