added test for testing encoded unicode values in meta using msgpack codec

Author: voith

tests/test_codecs.py

@@ -20,7 +20,8 @@ def check_request(req1, req2):
 
     enc = encoder(Request, send_body=True)
     dec = decoder(Request, Response)
-    req = Request(url="http://www.yandex.ru",method=b'GET', meta={b"test": b"shmest"}, headers={b'reqhdr': b'value'})
+    req = Request(url="http://www.yandex.ru", method=b'GET',
+                  meta={b'test': b'shmest', b'scrapy_meta': {'rule': 0, 'key': 'value'}}, headers={b'reqhdr': b'value'})
     req2 = Request(url="http://www.yandex.ru/search")
     msgs = [
         enc.encode_add_seeds([req]),