Moved make_hashable() to django.utils and added tests.

django/db/models/expressions.py

@@ -9,6 +9,7 @@ from django.db.models import fields
 from django.db.models.query_utils import Q
 from django.utils.deconstruct import deconstructible
 from django.utils.functional import cached_property
+from django.utils.hashable import make_hashable
 
 
 class SQLiteNumericMixin:
@@ -138,16 +139,6 @@ class Combinable:
         )
 
 
-def make_hashable(value):
-    if isinstance(value, list):
-        return tuple(map(make_hashable, value))
-    if isinstance(value, dict):
-        return tuple([
-            (key, make_hashable(nested_value)) for key, nested_value in value.items()
-        ])
-    return value
-
-
 @deconstructible
 class BaseExpression:
     """Base class for all query expressions."""

django/utils/hashable.py

@@ -0,0 +1,9 @@
+def make_hashable(value):
+    if isinstance(value, list):
+        return tuple(map(make_hashable, value))
+    if isinstance(value, dict):
+        return tuple([
+            (key, make_hashable(nested_value))
+            for key, nested_value in value.items()
+        ])
+    return value

tests/utils_tests/test_hashable.py

@@ -0,0 +1,25 @@
+from django.test import SimpleTestCase
+from django.utils.hashable import make_hashable
+
+
+class TestHashable(SimpleTestCase):
+    def test_equal(self):
+        tests = (
+            ([], ()),
+            (['a', 1], ('a', 1)),
+            ({}, ()),
+            ({'a'}, {'a'}),
+            (frozenset({'a'}), {'a'}),
+            ({'a': 1}, (('a', 1),)),
+        )
+        for value, expected in tests:
+            with self.subTest(value=value):
+                self.assertEqual(make_hashable(value), expected)
+
+    def test_count_equal(self):
+        tests = (
+            ({'a': 1, 'b': ['a', 1]}, (('a', 1), ('b', ('a', 1)))),
+        )
+        for value, expected in tests:
+            with self.subTest(value=value):
+                self.assertCountEqual(make_hashable(value), expected)