Add a unittest for the exact JSON format

Author: matthiask

tests/testapp/test_data.py

@@ -1,5 +1,7 @@
 import json
+from unittest import skipIf
 
+import django
 from django.db import models
 from django.test import TransactionTestCase
 
@@ -644,3 +646,19 @@ def test_mti(self):
                 {"model": "testapp.uniqueslugmti", "pk": t2.pk, "fields": {}},
             ],
         )
+
+    @skipIf(
+        django.VERSION > (6,),
+        "Django changed the JSON dump format to include a final newline.",
+    )
+    def test_json_format(self):
+        """The exact format generated by dump_specs shouldn't change without us noticing"""
+
+        Tag.objects.create(name="Hello")
+        specs = [*specs_for_models([Tag])]
+        data = dump_specs(specs)
+
+        self.assertEqual(
+            data,
+            '{"version": 1, "specs": [{"model": "testapp.tag"}], "objects": [{"model": "testapp.tag", "pk": 5, "fields": {"name": "Hello", "parent": null}}]}',
+        )