feat: implement slot_error_boundary decorator and add unit tests for session and device controllers

tests/test_session_controller.py

@@ -0,0 +1,48 @@
+import pytest
+from unittest.mock import MagicMock, patch
+from pygui.backend.controllers.session_controller import SessionController
+
+@pytest.fixture
+def controller():
+    return SessionController()
+
+def test_initial_default(controller):
+    assert controller.mode == "review"
+    assert controller.state == "idle"
+    assert controller.recording == False
+
+def test_playback_flow(controller):
+    controller.loadFile("tests/fixtures/sample_stream.csv")
+    controller.play()
+    initial_index = controller.frameIndex
+    controller._advance()
+    assert controller.frameIndex == initial_index + 1
+
+def test_speed_control(controller):
+    controller.setSpeed(2.0)
+    interval = controller._next_interval_ms()
+    controller.setSpeed(0.5)
+    assert controller._next_interval_ms() > interval
+
+def test_seek(controller):
+    controller.loadFile("tests/fixtures/sample_stream.csv")
+    controller.seek(1)
+    assert controller.frameIndex == 1
+
+def test_step_forward(controller):
+    controller.loadFile("tests/fixtures/sample_stream.csv")
+    initial = controller.frameIndex
+    controller.step(1)
+    assert controller.frameIndex == initial + 1
+
+def test_step_backward(controller):
+    controller.loadFile("tests/fixtures/sample_stream.csv")
+    controller.seek(2)
+    controller.step(-1)
+    assert controller.frameIndex == 1
+
+def test_pause_stop_timer(controller):
+    controller.loadFile("tests/fixtures/sample_stream.csv")
+    controller.seek(2)
+    controller.stop()
+    assert controller.frameIndex == 0