Add test to test deterministic simulation when seed is given

tests/test_mal_simulator.py

@@ -1,11 +1,12 @@
 """Test MalSimulator class"""
 
+import pytest
+
 from maltoolbox.attackgraph import AttackGraph, Attacker
 from malsim.sims.mal_simulator import MalSimulator
 from malsim.scenario import load_scenario, create_simulator_from_scenario
 from malsim.sims import MalSimulatorSettings
 
-
 def test_malsimulator(corelang_lang_graph, model):
     attack_graph = AttackGraph(corelang_lang_graph, model)
     MalSimulator(corelang_lang_graph, model, attack_graph)
@@ -990,6 +991,67 @@ def test_default_settings_defender_observation_false_negatives():
     assert not defender_obs_state[node_index]
 
 
+def test_default_settings_defender_observation_false_negatives_seed():
+    """Test default MalSimulator with false negative rates"""
+
+    def run_simulation_with_seed(
+            seed,
+            expected_attacker_obs,
+            expected_defender_obs
+        ):
+        sim.reset(seed=seed)
+        attacker_agent_id = next(iter(sim.get_attacker_agents()))
+        defender_agent_id = next(iter(sim.get_defender_agents()))
+
+        # Get an uncompromised step
+        user_3_compromise = sim.attack_graph.get_node_by_full_name(
+            'User:3:compromise')
+
+        # Let the attacker compromise User:3:compromise
+        actions = {
+            attacker_agent_id: (1, sim._id_to_index[user_3_compromise.id]),
+            defender_agent_id: (0, None)}
+
+        obs, _, _, _, _ = sim.step(actions)
+
+        actual_attacker_obs_state = obs[attacker_agent_id]['observed_state']
+        for index, state in enumerate(actual_attacker_obs_state):
+            assert state == expected_attacker_obs[index]
+
+        actual_defender_obs_state = obs[defender_agent_id]['observed_state']
+        for index, state in enumerate(actual_defender_obs_state):
+            assert state == expected_defender_obs[index]
+
+    sim, _ = create_simulator_from_scenario(
+        'tests/testdata/scenarios/traininglang_fp_fn_scenario.yml',
+    )
+
+    expected_attacker_obs_100 = \
+        [-1,  0,  1,  0, -1, -1, -1, -1, -1, -1, -1, -1,  1,  1, -1]
+    expected_defender_obs_100 = \
+        [0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0]
+    seed = 100
+
+    # Make sure the seed makes the obs state deterministic
+    # in terms of false positives
+    for _ in range(100):
+        # running it many times with same seed
+        # yields same observations
+        run_simulation_with_seed(
+            seed,
+            expected_attacker_obs_100,
+            expected_defender_obs_100
+        )
+
+    with pytest.raises(AssertionError):
+        # running it once with different seed
+        # yields assertion error (different observations)
+        run_simulation_with_seed(
+            1337,
+            expected_attacker_obs_100,
+            expected_defender_obs_100
+        )
+
 def test_defender_observation_false_positives_negatives():
     """Test default MalSimulator with false negative and positive rates"""