adding back files to be reviewed

tests/__init__.py

@@ -0,0 +1,15 @@
+from contextlib import contextmanager
+import os
+import tempfile
+
+
+@contextmanager
+def cdtemp():
+    """Context manager to change to/return from a tmpdir."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        cwd = os.getcwd()
+        try:
+            os.chdir(tmpdir)
+            yield
+        finally:
+            os.chdir(cwd)