bpo-26806: add 30 to the recursion limit in IDLE's shell (GH-13944)

This is done to compensate for the extra stack frames added by
IDLE itself, which cause problems when setting the recursion limit
to low values.

This wraps sys.setrecursionlimit() and sys.getrecursionlimit()
as invisibly as possible.

1 files changed, 33 insertions, 0 deletions

diff --git a/Lib/idlelib/idle_test/test_run.py b/Lib/idlelib/idle_test/test_run.py
index 46f0235..d0f1e92 100644
--- a/Lib/idlelib/idle_test/test_run.py
+++ b/Lib/idlelib/idle_test/test_run.py
@@ -6,6 +6,8 @@ from unittest import mock
 from test.support import captured_stderr
 
 import io
+import sys
+
 
 class RunTest(unittest.TestCase):
 
@@ -260,5 +262,36 @@ class PseudeOutputFilesTest(unittest.TestCase):
         self.assertRaises(TypeError, f.close, 1)
 
 
+class TestSysRecursionLimitWrappers(unittest.TestCase):
+
+    def test_bad_setrecursionlimit_calls(self):
+        run.install_recursionlimit_wrappers()
+        self.addCleanup(run.uninstall_recursionlimit_wrappers)
+        f = sys.setrecursionlimit
+        self.assertRaises(TypeError, f, limit=100)
+        self.assertRaises(TypeError, f, 100, 1000)
+        self.assertRaises(ValueError, f, 0)
+
+    def test_roundtrip(self):
+        run.install_recursionlimit_wrappers()
+        self.addCleanup(run.uninstall_recursionlimit_wrappers)
+
+        # check that setting the recursion limit works
+        orig_reclimit = sys.getrecursionlimit()
+        self.addCleanup(sys.setrecursionlimit, orig_reclimit)
+        sys.setrecursionlimit(orig_reclimit + 3)
+
+        # check that the new limit is returned by sys.getrecursionlimit()
+        new_reclimit = sys.getrecursionlimit()
+        self.assertEqual(new_reclimit, orig_reclimit + 3)
+
+    def test_default_recursion_limit_preserved(self):
+        orig_reclimit = sys.getrecursionlimit()
+        run.install_recursionlimit_wrappers()
+        self.addCleanup(run.uninstall_recursionlimit_wrappers)
+        new_reclimit = sys.getrecursionlimit()
+        self.assertEqual(new_reclimit, orig_reclimit)
+
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)