Update sync codes

tests/test_synthetic.py

@@ -0,0 +1,27 @@
+#####################################################
+# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2021.03 #
+#####################################################
+# pytest tests/test_synthetic.py -s                 #
+#####################################################
+import sys, random
+import unittest
+import pytest
+from pathlib import Path
+
+lib_dir = (Path(__file__).parent / ".." / "lib").resolve()
+print("library path: {:}".format(lib_dir))
+if str(lib_dir) not in sys.path:
+    sys.path.insert(0, str(lib_dir))
+
+from datasets import SynAdaptiveEnv
+
+
+class TestSynAdaptiveEnv(unittest.TestCase):
+    """Test the synethtic adaptive environment."""
+
+    def test_simple(self):
+        dataset = SynAdaptiveEnv()
+        for i, (idx, t, x) in enumerate(dataset):
+            assert i == idx, "First loop: {:} vs {:}".format(i, idx)
+        for i, (idx, t, x) in enumerate(dataset):
+            assert i == idx, "Second loop: {:} vs {:}".format(i, idx)