diff --git a/tests/core/test_common_utils.py b/tests/core/test_common_utils.py
index 2d1aff0c..e4355fc5 100644
--- a/tests/core/test_common_utils.py
+++ b/tests/core/test_common_utils.py
@@ -1,3 +1,4 @@
+import numpy as np
 import omegaconf
 import pytest
 
@@ -130,3 +131,58 @@ def _check_shapes(train_cap):
     assert isinstance(val, replay_buffer.IterableReplayBuffer)
 
     _check_shapes(1500)
+
+
+class MockModelEnv:
+    def __init__(self):
+        self.obs = None
+
+    def reset(self, obs0, propagation_method=None, return_as_np=None):
+        self.obs = obs0
+        return obs0
+
+    def step(self, action, sample=None):
+        next_obs = self.obs + action[:, :1]
+        reward = np.ones(next_obs.shape[0])
+        done = np.zeros(next_obs.shape[0])
+        self.obs = next_obs
+        return next_obs, reward, done, {}
+
+
+class MockAgent:
+    def __init__(self, length):
+        self.actions = np.ones((length, 1))
+
+    def plan(self, obs):
+        return self.actions
+
+
+def test_rollout_model_env():
+    obs_size = 10
+    plan_length = 20
+    num_samples = 5
+    model_env = MockModelEnv()
+    obs0 = np.zeros(obs_size)
+    agent = MockAgent(plan_length)
+    plan = 0 * agent.plan(obs0)  # this should be ignored
+
+    # Check rolling out with an agent
+    obs, rewards, actions = utils.rollout_model_env(
+        model_env, obs0, plan, agent, num_samples=num_samples
+    )
+
+    assert obs.shape == (plan_length + 1, num_samples, obs_size)
+    assert rewards.shape == (plan_length, num_samples)
+    assert actions.shape == (plan_length, 1)
+
+    for i, o in enumerate(obs):
+        assert o.min() == i
+
+    # Check rolling out with a given plan
+    plan = 2 * agent.plan(obs0)
+    obs, rewards, actions = utils.rollout_model_env(
+        model_env, obs0, plan, None, num_samples=num_samples
+    )
+
+    for i, o in enumerate(obs):
+        assert o.min() == 2 * i