Merge pull request 'Replace test_fixup_256 with a regression test for the Node256 fixupMaxVersion false-Commit bug' (#90) from weaselbot/conflict-set:weaselbot/issue-89 into main

Reviewed-on: #90

test_conflict_set.py

@@ -251,13 +251,18 @@ def test_merge_child_node48():
         cs.addWrites(1, write(b"\x00" * 8, b"\x00" * 10))
 
 
-def test_fixup_256():
+def test_fixup_256_heterogeneous_versions():
+    # Regression test for issue #89: recomputing the maxVersion of a Node256
+    # must consider all of its children, not just those with an index < 16.
+    # Here the highest-version child ("\x10\x50") has an index >= 16, and the
+    # range write ends at the Node256, which erases that child from the range
+    # and recomputes the Node256's maxVersion.
     with DebugConflictSet() as cs:
-        cs.addWrites(0, write(bytes([1])))
         for i in range(256):
-            cs.addWrites(1, write(bytes([1, i])))
-        cs.addWrites(2, write(bytes([0]), bytes([1])))
-        cs.check(read(0, bytes([1]), bytes([2])))
+            cs.addWrites(1, write(bytes([0x10, i])))
+        cs.addWrites(10, write(bytes([0x10, 0x50])))
+        cs.addWrites(11, write(bytes([0x05]), bytes([0x10])))
+        assert cs.check(read(5, bytes([0x10, 0x50]))) == [Result.CONFLICT]
 
 
 def test_large_removal_buffer():