fix: improve JSON-safe rendering for sets

tests/test_util.py

@@ -735,6 +735,30 @@ class TestMakeJsonSafe(TestCase):
             ],
         )
 
+    def test_set(self):
+        model = self.app.model
+        person = model.Person(full_name="Betty Boop")
+
+        data = {
+            "foo",
+            "bar",
+            person,
+        }
+
+        self.assertRaises(TypeError, json.dumps, data)
+        value = mod.make_json_safe(data)
+        self.assertNotIsInstance(value, set)
+        self.assertIsInstance(value, list)
+        # nb. must sort values, otherwise comparison may fail
+        self.assertEqual(
+            sorted(value),
+            [
+                "Betty Boop",  # nb. upper-case sorts first
+                "bar",
+                "foo",
+            ],
+        )
+
 
 class TestRenderVueFinalize(TestCase):