More reliable datasets to recipe conversion (#2472)

Co-authored-by: Valeriu Predoi <valeriu.predoi@gmail.com>

esmvalcore/_recipe/from_datasets.py

@@ -5,9 +5,10 @@
 import itertools
 import logging
 import re
+from collections.abc import Iterable, Mapping, Sequence
 from functools import partial
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Dict, Iterable, Mapping, Sequence
+from typing import TYPE_CHECKING, Any, Dict
 
 from nested_lookup import nested_delete
 
@@ -102,11 +103,13 @@ def _move_datasets_up(recipe: Recipe) -> Recipe:
 
 
 def _to_frozen(item):
-    """Return a frozen and sorted copy of nested dicts and lists."""
-    if isinstance(item, list):
-        return tuple(sorted(_to_frozen(elem) for elem in item))
-    if isinstance(item, dict):
-        return tuple(sorted((k, _to_frozen(v)) for k, v in item.items()))
+    """Return a frozen copy of nested dicts and lists."""
+    if isinstance(item, str):
+        return item
+    if isinstance(item, Mapping):
+        return frozenset((k, _to_frozen(v)) for k, v in item.items())
+    if isinstance(item, Iterable):
+        return frozenset(_to_frozen(elem) for elem in item)
     return item
 
 

tests/unit/recipe/test_from_datasets.py

@@ -23,24 +23,35 @@ def test_to_frozen():
                 "d",
                 "c",
             ],
+            "bb": "dc",
         },
     }
 
     result = _to_frozen(data)
-    expected = (
-        (
-            "a",
+    expected = frozenset(
+        {
             (
-                (
-                    "b",
-                    (
-                        "c",
-                        "d",
-                    ),
+                "a",
+                frozenset(
+                    {
+                        (
+                            "b",
+                            frozenset(
+                                {
+                                    "c",
+                                    "d",
+                                }
+                            ),
+                        ),
+                        (
+                            "bb",
+                            "dc",
+                        ),
+                    }
                 ),
             ),
-        ),
-        ("abc", "x"),
+            ("abc", "x"),
+        }
     )
 
     assert result == expected