--- a
+++ b/tests/test.simulation.py
@@ -0,0 +1,16 @@
+from osim.env import L2RunEnv
+import numpy as np
+import unittest
+
+class SimulationTest(unittest.TestCase):
+    def test1(self):
+        
+        env = L2RunEnv(visualize=False)
+        observation = env.reset()
+
+        action = env.action_space.sample()
+        action[5] = np.NaN
+        self.assertRaises(ValueError, env.step, action)
+
+if __name__ == '__main__':
+    unittest.main()