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_zero_avgdl.py

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+import pytest
+import os
+import sys
+
+sys.path.insert(0, os.path.abspath("chapter3/sparse-embedding"))
+
+from collections import Counter
+from bm25_engine import InvertedIndex, BM25
+
+
+def test_bm25_calculate_term_score_zero_avgdl():
+    """Prove that calculating term score when avgdl is 0 handles division by zero safely."""
+    index = InvertedIndex()
+    bm25 = BM25(index)
+    assert bm25.avgdl == 0
+    index.term_frequency[1] = Counter({"python": 2})
+    index.doc_lengths[1] = 5
+    index.index["python"].add(1)
+
+    score = bm25.calculate_term_score("python", doc_id=1)
+    assert isinstance(score, float)
+
+
+def test_bm25_calculate_raw_idf_n_less_than_df():
+    """Prove that calculate_raw_idf when total_documents N < df does not raise math domain error."""
+    index = InvertedIndex()
+    index.index["python"].add(1)
+    bm25 = BM25(index)
+
+    idf = bm25.calculate_raw_idf("python")
+    assert isinstance(idf, float)