diff --git a/tests/fakepatchtime.py b/tests/fakepatchtime.py
new file mode 100644
--- /dev/null
+++ b/tests/fakepatchtime.py
@@ -0,0 +1,26 @@
+# extension to emulate invoking 'patch.internalpatch()' at the time
+# specified by '[fakepatchtime] fakenow'
+
+from mercurial import extensions, patch as patchmod, util
+
+def internalpatch(orig, ui, repo, patchobj, strip,
+                  prefix='', files=None,
+                  eolmode='strict', similarity=0):
+    if files is None:
+        files = set()
+    r = orig(ui, repo, patchobj, strip,
+             prefix=prefix, files=files,
+             eolmode=eolmode, similarity=similarity)
+
+    fakenow = ui.config('fakepatchtime', 'fakenow')
+    if fakenow:
+        # parsing 'fakenow' in YYYYmmddHHMM format makes comparison between
+        # 'fakenow' value and 'touch -t YYYYmmddHHMM' argument easy
+        fakenow = util.parsedate(fakenow, ['%Y%m%d%H%M'])[0]
+        for f in files:
+            repo.wvfs.utime(f, (fakenow, fakenow))
+
+    return r
+
+def extsetup(ui):
+    extensions.wrapfunction(patchmod, 'internalpatch', internalpatch)