Add test for PettingZoo API

tests/test_pettingzoo.py

@@ -0,0 +1,20 @@
+"""
+Test that our custom environment works according to the PettingZoo Parallel API.
+"""
+
+
+import unittest
+from pettingzoo.test import parallel_api_test
+
+from smartgrid import make_basic_smartgrid
+
+
+class TestPettingZoo(unittest.TestCase):
+
+    def test_parallel_api(self):
+        env = make_basic_smartgrid(max_step=10_000)
+        parallel_api_test(env, num_cycles=1_000)
+
+
+if __name__ == '__main__':
+    unittest.main()