Issue #10572: Moved json tests to Lib/test/json_tests.

Approved by Raymond Hettinger.

Lib/test/json_tests/test_recursion.py

@@ -0,0 +1,67 @@
+from unittest import TestCase
+
+import json
+
+class JSONTestObject:
+    pass
+
+
+class RecursiveJSONEncoder(json.JSONEncoder):
+    recurse = False
+    def default(self, o):
+        if o is JSONTestObject:
+            if self.recurse:
+                return [JSONTestObject]
+            else:
+                return 'JSONTestObject'
+        return json.JSONEncoder.default(o)
+
+
+class TestRecursion(TestCase):
+    def test_listrecursion(self):
+        x = []
+        x.append(x)
+        try:
+            json.dumps(x)
+        except ValueError:
+            pass
+        else:
+            self.fail("didn't raise ValueError on list recursion")
+        x = []
+        y = [x]
+        x.append(y)
+        try:
+            json.dumps(x)
+        except ValueError:
+            pass
+        else:
+            self.fail("didn't raise ValueError on alternating list recursion")
+        y = []
+        x = [y, y]
+        # ensure that the marker is cleared
+        json.dumps(x)
+
+    def test_dictrecursion(self):
+        x = {}
+        x["test"] = x
+        try:
+            json.dumps(x)
+        except ValueError:
+            pass
+        else:
+            self.fail("didn't raise ValueError on dict recursion")
+        x = {}
+        y = {"a": x, "b": x}
+        # ensure that the marker is cleared
+        json.dumps(x)
+
+    def test_defaultrecursion(self):
+        enc = RecursiveJSONEncoder()
+        self.assertEqual(enc.encode(JSONTestObject), '"JSONTestObject"')
+        enc.recurse = True
+        try:
+            enc.encode(JSONTestObject)
+        except ValueError:
+            pass
+        else:
+            self.fail("didn't raise ValueError on default recursion")