Implement initial structure and core functionality for Duck Preview application

tests/test_collector.py

@@ -0,0 +1,22 @@
+import time
+from unittest.mock import MagicMock
+
+from duck_preview.telemetry.collector import TelemetryCollector
+
+
+def test_metrics_empty():
+    collector = TelemetryCollector()
+    metrics = collector.metrics()
+    assert metrics == {"fps": 0, "frame_time_ms": 0.0, "frame_count": 0}
+
+
+def test_metrics_after_frames():
+    collector = TelemetryCollector()
+    mock = MagicMock()
+    for _ in range(30):
+        collector.on_frame(mock)
+        time.sleep(0.002)
+
+    metrics = collector.metrics()
+    assert metrics["frame_count"] >= 30
+    assert metrics["frame_time_ms"] > 0

tests/test_dispatcher.py

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+from duck_preview.dispatcher.frame_dispatcher import FrameDispatcher
+
+
+def test_subscribe_notified():
+    dispatcher = FrameDispatcher()
+    received = []
+
+    def cb(frame):
+        received.append(frame)
+
+    dispatcher.subscribe(cb)
+    dispatcher.on_frame("test")
+
+    assert received == ["test"]
+
+
+def test_unsubscribe_not_notified():
+    dispatcher = FrameDispatcher()
+    received = []
+
+    def cb(frame):
+        received.append(frame)
+
+    dispatcher.subscribe(cb)
+    dispatcher.unsubscribe(cb)
+    dispatcher.on_frame("test")
+
+    assert received == []
+
+
+def test_multiple_subscribers():
+    dispatcher = FrameDispatcher()
+    received_1 = []
+    received_2 = []
+
+    def cb1(frame):
+        received_1.append(frame)
+
+    def cb2(frame):
+        received_2.append(frame)
+
+    dispatcher.subscribe(cb1)
+    dispatcher.subscribe(cb2)
+    dispatcher.on_frame("test")
+
+    assert received_1 == ["test"]
+    assert received_2 == ["test"]