--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-rust-revlog.py	Sun Dec 22 20:26:57 2024 +0100
@@ -0,0 +1,97 @@
+import struct
+
+from mercurial.node import (
+    bin as node_bin,
+    hex,
+)
+
+try:
+    from mercurial import rustext
+
+    rustext.__name__  # trigger immediate actual import
+except ImportError:
+    rustext = None
+else:
+    # this would fail already without appropriate ancestor.__package__
+    from mercurial.rustext.ancestor import LazyAncestors
+
+from mercurial.testing import revlog as revlogtesting
+
+header = struct.unpack(">I", revlogtesting.data_non_inlined[:4])[0]
+
+
+class RustInnerRevlogTestMixin:
+    """Common tests for both Rust Python bindings."""
+
+    node_hex0 = b'd1f4bbb0befc13bd8cd39d0fcdd93b8c078c4a2f'
+    node0 = node_bin(node_hex0)
+
+
+# Conditional skipping done by the base class
+class RustInnerRevlogTest(
+    revlogtesting.RustRevlogBasedTestBase, RustInnerRevlogTestMixin
+):
+    """For reference"""
+
+    def test_heads(self):
+        idx = self.parserustindex()
+        self.assertEqual(idx.headrevs(), [3])
+
+    def test_len(self):
+        idx = self.parserustindex()
+        self.assertEqual(len(idx), 4)
+
+    def test_ancestors(self):
+        rustidx = self.parserustindex()
+        lazy = LazyAncestors(rustidx, [3], 0, True)
+        # we have two more references to the index:
+        # - in its inner iterator for __contains__ and __bool__
+        # - in the LazyAncestors instance itself (to spawn new iterators)
+        self.assertTrue(2 in lazy)
+        self.assertTrue(bool(lazy))
+        self.assertEqual(list(lazy), [3, 2, 1, 0])
+        # a second time to validate that we spawn new iterators
+        self.assertEqual(list(lazy), [3, 2, 1, 0])
+
+        # let's check bool for an empty one
+        self.assertFalse(LazyAncestors(rustidx, [0], 0, False))
+
+    def test_standalone_nodetree(self):
+        idx = self.parserustindex()
+        nt = self.nodetree(idx)
+        for i in range(4):
+            nt.insert(i)
+
+        bin_nodes = [entry[7] for entry in idx]
+        hex_nodes = [hex(n) for n in bin_nodes]
+
+        for i, node in enumerate(hex_nodes):
+            self.assertEqual(nt.prefix_rev_lookup(node), i)
+            self.assertEqual(nt.prefix_rev_lookup(node[:5]), i)
+
+        # all 4 revisions in idx (standard data set) have different
+        # first nybbles in their Node IDs,
+        # hence `nt.shortest()` should return 1 for them, except when
+        # the leading nybble is 0 (ambiguity with NULL_NODE)
+        for i, (bin_node, hex_node) in enumerate(zip(bin_nodes, hex_nodes)):
+            shortest = nt.shortest(bin_node)
+            expected = 2 if hex_node[0] == ord('0') else 1
+            self.assertEqual(shortest, expected)
+            self.assertEqual(nt.prefix_rev_lookup(hex_node[:shortest]), i)
+
+        # test invalidation (generation poisoning) detection
+        del idx[3]
+        self.assertTrue(nt.is_invalidated())
+
+
+# Conditional skipping done by the base class
+class PyO3InnerRevlogTest(
+    revlogtesting.PyO3RevlogBasedTestBase, RustInnerRevlogTestMixin
+):
+    """Testing new PyO3 bindings, by comparison with rust-cpython bindings."""
+
+
+if __name__ == '__main__':
+    import silenttestrunner
+
+    silenttestrunner.main(__name__)