Guard held passive yaw events in ordinary Python CI

docs/coverage.json

@@ -1,6 +1,6 @@
 {
   "schemaVersion": 1,
   "label": "Test coverage",
-  "message": "66%",
+  "message": "67%",
   "color": "orange"
 }

tests/test_passive_yaw_held_portable.py

@@ -0,0 +1,43 @@
+"""Keep held-heading event behavior available in ordinary Python CI."""
+
+import numpy as np
+
+from wecsim.hydrodynamics.passiveYaw import (
+    HeldPassiveYawExcitation, SampledPassiveYawExcitation,
+)
+
+
+def test_held_heading_commits_only_accepted_states_and_wraps_at_zero():
+    directions = np.arange(0.0, 360.0, 10.0)
+    times = np.arange(6) * 0.01
+    force_grid = np.zeros((len(times), 1, len(directions), 6))
+    force_grid[:, 0, :, 5] = directions
+    sampled = SampledPassiveYawExcitation(
+        times, directions, np.array([10.0]), force_grid, np.zeros(len(times)),
+    )
+    held = HeldPassiveYawExcitation(sampled, threshold=1.0)
+
+    # These headings exercise initialization between BEM samples, a hold,
+    # snapping to a tabulated heading at the inclusive threshold, an update,
+    # and the 0/360-degree boundary. Yaw torque is unchanged by frame rotation.
+    yaw_degrees = (2.0, 2.5, 0.0, 1.0, 2.0, 11.0)
+    expected_headings = (8.0, 8.0, 10.0, 10.0, 8.0, 0.0)
+    for step, (time, yaw_degrees_at_time, expected) in enumerate(zip(
+        times, yaw_degrees, expected_headings,
+    )):
+        coordinate = np.array([np.deg2rad(yaw_degrees_at_time)])
+        before = held.last_heading
+        trial_force = held(time, coordinate, np.zeros(1))
+        assert trial_force[5] == expected
+        assert held.last_heading == before
+        assert len(held.force_history) == step
+
+        held.commit(time, coordinate)
+        assert held.last_heading == expected
+        np.testing.assert_allclose(held.force_history[-1], trial_force,
+                                   rtol=0, atol=1e-12)
+
+    np.testing.assert_allclose(
+        np.asarray(held.force_history)[:, 5], expected_headings,
+        rtol=0, atol=1e-12,
+    )