fix(qa): preserve final CSV pair row number (#16433)

test/unit_test/rag/app/test_qa_csv.py

@@ -0,0 +1,54 @@
+#
+#  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+from __future__ import annotations
+
+import warnings
+
+with warnings.catch_warnings():
+    warnings.filterwarnings("ignore", message=".*pkg_resources is deprecated.*", category=UserWarning)
+    import pkg_resources  # noqa: F401 - stabilize xgboost import during collection
+
+import pytest
+
+from rag.app import qa
+
+
+def _noop_callback(*_args, **_kwargs):
+    pass
+
+
+@pytest.fixture(autouse=True)
+def _stub_rag_tokenizer(monkeypatch):
+    def fake_tokenize(text):
+        return str(text)
+
+    monkeypatch.setattr("rag.nlp.rag_tokenizer.tokenize", fake_tokenize)
+    monkeypatch.setattr("rag.nlp.rag_tokenizer.fine_grained_tokenize", fake_tokenize)
+
+
+@pytest.mark.p2
+def test_csv_final_pair_uses_last_line_number():
+    chunks = qa.chunk(
+        "qa.csv",
+        binary=b"Question 1,Answer 1\nQuestion 2,Answer 2",
+        lang="English",
+        callback=_noop_callback,
+    )
+
+    assert len(chunks) == 2
+    assert chunks[0]["top_int"] == [1]
+    assert chunks[1]["top_int"] == [2]