test: install greenlet on tests workflow

Author: daireto

.github/workflows/tests.yml

@@ -22,6 +22,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
+          pip install greenlet
           pip install coverage
           pip install coveralls
           pip install -r requirements.txt

tests/test_db_connection.py

@@ -19,8 +19,6 @@ async def test_all(self):
         conn = DBConnection(self.DB_URL, echo=False)
 
         logger.info('Testing `init_db` function...')
-        self.assertIsNone(ActiveRecordBaseModel._session)
-        self.assertIsNone(BaseModel._session)
         await conn.init_db()
         await conn.init_db(BaseModel)
         self.assertIsNotNone(ActiveRecordBaseModel._session)