test: assert pacing actually varies; document NoPacing as policy base

tests/unit/test_pacing.py

@@ -24,15 +24,21 @@ class TestHumanPacing:
     def test_unknown_action_has_no_delay(self):
         assert HumanPacing().delay("unknown-action") == 0.0
 
+    def test_delays_actually_vary(self):
+        assert len({HumanPacing().delay("text") for _ in range(50)}) > 1
+
     def test_click_offset_stays_inside_element(self):
         p = HumanPacing()
+        offsets = []
         for _ in range(200):
             offset = p.click_offset(100, 40)
             assert offset is not None
+            offsets.append(offset)
             x, y = offset
             # offsets are measured from the element CENTER (selenium 4)
             assert -49 <= x <= 49
             assert -19 <= y <= 19
+        assert any(o != (0, 0) for o in offsets)
 
     def test_tiny_elements_get_plain_click(self):
         p = HumanPacing()