import unittest
import time
import multiprocessing as mp


class TestPoll(unittest.TestCase):

    def test_empty_string(self):
        a, b = mp.Pipe()
        self.assertEqual(a.poll(), False)
        b.send_bytes(b'')
        self.assertEqual(a.poll(), True)
        self.assertEqual(a.poll(), True)

    @classmethod
    def _child_strings(cls, conn, strings):
        for s in strings:
            time.sleep(0.1)
            conn.send_bytes(s)
        conn.close()

    def test_strings(self):
        strings = (b'hello', b'', b'a', b'b', b'', b'bye', b'', b'lop')
        a, b = mp.Pipe()
        p = mp.Process(target=self._child_strings, args=(b, strings))
        p.start()

        for s in strings:
            for i in range(200):
                if a.poll(0.01):
                    break
            self.assertEqual(s, a.recv_bytes())

        p.join()

    @classmethod
    def _child_dont_merge(cls, b):
        b.send_bytes(b'a')
        b.send_bytes(b'b')
        b.send_bytes(b'cd')

    def test_dont_merge(self):
        a, b = mp.Pipe()
        self.assertEqual(a.poll(0.0), False)
        self.assertEqual(a.poll(0.1), False)

        p = mp.Process(target=self._child_dont_merge, args=(b,))
        p.start()

        self.assertEqual(a.recv_bytes(), b'a')
        self.assertEqual(a.poll(1.0), True)
        self.assertEqual(a.poll(1.0), True)
        self.assertEqual(a.recv_bytes(), b'b')
        self.assertEqual(a.poll(1.0), True)
        self.assertEqual(a.poll(1.0), True)
        self.assertEqual(a.poll(0.0), True)
        self.assertEqual(a.recv_bytes(), b'cd')

        p.join()


if __name__ == '__main__':
    unittest.main()