Add explicit tests for writelines

Includes two failing tests that demonstrate a bug where if the data passed to writelines can't be sent in one shot, the remaining buffer isn't written since there is no registered write handler

Lib/test/test_asyncio/test_selector_events.py

@@ -747,6 +747,46 @@ def test_write_sendmsg_no_data(self):
  self.assertFalse(self.sock.sendmsg.called)
  self.assertEqual(list_to_buffer([b'data']), transport._buffer)
 
+ def test_writelines_sendmsg_full(self):
+ data = memoryview(b'data')
+ self.sock.sendmsg = mock.Mock()
+ self.sock.sendmsg.return_value = len(data)
+
+ transport = self.socket_transport(sendmsg=True)
+ transport.writelines([data])
+ self.assertTrue(self.sock.sendmsg.called)
+ self.assertFalse(self.loop.writers)
+
+ def test_writelines_sendmsg_partial(self):
+ data = memoryview(b'data')
+ self.sock.sendmsg = mock.Mock()
+ self.sock.sendmsg.return_value = 2
+
+ transport = self.socket_transport(sendmsg=True)
+ transport.writelines([data])
+ self.assertTrue(self.sock.sendmsg.called)
+ self.assertTrue(self.loop.writers)
+
+ def test_writelines_send_full(self):
+ data = memoryview(b'data')
+ self.sock.send.return_value = len(data)
+ self.sock.send.fileno.return_value = 7
+
+ transport = self.socket_transport(sendmsg=False)
+ transport.writelines([data])
+ self.assertTrue(self.sock.send.called)
+ self.assertFalse(self.loop.writers)
+
+ def test_writelines_send_partial(self):
+ data = memoryview(b'data')
+ self.sock.send.return_value = 2
+ self.sock.send.fileno.return_value = 7
+
+ transport = self.socket_transport(sendmsg=False)
+ transport.writelines([data])
+ self.assertTrue(self.sock.send.called)
+ self.assertTrue(self.loop.writers)
+
  @unittest.skipUnless(selector_events._HAS_SENDMSG, 'no sendmsg')
  def test_write_sendmsg_full(self):
  data = memoryview(b'data')