Add IMU frame loss analysis script

tests/test_analyze_imu_frame_loss.py

@@ -0,0 +1,58 @@
+import tempfile
+import unittest
+from pathlib import Path
+
+from scripts import analyze_imu_frame_loss
+
+
+class AnalyzeImuFrameLossTests(unittest.TestCase):
+    def _write_csv(self, path: Path, times: list[float], odr: str = "0x0F - 500 Hz"):
+        lines = [
+            f"# odr={odr}",
+            "sensor_uptime_s,temp_c,acc_x_g,acc_y_g,acc_z_g,gyro_x_dps,gyro_y_dps,gyro_z_dps",
+        ]
+        lines.extend(f"{time},28,0,0,1,0,0,0" for time in times)
+        path.write_text("\n".join(lines), encoding="utf-8-sig")
+
+    def test_counts_missing_frames_from_odr_period(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "imu.csv"
+            self._write_csv(path, [0.0, 0.002, 0.008])
+
+            result = analyze_imu_frame_loss.analyze_file(path)
+
+        self.assertEqual(result.received_frames, 3)
+        self.assertEqual(result.missing_frames, 2)
+        self.assertEqual(result.expected_frames, 5)
+        self.assertAlmostEqual(result.loss_rate, 0.4)
+        self.assertEqual(result.segment_count, 1)
+
+    def test_device_restart_starts_new_segment_without_loss(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "imu.csv"
+            self._write_csv(path, [1.0, 1.002, 0.0, 0.002])
+
+            result = analyze_imu_frame_loss.analyze_file(path)
+
+        self.assertEqual(result.missing_frames, 0)
+        self.assertEqual(result.segment_count, 2)
+
+    def test_non_integral_period_gap_reports_data_row(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "imu.csv"
+            self._write_csv(path, [0.0, 0.003])
+
+            with self.assertRaisesRegex(ValueError, "data row 2.*0.003.*0.002"):
+                analyze_imu_frame_loss.analyze_file(path)
+
+    def test_missing_odr_metadata_fails_clearly(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "imu.csv"
+            self._write_csv(path, [0.0, 0.002], odr="unknown")
+
+            with self.assertRaisesRegex(ValueError, "odr.*Hz"):
+                analyze_imu_frame_loss.analyze_file(path)
+
+
+if __name__ == "__main__":
+    unittest.main()