Add test coverage for analyze_single_patent auto-download path

7 test cases covering:
- PDF on disk analyzed directly (no download)
- Auto-download from cached metadata link when PDF missing
- FileNotFoundError when no cached link available
- Cached patent without pdf_link raises FileNotFoundError
- Analysis pipeline failure returns error string gracefully
- Model override parameter forwarded to LLM
- FileNotFoundError during parsing re-raised (not swallowed)

Closes leeworks-agents/SPARC#1661

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/test_analyze_single_patent.py

@@ -0,0 +1,211 @@
+"""Tests for analyze_single_patent auto-download path.
+
+Covers issue #1661:
+- PDF exists on disk: direct analysis (happy path)
+- PDF not on disk, cached link exists: auto-download and analyze
+- PDF not on disk, no cached link: FileNotFoundError
+- Analysis failure after PDF found: graceful error message
+- Model override parameter passthrough
+"""
+
+import os
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from SPARC.analyzer import CompanyAnalyzer
+from SPARC.types import Patent
+
+
+@pytest.fixture(autouse=True)
+def mock_db(mocker):
+    """Mock DatabaseClient so no real DB is needed."""
+    mock_db_cls = mocker.patch("SPARC.analyzer.DatabaseClient")
+    mock_db_instance = MagicMock()
+    mock_db_instance.get_cached_patent.return_value = None
+    mock_db_instance.get_cached_serp_query.return_value = None
+    mock_db_cls.return_value = mock_db_instance
+    return mock_db_instance
+
+
+@pytest.fixture
+def analyzer(mocker, mock_db):
+    """Create a CompanyAnalyzer with mocked LLM and DB."""
+    mocker.patch("SPARC.analyzer.LLMAnalyzer")
+    return CompanyAnalyzer(openrouter_api_key="test-key")
+
+
+class TestAnalyzeSinglePatentAutoDownload:
+    """Test the auto-download logic in analyze_single_patent."""
+
+    def test_pdf_on_disk_analyzed_directly(self, analyzer, mocker, tmp_path):
+        """When PDF exists on disk, it is analyzed directly without download."""
+        patent_id = "US-11234567-B2"
+
+        # Create the patents dir and PDF file
+        patents_dir = tmp_path / "patents"
+        patents_dir.mkdir()
+        pdf_path = patents_dir / f"{patent_id}.pdf"
+        pdf_path.write_bytes(b"fake PDF content")
+
+        mock_parse = mocker.patch("SPARC.analyzer.SERP.parse_patent_pdf")
+        mock_minimize = mocker.patch("SPARC.analyzer.SERP.minimize_patent_for_llm")
+        mock_parse.return_value = {"abstract": "test", "claims": "test claims"}
+        mock_minimize.return_value = "minimized content"
+        analyzer.llm_analyzer.analyze_patent_content.return_value = "Good patent."
+
+        # Change cwd so patents/{patent_id}.pdf resolves to our tmp_path
+        original_cwd = os.getcwd()
+        os.chdir(tmp_path)
+        try:
+            result = analyzer.analyze_single_patent(patent_id, "TestCo")
+        finally:
+            os.chdir(original_cwd)
+
+        assert result == "Good patent."
+        # DB cache should not have been queried since file existed
+        analyzer.db.get_cached_patent.assert_not_called()
+
+    def test_auto_download_from_cached_link(self, analyzer, mocker, tmp_path):
+        """When PDF is not on disk but link is cached, auto-download occurs."""
+        patent_id = "US-99887766-A1"
+
+        # No patents dir exists (PDF not on disk)
+        mock_save = mocker.patch("SPARC.analyzer.SERP.save_patents")
+        downloaded_patent = Patent(patent_id=patent_id, pdf_link="https://example.com/patent.pdf")
+        downloaded_patent.pdf_path = f"patents/{patent_id}.pdf"
+        mock_save.return_value = downloaded_patent
+
+        # Cached patent has a PDF link
+        analyzer.db.get_cached_patent.return_value = {
+            "patent_id": patent_id,
+            "pdf_link": "https://example.com/patent.pdf",
+        }
+
+        # Mock the rest of the analysis pipeline
+        mock_parse = mocker.patch("SPARC.analyzer.SERP.parse_patent_pdf")
+        mock_minimize = mocker.patch("SPARC.analyzer.SERP.minimize_patent_for_llm")
+        mock_parse.return_value = {"abstract": "test abstract"}
+        mock_minimize.return_value = "minimized content"
+        analyzer.llm_analyzer.analyze_patent_content.return_value = "Strong innovation."
+
+        # Change cwd so patents/{patent_id}.pdf does NOT exist
+        original_cwd = os.getcwd()
+        os.chdir(tmp_path)
+        try:
+            result = analyzer.analyze_single_patent(patent_id, "DownloadCo")
+        finally:
+            os.chdir(original_cwd)
+
+        assert result == "Strong innovation."
+        analyzer.db.get_cached_patent.assert_called_once_with(patent_id)
+        mock_save.assert_called_once()
+        # Verify the Patent passed to save_patents has the correct ID and link
+        saved_patent = mock_save.call_args[0][0]
+        assert saved_patent.patent_id == patent_id
+        assert saved_patent.pdf_link == "https://example.com/patent.pdf"
+
+    def test_no_cached_link_raises_file_not_found(self, analyzer, mocker, tmp_path):
+        """When PDF is not on disk and no cached link, FileNotFoundError raised."""
+        patent_id = "US-00000000-X1"
+
+        analyzer.db.get_cached_patent.return_value = None
+
+        original_cwd = os.getcwd()
+        os.chdir(tmp_path)
+        try:
+            with pytest.raises(FileNotFoundError, match="no download link is cached"):
+                analyzer.analyze_single_patent(patent_id, "MissingCo")
+        finally:
+            os.chdir(original_cwd)
+
+    def test_cached_patent_without_pdf_link_raises(self, analyzer, mocker, tmp_path):
+        """When cached patent exists but has no pdf_link, FileNotFoundError raised."""
+        patent_id = "US-11111111-B1"
+
+        analyzer.db.get_cached_patent.return_value = {
+            "patent_id": patent_id,
+            "pdf_link": None,
+        }
+
+        original_cwd = os.getcwd()
+        os.chdir(tmp_path)
+        try:
+            with pytest.raises(FileNotFoundError, match="no download link is cached"):
+                analyzer.analyze_single_patent(patent_id, "NoPDFCo")
+        finally:
+            os.chdir(original_cwd)
+
+    def test_analysis_exception_returns_error_message(self, analyzer, mocker, tmp_path):
+        """When analysis pipeline fails, returns error string instead of raising."""
+        patent_id = "US-22222222-A2"
+
+        # Create the PDF on disk so it skips download
+        patents_dir = tmp_path / "patents"
+        patents_dir.mkdir()
+        (patents_dir / f"{patent_id}.pdf").write_bytes(b"fake PDF")
+
+        # Parse fails
+        mocker.patch(
+            "SPARC.analyzer.SERP.parse_patent_pdf",
+            side_effect=ValueError("Corrupt PDF"),
+        )
+
+        original_cwd = os.getcwd()
+        os.chdir(tmp_path)
+        try:
+            result = analyzer.analyze_single_patent(patent_id, "ErrorCo")
+        finally:
+            os.chdir(original_cwd)
+
+        assert "Failed to analyze patent" in result
+        assert "Corrupt PDF" in result
+
+    def test_model_override_passed_to_llm(self, analyzer, mocker, tmp_path):
+        """The model parameter is forwarded to the LLM analyzer."""
+        patent_id = "US-33333333-B2"
+
+        patents_dir = tmp_path / "patents"
+        patents_dir.mkdir()
+        (patents_dir / f"{patent_id}.pdf").write_bytes(b"fake PDF")
+
+        mocker.patch("SPARC.analyzer.SERP.parse_patent_pdf", return_value={"abstract": "test"})
+        mocker.patch("SPARC.analyzer.SERP.minimize_patent_for_llm", return_value="content")
+        analyzer.llm_analyzer.analyze_patent_content.return_value = "Analysis result."
+
+        original_cwd = os.getcwd()
+        os.chdir(tmp_path)
+        try:
+            result = analyzer.analyze_single_patent(
+                patent_id, "ModelCo", model="openai/gpt-4o"
+            )
+        finally:
+            os.chdir(original_cwd)
+
+        assert result == "Analysis result."
+        analyzer.llm_analyzer.analyze_patent_content.assert_called_once_with(
+            patent_content="content",
+            company_name="ModelCo",
+            model="openai/gpt-4o",
+        )
+
+    def test_file_not_found_during_parse_re_raised(self, analyzer, mocker, tmp_path):
+        """FileNotFoundError during parsing is re-raised, not caught."""
+        patent_id = "US-44444444-C1"
+
+        patents_dir = tmp_path / "patents"
+        patents_dir.mkdir()
+        (patents_dir / f"{patent_id}.pdf").write_bytes(b"fake PDF")
+
+        mocker.patch(
+            "SPARC.analyzer.SERP.parse_patent_pdf",
+            side_effect=FileNotFoundError("PDF file vanished"),
+        )
+
+        original_cwd = os.getcwd()
+        os.chdir(tmp_path)
+        try:
+            with pytest.raises(FileNotFoundError, match="PDF file vanished"):
+                analyzer.analyze_single_patent(patent_id, "VanishCo")
+        finally:
+            os.chdir(original_cwd)