1 files changed, 34 insertions, 4 deletions

diff --git a/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp b/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp
index d50677314df..97b88bc787a 100644
--- a/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp
+++ b/searchlib/src/tests/tensor/hnsw_index/hnsw_index_test.cpp
@@ -111,7 +111,7 @@ class MyBoundDistanceFunction : public BoundDistanceFunction {
     std::unique_ptr<BoundDistanceFunction> _real;
 
 public:
-    MyBoundDistanceFunction(std::unique_ptr<BoundDistanceFunction> real)
+    explicit MyBoundDistanceFunction(std::unique_ptr<BoundDistanceFunction> real)
         : _real(std::move(real))
     {
     }
@@ -147,19 +147,19 @@ class MyDistanceFunctionFactory : public DistanceFunctionFactory
 {
     std::unique_ptr<DistanceFunctionFactory> _real;
 public:
-    MyDistanceFunctionFactory(std::unique_ptr<DistanceFunctionFactory> real)
+    explicit MyDistanceFunctionFactory(std::unique_ptr<DistanceFunctionFactory> real)
         : _real(std::move(real))
     {
     }
 
     ~MyDistanceFunctionFactory() override;
 
-    std::unique_ptr<BoundDistanceFunction> for_query_vector(TypedCells lhs) override {
+    std::unique_ptr<BoundDistanceFunction> for_query_vector(TypedCells lhs) const override {
         EXPECT_FALSE(lhs.non_existing_attribute_value());
         return std::make_unique<MyBoundDistanceFunction>(_real->for_query_vector(lhs));
     }
 
-    std::unique_ptr<BoundDistanceFunction> for_insertion_vector(TypedCells lhs) override {
+    std::unique_ptr<BoundDistanceFunction> for_insertion_vector(TypedCells lhs) const override {
         EXPECT_FALSE(lhs.non_existing_attribute_value());
         return std::make_unique<MyBoundDistanceFunction>(_real->for_insertion_vector(lhs));
     }
@@ -936,6 +936,36 @@ TYPED_TEST(HnswIndexTest, search_during_remove)
     this->expect_top_3_by_docid("{0, 0}", {0, 0}, {7});
 }
 
+TYPED_TEST(HnswIndexTest, inconsistent_index)
+{
+    this->init(false);
+    this->vectors.clear();
+    this->vectors.set(1, {1, 3}).set(2, {7, 1}).set(3, {6, 5}).set(4, {8, 3}).set(5, {10, 3});
+    this->add_document(1);
+    this->add_document(2);
+    this->add_document(3);
+    this->add_document(4);
+    this->add_document(5);
+    this->expect_entry_point(1, 0);
+    this->expect_level_0(1, {2, 3});
+    this->expect_level_0(2, {1, 3, 4, 5});
+    this->expect_level_0(3, {1, 2, 4});
+    this->expect_level_0(4, {2, 3, 5});
+    this->expect_level_0(5, {2, 4});
+    EXPECT_EQ(0, this->index->check_consistency(6));
+    // Remove vector for docid 5 but don't update index.
+    this->vectors.clear(5);
+    EXPECT_EQ(1, this->index->check_consistency(6));
+    /*
+     * Removing document 2 causes mutual reconnect for nodes [1, 3, 4, 5]
+     * where nodes 1 and 5 are not previously connected. Distance from
+     * node 1 to node 5 cannot be calculated due to missing vector.
+     */
+    this->remove_document(2);
+    // No reconnect for node without vector
+    this->expect_level_0(5, {4});
+}
+
 using HnswMultiIndexTest = HnswIndexTest<HnswIndex<HnswIndexType::MULTI>>;
 
 namespace {