diff --git a/test/test_black_box.py b/test/test_black_box.py
index 74985ac..bfde2fb 100644
--- a/test/test_black_box.py
+++ b/test/test_black_box.py
@@ -124,12 +124,12 @@ def test_length(mp_type: str, env_wrap: Tuple[str, Type[RawInterfaceWrapper]]):
                             {'phase_generator_type': 'exp'},
                             {'basis_generator_type': basis_generator_type})
 
-    for _ in range(5):
+    for i in range(5):
         env.reset()
         _obs, _reward, _terminated, _truncated, info = env.step(env.action_space.sample())
         length = info['trajectory_length']
 
-        assert length == env.spec.max_episode_steps
+        assert length == env.spec.max_episode_steps, f'Expcted total simulation length ({length}) to be equal to spec.max_episode_steps ({env.spec.max_episode_steps}), but was not during test nr. {i}'
 
 
 @pytest.mark.parametrize('mp_type', ['promp', 'dmp', 'prodmp'])
diff --git a/test/utils.py b/test/utils.py
index 2402f98..86e82a2 100644
--- a/test/utils.py
+++ b/test/utils.py
@@ -76,7 +76,7 @@ def run_env_determinism(env_id: str, seed: int, iterations: int = None, wrappers
     for i, time_step in enumerate(zip(*traj1, *traj2)):
         obs1, rwd1, term1, trunc1, ac1, obs2, rwd2, term2, trunc2, ac2 = time_step
         assert np.allclose(
-            obs1, obs2), f"Observations [{i}] {obs1} ({obs1.shape}) and {obs2} ({obs2.shape}) do not match."
+            obs1, obs2), f"Observations [{i}] {obs1} ({obs1.shape}) and {obs2} ({obs2.shape}) do not match: Biggest difference is {np.abs(obs1-obs2).max()} at index {np.abs(obs1-obs2).argmax()}."
         assert np.array_equal(
             ac1, ac2), f"Actions [{i}] {ac1} and {ac2} do not match."
         assert np.array_equal(
@@ -89,7 +89,7 @@ def run_env_determinism(env_id: str, seed: int, iterations: int = None, wrappers
 
 def verify_observations(obs, observation_space: gym.Space, obs_type="reset()"):
     assert observation_space.contains(obs), \
-        f"Observation {obs} received from {obs_type} not contained in observation space {observation_space}."
+        f"Observation {obs} ({obs.shape}) received from {obs_type} not contained in observation space {observation_space}."
 
 
 def verify_reward(reward):