Make the workflow iterable

opentech/apply/tests.py

@@ -16,6 +16,13 @@ class TestWorkflowCreation(SimpleTestCase):
         with self.assertRaises(ValueError):
             Workflow(name)
 
+    def test_can_iterate_through_workflow(self):
+        stage1 = Stage('stage_one')
+        stage2 = Stage('stage_two')
+        workflow = Workflow('two_stage', stage1, stage2)
+        for stage, check in zip(workflow, [stage1, stage2]):
+            self.assertEqual(stage, check)
+
 
 class TestStageCreation(SimpleTestCase):
     def test_can_create_stage(self):

opentech/apply/workflow.py

-class Workflow:
-    def __init__(self, name: str, *stages: Stage) -> None:
+from typing import Iterator, Iterable
+
+
+class Workflow(Iterable['Stage']):
+    def __init__(self, name: str, *stages: 'Stage') -> None:
         self.name = name
         if not stages:
             raise ValueError('Stages must be supplied')
         self.stages = stages
 
+    def __iter__(self) -> Iterator['Stage']:
+        yield from self.stages
+
 
 class Stage:
     def __init__(self, name: str) -> None: