Add tests for __init__() and update() with no args.
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index 80ee2c5..13ae9bf 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -396,8 +396,10 @@
self.assertRaises(TypeError, hash, c)
c.update(dict(a=5, b=3, c=1))
c.update(Counter('a' * 50 + 'b' * 30))
+ c.update() # test case with no args
c.__init__('a' * 500 + 'b' * 300)
c.__init__('cdc')
+ c.__init__()
self.assertEqual(c, dict(a=555, b=333, c=3, d=1))
self.assertEqual(c.setdefault('d', 5), 1)
self.assertEqual(c['d'], 1)