ai-agent-book 精选快照（<2MB 代码与文档，来自 github.com/bojieli/ai-agent-book）

tests/test_ch3_bm25_reindex_doc.py

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+import pytest
+"""Regression test: re-indexing an existing doc_id in InvertedIndex must clear old terms and not inflate total_documents."""
+import os
+import sys
+
+sys.path.insert(0, os.path.abspath("chapter3/sparse-embedding"))
+
+from bm25_engine import InvertedIndex, BM25  # noqa: E402
+
+
+def test_reindex_maintains_doc_count_and_clears_stale_terms():
+    index = InvertedIndex()
+    index.add_document(1, "python database sql")
+    assert index.total_documents == 1
+    assert index.get_posting_list("database") == {1}
+    assert index.document_frequency["database"] == 1
+
+    # Re-index doc 1 with completely different terms
+    index.add_document(1, "python web fasta")
+    assert index.total_documents == 1
+    assert index.get_posting_list("database") == set()
+    assert "database" not in index.document_frequency
+    assert index.get_posting_list("web") == {1}
+    assert index.document_frequency["web"] == 1
+
+
+def test_reindex_search_engine_bm25_scores():
+    index = InvertedIndex()
+    index.add_document(10, "machine learning deep learning")
+    index.add_document(20, "quantum computing physics")
+    assert index.total_documents == 2
+
+    bm25 = BM25(index)
+    results_before = bm25.search("machine learning")
+    assert len(results_before) == 1
+    assert results_before[0][0] == 10
+
+    # Update document 10 to quantum physics
+    index.add_document(10, "quantum physics mechanics")
+    assert index.total_documents == 2
+
+    # Search for machine learning should yield 0 results
+    results_after_old = bm25.search("machine learning")
+    assert len(results_after_old) == 0
+
+    # Search for quantum should yield both 10 and 20
+    results_after_new = bm25.search("quantum")
+    doc_ids = {r[0] for r in results_after_new}
+    assert doc_ids == {10, 20}