Update test_json.test_recursion

On FreeBSD 16 with a default stack size of 512 MB, the json C
implementation no longer raises RecursionError in
test_highly_nested_objects_encoding().

Reduce max_depth from 5_000 to 2_000 so
test_highly_nested_objects_encoding() of the Python implementation
only takes 1.6 seconds, instead of 12 seconds.

Author: vstinner

Lib/test/test_json/test_recursion.py

@@ -91,22 +91,35 @@ def test_highly_nested_objects_decoding(self):
     @support.skip_emscripten_stack_overflow()
     @support.requires_resource('cpu')
     def test_highly_nested_objects_encoding(self):
-        # See #12051
+        # See issue gh-56260
+
+        # With max_depth=2_000 on Linux, the Python implementation takes around
+        # 2 seconds to raise RecursionError, whereas the C implementation only
+        # takes around 160 ms.
+        max_depth = 2_000
         l, d = [], {}
-        for x in range(500_000):
+        for x in range(max_depth * 10):
             l, d = [l], {'k':d}
-        with self.assertRaises(RecursionError):
-            with support.infinite_recursion(5000):
+
+        # Don't use assertRaises(RecursionError): on FreeBSD 16 with a default
+        # stack size of 512 MiB, the C implementation doesn't raise
+        # RecursionError.
+        try:
+            with support.infinite_recursion(max_depth):
                 self.dumps(l)
-        with self.assertRaises(RecursionError):
-            with support.infinite_recursion(5000):
+        except RecursionError:
+            pass
+        try:
+            with support.infinite_recursion(max_depth):
                 self.dumps(d)
+        except RecursionError:
+            pass
 
     @support.skip_if_huge_c_stack()
     @support.skip_emscripten_stack_overflow()
     @support.skip_wasi_stack_overflow()
     def test_endless_recursion(self):
-        # See #12051
+        # See issue gh-56260
         class EndlessJSONEncoder(self.json.JSONEncoder):
             def default(self, o):
                 """If check_circular is False, this will keep adding another list."""