--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-atomictempfile.py	Sun Apr 24 19:25:10 2011 -0400
@@ -0,0 +1,49 @@
+import os
+import glob
+from mercurial.util import atomictempfile
+
+# basic usage
+def test1_simple():
+    if os.path.exists('foo'):
+        os.remove('foo')
+    file = atomictempfile('foo')
+    (dir, basename) = os.path.split(file._tempname)
+    assert not os.path.isfile('foo')
+    assert basename in glob.glob('.foo-*')
+
+    file.write('argh\n')
+    file.rename()
+
+    assert os.path.isfile('foo')
+    assert basename not in glob.glob('.foo-*')
+    print 'OK'
+
+# close() removes the temp file but does not make the write
+# permanent -- essentially discards your work (WTF?!)
+def test2_close():
+    if os.path.exists('foo'):
+        os.remove('foo')
+    file = atomictempfile('foo')
+    (dir, basename) = os.path.split(file._tempname)
+
+    file.write('yo\n')
+    file.close()
+
+    assert not os.path.isfile('foo')
+    assert basename not in os.listdir('.')
+    print 'OK'
+
+# if a programmer screws up and passes bad args to atomictempfile, they
+# get a plain ordinary TypeError, not infinite recursion
+def test3_oops():
+    try:
+        file = atomictempfile()
+    except TypeError:
+        print "OK"
+    else:
+        print "expected TypeError"
+
+if __name__ == '__main__':
+    test1_simple()
+    test2_close()
+    test3_oops()