Style fixes

reframe/utility/typecheck.py

@@ -325,9 +325,9 @@ def __rfm_cast_str__(cls, s):
         value_type = cls._value_type
 
         try:
-            d = json.loads(s)
+            items = json.loads(s)
         except json.JSONDecodeError:
-            seq = []
+            items = []
             for key_datum in s.split(','):
                 try:
                     k, v = key_datum.split(':')
@@ -337,11 +337,9 @@ def __rfm_cast_str__(cls, s):
                         f'cannot convert string {s!r} to {cls.__name__!r}'
                     ) from None
 
-                seq.append((key_type(k), value_type(v)))
+                items.append((key_type(k), value_type(v)))
 
-            return mappping_type(seq)
-        else:
-            return mappping_type(d)
+        return mappping_type(items)
 
 
 class _StrType(_SequenceType):

unittests/test_typecheck.py

@@ -209,12 +209,12 @@ def test_mapping_type():
     assert typ.Dict[str, int]('a:1,b:2') == {'a': 1, 'b': 2}
 
     # Conversion with JSON syntax, for nested dictionaries
-    s = '{"gpu":{"num_gpus_per_node":8}, "mpi": {"num_slots": 64}}'
-    assert (typ.Dict[str, typ.Dict[str, object]](s) ==
-            {
-                "gpu": {"num_gpus_per_node": 8},
-                "mpi": {"num_slots": 64},
-            })
+    s = '{"gpu":{"num_gpus_per_node": 8}, "mpi": {"num_slots": 64}}'
+    expected = {
+        'gpu': {'num_gpus_per_node': 8},
+        'mpi': {'num_slots': 64},
+    }
+    assert typ.Dict[str, typ.Dict[str, object]](s) == expected
 
     with pytest.raises(TypeError):
         typ.Dict[str, int]('a:1,b')