Check observed collection clocks before labeling fields

tests/unit/test_fig2_collection.py

@@ -182,6 +182,11 @@ class CollectionContracts(unittest.TestCase):
 
 
 class SelectionContracts(unittest.TestCase):
+    def test_recorded_clock_must_equal_observed_solver(self):
+        driver.check_clock(types.SimpleNamespace(step_count=4579200),4576000,3200)
+        with self.assertRaisesRegex(RuntimeError,'observed solver clock'):
+            driver.check_clock(types.SimpleNamespace(step_count=4579201),4576000,3200)
+
     @staticmethod
     def mean(ux, uy, indices):
         return dict(mean_ux=ux[indices].mean(axis=0), mean_uy=uy[indices].mean(axis=0))