test persistence - added, file name typo in tests fixed

tests/test_flatland_envs_persistence.py

+import numpy as np
+
+from flatland.envs.rail_env import RailEnv
+from flatland.envs.rail_generators import rail_from_grid_transition_map
+from flatland.envs.line_generators import sparse_line_generator
+from flatland.utils.simple_rail import make_simple_rail
+from flatland.envs.persistence import RailEnvPersister
+
+def test_load_new():
+
+    filename = "test_load_new.pkl"
+
+    rail, rail_map, optionals = make_simple_rail()
+    n_agents = 2
+    env_initial = RailEnv(width=rail_map.shape[1], height=rail_map.shape[0], rail_generator=rail_from_grid_transition_map(rail, optionals),
+                  line_generator=sparse_line_generator(), number_of_agents=n_agents)
+    env_initial.reset(False, False)
+
+    rails_initial = env_initial.rail.grid
+    agents_initial = env_initial.agents
+
+    RailEnvPersister.save(env_initial, filename)
+
+    env_loaded, _ = RailEnvPersister.load_new(filename)
+
+    rails_loaded = env_loaded.rail.grid
+    agents_loaded = env_loaded.agents
+
+    assert np.all(np.array_equal(rails_initial, rails_loaded))
+    assert agents_initial == agents_loaded
+
+def main():
+    pass
+
+if __name__ == "__main__":
+    main()