Example to write test using multiple deferred in the same test.

reuse_threadpool.py

class TestDatabaseHandlerSQLite(ServerTestCase):
    """
    Integration tests for the SQLite database log handler.
    """

    def setUp(self):
        super(TestDatabaseHandlerSQLite, self).setUp()
        self.pool = DBConnectionPool('sqlite://:memory:')
        self.handler = DatabaseHandler(self.pool, capacity=1)
        self.handler._scheduler = Clock()

        # FIXME:XXX:
        # Replace Twistar singleton approach with per instance
        # attributes.
        Registry.DBPOOL = self.pool._pool
        Registry.IMPL = self.pool.getTranslator()

        self.handler.configure()

        # # patch handler and test _insertEntry
        prev = self.handler._insertEntry

        def mockInsertEntry(entry):
            deferred = prev(entry)
            self.getDeferredResult(deferred)
            return deferred

        self.handler._insertEntry = mockInsertEntry

        # Create log database.
        create_deferred = self.pool.runQuery(
            'CREATE TABLE ' + LogEntry.TABLENAME +
            ' (id INTEGER PRIMARY KEY ASC, message VARCHAR(120))'
            )
        self.getDeferredResult(create_deferred, prevent_stop=True)