wrote some unit tests!

test/test_all.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python
+import unittest
+
+# For convenience
+import sys,os
+sys.path.insert(0, os.getcwd())
+sys.path.insert(0, os.path.join(os.getcwd(), os.pardir))
+
+# Import unit test cases or suites here
+from test_tileobj import TileTest
+from test_dirtytiles import DirtyTilesTest
+
+if __name__ == "__main__":
+    unittest.main()