Method writer

tests/test_copy.py:236–240

(data)

    async def test_copy_from_query_to_sink(self):
        with tempfile.NamedTemporaryFile() as f:
            async def writer(data):
                # Sleeping here to simulate slow output sink to test
                # backpressure.
                await asyncio.sleep(0.05)
                f.write(data)

            await self.con.copy_from_query('''
                SELECT