--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/atomic/writer.py	Fri Jan 02 13:22:09 2015 -0800
@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+
+"""
+write a file atomically
+"""
+
+# imports
+import os
+import shutil
+import tempfile
+
+# module globals
+__all__ = ['ensure_dir', 'write']
+
+def ensure_dir(directory):
+    """ensure a directory exists"""
+    if os.path.exists(directory):
+        if not os.path.isdir(directory):
+            raise OSError("Not a directory: '{}'".format(directory))
+        return directory
+    os.makedirs(directory)
+    return directory
+
+
+def write(contents, path):
+    """atomically write a file taking advantage of move"""
+
+    path = os.path.abspath(path)
+    fd, tmp_path = tempfile.mkstemp()
+    os.write(fd, contents)
+    os.close(fd)
+    ensure_dir(os.path.dirname(path))
+    shutil.move(tmp_path, path)

--- a/tests/test_atomicwrite.py	Fri Jan 02 13:08:39 2015 -0800
+++ b/tests/test_atomicwrite.py	Fri Jan 02 13:22:09 2015 -0800
@@ -4,8 +4,8 @@
 unit tests for AtomicWrite
 """
 
+import atomic
 import os
-import sys
 import tempfile
 import unittest
 
@@ -14,6 +14,9 @@
     def test_atomicwrite(self):
         tf = tempfile.mktemp()
         self.assertFalse(os.path.exists(tf))
+        atomic.write('foo', tf)
+        self.assertTrue(os.path.exists(tf))
+        self.assertEqual(open(tf, 'r').read(), 'foo')
 
 if __name__ == '__main__':
     unittest.main()