Allow parameterization of keys

`{"task-reference": {"foo-<bar>": "baz"}}` can now resolve `<bar>` to the corresponding task id.

src/taskgraph/util/parameterization.py

@@ -20,6 +20,12 @@ def recurse(val):
             if len(val) == 1:
                 for param_key, param_fn in param_fns.items():
                     if set(val.keys()) == {param_key}:
+                        if isinstance(val[param_key], dict):
+                            # handle `{"task-reference": {"<foo>": "bar"}}`
+                            return {
+                                param_fn(key): recurse(v)
+                                for key, v in val[param_key].items()
+                            }
                         return param_fn(val[param_key])
             return {k: recurse(v) for k, v in val.items()}
         else:

test/test_util_parameterization.py

@@ -90,7 +90,7 @@ def test_task_refs_multiple(assert_task_refs):
 
 
 def test_task_refs_embedded(assert_task_refs):
-    "resolve_task_references resolves ebmedded references"
+    "resolve_task_references resolves embedded references"
     assert_task_refs(
         {"embedded": {"task-reference": "stuff before <edge3> stuff after"}},
         {"embedded": "stuff before tid3 stuff after"},
@@ -124,6 +124,14 @@ def test_task_refs_decision(assert_task_refs):
     )
 
 
+def test_task_refs_key(assert_task_refs):
+    "resolve_task_references resolves task references in a dict's keys"
+    assert_task_refs(
+        {"dict": {"task-reference": {"<edge3>": "<ignored>"}}},
+        {"dict": {"tid3": "<ignored>"}},
+    )
+
+
 def test_task_refs_invalid():
     "resolve_task_references raises a KeyError on reference to an invalid task"
     with pytest.raises(KeyError):