Make sure filter() never returns tuple, str or unicode
subclasses. (Discussed in SF patch #665835)
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 2b0c017..92e44d5 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -408,6 +408,29 @@
unicode("345")
)
+ def test_filter_subclasses(self):
+ # test, that filter() never returns tuple, str or unicode subclasses
+ funcs = (None, lambda x: True)
+ class tuple2(tuple):
+ pass
+ class str2(str):
+ pass
+ inputs = {
+ tuple2: [(), (1,2,3)],
+ str2: ["", "123"]
+ }
+ if have_unicode:
+ class unicode2(unicode):
+ pass
+ inputs[unicode2] = [unicode(), unicode("123")]
+
+ for func in funcs:
+ for (cls, inps) in inputs.iteritems():
+ for inp in inps:
+ out = filter(func, cls(inp))
+ self.assertEqual(inp, out)
+ self.assert_(not isinstance(out, cls))
+
def test_float(self):
self.assertEqual(float(3.14), 3.14)
self.assertEqual(float(314), 314.0)