--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-rust-revlog.py	Mon Dec 23 10:02:50 2019 -0800
@@ -0,0 +1,34 @@
+from __future__ import absolute_import
+import unittest
+
+try:
+    from mercurial import rustext
+
+    rustext.__name__  # trigger immediate actual import
+except ImportError:
+    rustext = None
+else:
+    from mercurial.rustext import revlog
+
+from mercurial.testing import revlog as revlogtesting
+
+
+@unittest.skipIf(
+    rustext is None, "rustext module revlog relies on is not available",
+)
+class RustRevlogIndexTest(revlogtesting.RevlogBasedTestBase):
+    def test_heads(self):
+        idx = self.parseindex()
+        rustidx = revlog.MixedIndex(idx)
+        self.assertEqual(rustidx.headrevs(), idx.headrevs())
+
+    def test_len(self):
+        idx = self.parseindex()
+        rustidx = revlog.MixedIndex(idx)
+        self.assertEqual(len(rustidx), len(idx))
+
+
+if __name__ == '__main__':
+    import silenttestrunner
+
+    silenttestrunner.main(__name__)