--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/printrevset.py	Fri Aug 10 02:02:40 2018 -0400
@@ -0,0 +1,41 @@
+from __future__ import absolute_import
+from mercurial import (
+  cmdutil,
+  commands,
+  extensions,
+  logcmdutil,
+  revsetlang,
+  smartset,
+)
+
+from mercurial.utils import (
+  stringutil,
+)
+
+def logrevset(repo, pats, opts):
+    revs = logcmdutil._initialrevs(repo, opts)
+    if not revs:
+        return None
+    match, pats, slowpath = logcmdutil._makematcher(repo, revs, pats, opts)
+    return logcmdutil._makerevset(repo, match, pats, slowpath, opts)
+
+def uisetup(ui):
+    def printrevset(orig, repo, pats, opts):
+        revs, filematcher = orig(repo, pats, opts)
+        if opts.get(b'print_revset'):
+            expr = logrevset(repo, pats, opts)
+            if expr:
+                tree = revsetlang.parse(expr)
+                tree = revsetlang.analyze(tree)
+            else:
+                tree = []
+            ui = repo.ui
+            ui.write(b'%s\n' % stringutil.pprint(opts.get(b'rev', [])))
+            ui.write(revsetlang.prettyformat(tree) + b'\n')
+            ui.write(stringutil.prettyrepr(revs) + b'\n')
+            revs = smartset.baseset()  # display no revisions
+        return revs, filematcher
+    extensions.wrapfunction(logcmdutil, 'getrevs', printrevset)
+    aliases, entry = cmdutil.findcmd(b'log', commands.table)
+    entry[1].append((b'', b'print-revset', False,
+                     b'print generated revset and exit (DEPRECATED)'))