Implement DDS exercise, customer UI and local demo

tests/test_load_dds.py

@@ -0,0 +1,26 @@
+"""Small offline checks for the load probe's measurement and safety logic."""
+
+import importlib.util
+import unittest
+from pathlib import Path
+
+
+SCRIPT = Path(__file__).resolve().parents[1] / "scripts" / "load_dds.py"
+SPEC = importlib.util.spec_from_file_location("load_dds", SCRIPT)
+load_dds = importlib.util.module_from_spec(SPEC)
+SPEC.loader.exec_module(load_dds)
+
+
+class PercentileTests(unittest.TestCase):
+    def test_empty(self):
+        self.assertIsNone(load_dds.percentile([], 95))
+
+    def test_nearest_rank_p95(self):
+        self.assertEqual(load_dds.percentile(list(range(1, 101)), 95), 95)
+
+    def test_single_sample(self):
+        self.assertEqual(load_dds.percentile([12.5], 95), 12.5)
+
+
+if __name__ == "__main__":
+    unittest.main()