def test_extract_citations_edge_cases(self):
        """Test edge cases for citation extraction."""
        # Define local extract_citations for testing that follows the core implementation
        def local_extract_citations(text):
            # Handle None or empty input
            if text is None or text == "":
                return []

            # Match the core implementation pattern: 7-8 alphanumeric chars
            citation_pattern = re.compile(r"\[([A-Za-z0-9]{7,8})\]")

            sids = []
            for match in citation_pattern.finditer(text):
                sid = match.group(1)
                sids.append(sid)

            return sids

        # Citations at beginning or end of text
        text = "[abc1234] at the beginning and at the end [def5678]"
        citations = local_extract_citations(text)
        assert citations == ["abc1234", "def5678"], "Should extract citations at beginning and end"

        # Empty text
        text = ""
        citations = local_extract_citations(text)
        assert citations == [], "Should handle empty text gracefully"

        # None input
        citations = local_extract_citations(None)
        assert citations == [], "Should handle None input gracefully"

        # Text with brackets but no valid citation format
        text = "Text with [short] but no valid citation format."
        citations = local_extract_citations(text)
        assert citations == [], "Should not extract non-citation brackets (too short)"

        # Text with brackets but wrong length
        text = "Text with [abc123] (too short) and [abcdefghi] (too long)."
        citations = local_extract_citations(text)
        assert citations == [], "Should not extract brackets with wrong length"

        # Text with brackets that have correct length but non-alphanumeric chars
        text = "Text with [abc-1234] has the right length but contains special characters."
        citations = local_extract_citations(text)
        assert citations == [], "Should not extract brackets with special characters"

        # Text with close brackets only
        text = "Text with close brackets only]."
        citations = local_extract_citations(text)
        assert citations == [], "Should not extract when only close brackets present"
Test edge cases for citation extraction.
py/tests/unit/retrieval/test_citations.py