Import upstream snapshot d424a0c899f6b33cbd3daeb279913134349c0b63

Upstream: https://github.com/pollen-robotics/microduck_rl
Upstream-Commit: d424a0c899f6b33cbd3daeb279913134349c0b63
Upstream-Branch: develop

tests/test_nan_guard.py

@@ -0,0 +1,66 @@
+"""robot_state_is_nan doit attraper un état non-fini n'importe où (joints OU base
+OU roues), pas seulement dans joint_pos — sinon un free-joint qui diverge en NaN
+échappe au reset et corrompt l'obs critic (base_lin_vel/wheel_vel), ce qui tue
+l'entraînement via le check_nan global de rsl_rl.
+"""
+
+import torch
+
+from mjlab_microduck.tasks.mdp import robot_state_is_nan
+
+
+class _Data:
+    def __init__(self, n):
+        self.joint_pos = torch.zeros(n, 4)
+        self.joint_vel = torch.zeros(n, 4)
+        self.root_link_pos_w = torch.zeros(n, 3)
+        self.root_link_quat_w = torch.zeros(n, 4)
+        self.root_link_lin_vel_w = torch.zeros(n, 3)
+        self.root_link_ang_vel_w = torch.zeros(n, 3)
+
+
+class _Asset:
+    def __init__(self, data):
+        self.data = data
+
+
+class _Scene:
+    def __init__(self, asset):
+        self._a = asset
+
+    def __getitem__(self, _key):
+        return self._a
+
+
+class _Env:
+    def __init__(self, data):
+        self.scene = _Scene(_Asset(data))
+
+
+def test_catches_base_linear_velocity_nan():
+    # env 1 : vitesse de base NaN (free-joint divergé) — joint_pos reste fini.
+    d = _Data(3)
+    d.root_link_lin_vel_w[1, 0] = float("nan")
+    out = robot_state_is_nan(_Env(d))
+    assert out.tolist() == [False, True, False]
+
+
+def test_catches_base_velocity_inf():
+    # inf dans la vitesse angulaire de base (avant qu'il ne devienne NaN).
+    d = _Data(2)
+    d.root_link_ang_vel_w[0, 2] = float("inf")
+    out = robot_state_is_nan(_Env(d))
+    assert out.tolist() == [True, False]
+
+
+def test_still_catches_joint_pos_nan():
+    # comportement historique préservé.
+    d = _Data(2)
+    d.joint_pos[0, 1] = float("nan")
+    out = robot_state_is_nan(_Env(d))
+    assert out.tolist() == [True, False]
+
+
+def test_clean_state_is_not_flagged():
+    out = robot_state_is_nan(_Env(_Data(4)))
+    assert out.tolist() == [False, False, False, False]