=================================== FAILURES ===================================
______________________ TestConnection.test_wantWriteError ______________________

self = <tests.test_ssl.TestConnection object at 0x7fffe9eabd10>

    def test_wantWriteError(self):
        """
            `Connection` methods which generate output raise
            `OpenSSL.SSL.WantWriteError` if writing to the connection's BIO
            fail indicating a should-write state.
            """
        client_socket, server_socket = socket_pair()
        # Fill up the client's send buffer so Connection won't be able to write
        # anything.  Only write a single byte at a time so we can be sure we
        # completely fill the buffer.  Even though the socket API is allowed to
        # signal a short write via its return value it seems this doesn't
        # always happen on all platforms (FreeBSD and OS X particular) for the
        # very last bit of available buffer space.
        msg = b"x"
        for i in range(1024 * 1024 * 4):
            try:
                client_socket.send(msg)
            except error as e:
                if e.errno == EWOULDBLOCK:
                    break
                raise
        else:
            pytest.fail(
>               "Failed to fill socket buffer, cannot test BIO want write")
E           Failed: Failed to fill socket buffer, cannot test BIO want write

tests/test_ssl.py:2593: Failed
===================== 1 failed, 490 passed in 7.54 seconds =====================