--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/autodiff.py	Fri Jan 01 20:54:05 2010 +0100
@@ -0,0 +1,46 @@
+# Extension dedicated to test patch.diff() upgrade modes
+#
+#
+from mercurial import cmdutil, patch, util
+
+def autodiff(ui, repo, *pats, **opts):
+    diffopts = patch.diffopts(ui, opts)
+    git = opts.get('git', 'no')
+    brokenfiles = set()
+    losedatafn = None
+    if git in ('yes', 'no'):
+        diffopts.git = git == 'yes'
+        diffopts.upgrade = False
+    elif git == 'auto':
+        diffopts.git = False
+        diffopts.upgrade = True
+    elif git == 'warn':
+        diffopts.git = False
+        diffopts.upgrade = True
+        def losedatafn(fn=None, **kwargs):
+            brokenfiles.add(fn)
+            return True
+    elif git == 'abort':
+        diffopts.git = False
+        diffopts.upgrade = True
+        def losedatafn(fn=None, **kwargs):
+            raise util.Abort('losing data for %s' % fn)
+    else:
+        raise util.Abort('--git must be yes, no or auto')
+
+    node1, node2 = cmdutil.revpair(repo, [])
+    m = cmdutil.match(repo, pats, opts)
+    it = patch.diff(repo, node1, node2, match=m, opts=diffopts,
+                    losedatafn=losedatafn)
+    for chunk in it:
+        ui.write(chunk)
+    for fn in sorted(brokenfiles):
+        ui.write('data lost for: %s\n' % fn)
+
+cmdtable = {
+    "autodiff":
+        (autodiff,
+         [('', 'git', '', 'git upgrade mode (yes/no/auto/warn/abort)'),
+          ],
+         '[OPTION]... [FILE]...'),
+}