diff --git a/Lib/test/test_contains.py b/Lib/test/test_contains.py
new file mode 100644
index 0000000..a7ad574
--- /dev/null
+++ b/Lib/test/test_contains.py
@@ -0,0 +1,41 @@
+from test_support import TestFailed
+
+class base_set:
+
+	def __init__(self, el):
+		self.el = el
+
+class set(base_set):
+
+	def __contains__(self, el):
+		return self.el == el
+
+class seq(base_set):
+
+	def __getitem__(self, n):
+		return [self.el][n]
+
+def check(ok, *args):
+    if not ok:
+        raise TestFailed, join(map(str, args), " ")
+
+a = base_set(1)
+b = set(1)
+c = seq(1)
+
+check(1 in b, "1 not in set(1)")
+check(0 not in b, "0 in set(1)")
+check(1 in c, "1 not in seq(1)")
+check(0 not in c, "0 in seq(1)")
+
+try:
+	1 in a
+	check(0, "in base_set did not raise error")
+except AttributeError:
+	pass
+
+try:
+	1 not in a
+	check(0, "not in base_set did not raise error")
+except AttributeError:
+	pass