1 files changed, 30 insertions, 0 deletions
diff --git a/Lib/json/tests/test_check_circular.py b/Lib/json/tests/test_check_circular.py
new file mode 100644
index 0000000..3c3f96a
--- /dev/null
+++ b/Lib/json/tests/test_check_circular.py
@@ -0,0 +1,30 @@
+from unittest import TestCase
+import json
+
+def default_iterable(obj):
+    return list(obj)
+
+class TestCheckCircular(TestCase):
+    def test_circular_dict(self):
+        dct = {}
+        dct['a'] = dct
+        self.assertRaises(ValueError, json.dumps, dct)
+
+    def test_circular_list(self):
+        lst = []
+        lst.append(lst)
+        self.assertRaises(ValueError, json.dumps, lst)
+
+    def test_circular_composite(self):
+        dct2 = {}
+        dct2['a'] = []
+        dct2['a'].append(dct2)
+        self.assertRaises(ValueError, json.dumps, dct2)
+
+    def test_circular_default(self):
+        json.dumps([set()], default=default_iterable)
+        self.assertRaises(TypeError, json.dumps, [set()])
+
+    def test_circular_off_default(self):
+        json.dumps([set()], default=default_iterable, check_circular=False)
+        self.assertRaises(TypeError, json.dumps, [set()], check_circular=False)