merge: R-B (Crossref references as third citation fallback)

tests/sources/test_crossref.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import httpx
 import pytest
 
+from codex.models import Citation
 from codex.sources import crossref
 
 
@@ -48,3 +49,56 @@ def test_fetch_abstract_404_returns_none(monkeypatch: pytest.MonkeyPatch) -> Non
 
     monkeypatch.setattr(crossref, "_get", mock_get)
     assert crossref.fetch_abstract("10.0000/nonexistent") is None
+
+
+# ---------------------------------------------------------------------------
+# fetch_references (roadmap R-B)
+# ---------------------------------------------------------------------------
+
+
+def test_fetch_references_returns_doi_edges(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Only references carrying a DOI become Citations; citing_id is the queried DOI."""
+    body = {
+        "message": {
+            "reference": [
+                {"key": "ref1", "DOI": "10.1090/s0002-9947-04-03545-7"},
+                {"key": "ref2", "unstructured": "A book with no DOI, 1992."},  # skipped
+                {"key": "ref3", "DOI": "10.1007/bf02392449", "article-title": "X"},
+            ]
+        }
+    }
+
+    def mock_get(url: str, params: dict[str, object] | None = None) -> httpx.Response:
+        return httpx.Response(200, json=body)
+
+    monkeypatch.setattr(crossref, "_get", mock_get)
+    refs = crossref.fetch_references("10.1007/s00454-019-00132-8")
+
+    assert refs == [
+        Citation(citing_id="10.1007/s00454-019-00132-8", cited_id="10.1090/s0002-9947-04-03545-7"),
+        Citation(citing_id="10.1007/s00454-019-00132-8", cited_id="10.1007/bf02392449"),
+    ]
+
+
+def test_fetch_references_no_reference_key_returns_empty(monkeypatch: pytest.MonkeyPatch) -> None:
+    """A work with no deposited reference list returns []."""
+
+    def mock_get(url: str, params: dict[str, object] | None = None) -> httpx.Response:
+        return httpx.Response(200, json={"message": {"title": ["No refs deposited"]}})
+
+    monkeypatch.setattr(crossref, "_get", mock_get)
+    assert crossref.fetch_references("10.1007/978-3-642-17413-1_7") == []
+
+
+def test_fetch_references_404_returns_empty(monkeypatch: pytest.MonkeyPatch) -> None:
+    """A 404 returns [] rather than raising."""
+
+    def mock_get(url: str, params: dict[str, object] | None = None) -> httpx.Response:
+        raise httpx.HTTPStatusError(
+            "404",
+            request=httpx.Request("GET", url),
+            response=httpx.Response(404, request=httpx.Request("GET", url)),
+        )
+
+    monkeypatch.setattr(crossref, "_get", mock_get)
+    assert crossref.fetch_references("10.0000/nonexistent") == []