Added test checking that flatland can be called from a multiprocessing pool

tests/test_flatland_multiprocessing.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+from multiprocessing.pool import Pool
+
+from flatland.envs.observations import TreeObsForRailEnv
+from flatland.envs.predictions import ShortestPathPredictorForRailEnv
+from flatland.envs.rail_env import RailEnv
+from flatland.envs.rail_generators import rail_from_grid_transition_map
+from flatland.envs.schedule_generators import random_schedule_generator
+from flatland.utils.simple_rail import make_simple_rail
+
+"""Tests for `flatland` package."""
+
+
+def test_multiprocessing_tree_obs():
+    number_of_agents = 5
+    rail, rail_map = make_simple_rail()
+
+    obs_builder = TreeObsForRailEnv(max_depth=2, predictor=ShortestPathPredictorForRailEnv())
+
+    env = RailEnv(width=rail_map.shape[1], height=rail_map.shape[0], rail_generator=rail_from_grid_transition_map(rail),
+                  schedule_generator=random_schedule_generator(), number_of_agents=number_of_agents,
+                  obs_builder_object=obs_builder)
+    env.reset(True, True)
+
+    pool = Pool()
+    pool.map(obs_builder.get, range(number_of_agents))
+
+
+def main():
+    test_multiprocessing_tree_obs()
+
+
+if __name__ == "__main__":
+    main()