Use async_generator package to avoid syntax error on python<3.6

Author: mehaase

requirements.txt

@@ -5,3 +5,4 @@ pytest==4.3.1
 six==1.12.0
 trio==0.11.0
 pytest-trio==0.5.2
+async-generator==1.10

tests/integration/test_trio.py

@@ -1,31 +1,36 @@
+from collections import namedtuple
 import os
 import sys
-from collections import namedtuple
+
+from async_generator import async_generator, yield_
 import pytest
 from rethinkdb import RethinkDB
 from rethinkdb.errors import ReqlRuntimeError
 import trio
 
+
 INTEGRATION_TEST_DB = 'integration_test'
 r = RethinkDB()
 r.set_loop_type('trio')
 
 
 @pytest.fixture
+@async_generator
 async def integration_db(nursery):
     async with r.open(db='test', nursery=nursery) as conn:
         try:
             await r.db_create(INTEGRATION_TEST_DB).run(conn)
         except ReqlRuntimeError:
             pass
-    yield r.db(INTEGRATION_TEST_DB)
+    await yield_(r.db(INTEGRATION_TEST_DB))
 
 
 @pytest.fixture
+@async_generator
 async def marvel_table(integration_db, nursery):
     async with r.open(db='test', nursery=nursery) as conn:
         await r.table_create('marvel').run(conn)
-        yield r.table('marvel')
+        await yield_(r.table('marvel'))
         await r.table_drop('marvel').run(conn)