stream: use async I/O to avoid real-time problems.

tests/test_async.py

@@ -0,0 +1,70 @@
+import mock
+import time
+import pytest
+from amodem import async
+import logging
+
+logging.basicConfig(format='%(message)s')
+
+
+def test_async_reader():
+    def _read(n):
+        time.sleep(n * 0.1)
+        return b'\x00' * n
+    s = mock.Mock()
+    s.read = _read
+    r = async.AsyncReader(s, 1)
+
+    n = 5
+    assert r.read(n) == b'\x00' * n
+    r.close()
+    assert r.stream is None
+    r.close()
+
+
+def test_async_write():
+    result = []
+
+    def _write(buf):
+        time.sleep(len(buf) * 0.1)
+        result.append(buf)
+    s = mock.Mock()
+    s.write = _write
+    w = async.AsyncWriter(s)
+
+    w.write('foo')
+    w.write(' ')
+    w.write('bar')
+    w.close()
+    assert w.stream is None
+    w.close()
+    assert result == ['foo', ' ', 'bar']
+
+
+def test_async_reader_error():
+    s = mock.Mock()
+    s.read.side_effect = IOError()
+    r = async.AsyncReader(s, 1)
+    with pytest.raises(IOError):
+        r.read(3)
+
+
+def test_async_writer_error():
+    s = mock.Mock()
+    s.write.side_effect = IOError()
+    w = async.AsyncWriter(s)
+    w.write('123')
+    w.thread.join()
+    with pytest.raises(IOError):
+        w.write('456')
+    assert s.write.mock_calls == [mock.call('123')]
+
+
+def test_underflow():
+    s = mock.Mock()
+    w = async.AsyncWriter(s)
+    w.write('blah')
+    w.thread.join()
+    assert s.write.mock_calls == [mock.call('blah')]
+    with pytest.raises(IOError):
+        w.write('xyzw')