Refactor code structure for improved readability and maintainability

tests/test_stream_reader.py

@@ -0,0 +1,28 @@
+import time 
+from pygui.backend.frame import Frame
+from pygui.serialcomm.stream_reader import StreamReader
+
+class FakeTransport:
+    """Yield canned line then blocks (returns b'')."""
+    def __init__(self, lines): self._lines = list(lines); self.closed = False
+    def readline(self):
+        time.sleep(0.001)
+        return self._lines.pop(0) if self._lines else b""
+    def close(self): self.closed = True
+    
+def parse_line(raw: str, seq: int) -> Frame:
+    parts = [float(x) for x in raw.split(",")]
+    return Frame(seq = seq, time = parts[0], values = parts[1:])
+
+def test_reads_frames_and_counts_errors():
+    got, errors = [], []
+    transport = FakeTransport([b"0.0,149,148\n", b"garbage\n", b"0.5,150,149\n"])
+    r = StreamReader(transport, parse_line,
+                    on_frame = got.append, on_error = lambda e: errors.append(e))
+    
+    r.start()
+    time.sleep(0.1)
+    r.stop()
+    assert [f.values for f in got] == [[149.0, 148.0], [150.0, 149.0]]
+    assert r.error_count == 1
+    assert transport.closed