Check cache hash is up-to-date in unit test

python/test/test_action_yml.py

@@ -1,3 +1,4 @@
+import hashlib
 import pathlib
 import unittest
 
@@ -28,6 +29,15 @@ def test_composite_action(self):
         self.assertEqual(dockerfile_action_wo_runs, composite_action_wo_runs)
         self.assertIn(('using', 'composite'), composite_action.get('runs', {}).items())
 
+        # check cache key hash is up-to-date in composite action
+        with open(project_root / 'python' / 'requirements.txt', mode='rb') as r:
+            expected_hash = hashlib.md5(r.read()).hexdigest()
+        cache_hash = next(step.get('with', {}).get('key', '').split('-')[-1]
+                          for step in composite_action.get('runs', {}).get('steps', [])
+                          if step.get('uses', '').startswith('actions/cache/restore@'))
+        self.assertEqual(expected_hash, cache_hash, msg='Changing python/requirements.txt requires '
+                                                        'to update the MD5 hash in composite/action.yaml')
+
     def test_composite_inputs(self):
         with open(project_root / 'composite/action.yml', encoding='utf-8') as r:
             action = yaml.safe_load(r)