Port weird lambda test.

src/RestrictedPython/tests/security_in_syntax.py

@@ -3,11 +3,6 @@
 # Each function in this module is compiled using compile_restricted().
 
 
-def check_getattr_in_lambda(arg=lambda _getattr=(lambda ob, name: name):
-                                       _getattr):
-    42
-
-
 def except_using_bad_name():
     try:
         foo

tests/test_transformer.py

@@ -988,6 +988,22 @@ def test_transformer__RestrictingNodeTransformer__visit_Lambda__7(compile):
     assert code is None
 
 
+BAD_ARG_IN_LAMBDA = """\
+def check_getattr_in_lambda(arg=lambda _bad=(lambda ob, name: name): _bad2):
+    42
+"""
+
+
+@pytest.mark.parametrize(*compile)
+def test_transformer__RestrictingNodeTransformer__visit_Lambda__8(compile):
+    """It prevents arguments starting with `_` in weird lambdas."""
+    code, errors = compile(BAD_ARG_IN_LAMBDA)[:2]
+    # RestrictedPython.compile.compile_restricted_exec finds both invalid
+    # names, while the old implementation seems to abort after the first.
+    assert lambda_err_msg in errors
+    assert code is None
+
+
 @pytest.mark.skipif(
     IS_PY3,
     reason="tuple parameter unpacking is gone in python 3")