test(fhir): add regression tests for empty and dangling-reference Bundle edges

tests/unit/clinical/test_fhir_bundle_edge_cases.py

@@ -0,0 +1,109 @@
+"""Regression tests for FHIR Bundle edge cases (openmed#547).
+
+These tests lock in behaviors that are already correctly implemented but
+were not explicitly verified: empty input handling and dangling reference
+preservation.
+"""
+
+from openmed.clinical.exporters.fhir import to_bundle
+
+
+class TestEmptyInput:
+    """Verify to_bundle handles empty resource lists correctly."""
+
+    def test_empty_resources_returns_well_formed_transaction_bundle(self):
+        bundle = to_bundle([], doc_id="empty")
+        assert bundle["resourceType"] == "Bundle"
+        assert bundle["type"] == "transaction"
+        assert bundle["entry"] == []
+
+    def test_empty_resources_collection_bundle(self):
+        bundle = to_bundle([], doc_id="empty", bundle_type="collection")
+        assert bundle["resourceType"] == "Bundle"
+        assert bundle["type"] == "collection"
+        assert bundle["entry"] == []
+
+    def test_empty_resources_batch_bundle(self):
+        bundle = to_bundle([], doc_id="empty", bundle_type="batch")
+        assert bundle["type"] == "batch"
+        assert bundle["entry"] == []
+
+
+class TestDanglingReferences:
+    """Verify references to absent resources are preserved verbatim."""
+
+    def test_dangling_reference_preserved_verbatim(self):
+        """A reference to a resource not in the Bundle is left unchanged."""
+        resources = [
+            {
+                "resourceType": "Condition",
+                "id": "cond1",
+                "subject": {"reference": "Patient/absent"},
+            },
+        ]
+        bundle = to_bundle(resources, doc_id="doc-1")
+        condition = bundle["entry"][0]["resource"]
+        assert condition["subject"]["reference"] == "Patient/absent"
+
+    def test_mixed_internal_and_dangling_references(self):
+        """Internal references are rewritten; external ones are preserved."""
+        resources = [
+            {
+                "resourceType": "Patient",
+                "id": "pat1",
+            },
+            {
+                "resourceType": "Condition",
+                "id": "cond1",
+                "subject": {"reference": "Patient/pat1"},  # internal
+                "encounter": {"reference": "Encounter/missing"},  # dangling
+                "evidence": [
+                    {"detail": [{"reference": "Observation/absent"}]}  # dangling
+                ],
+            },
+        ]
+        bundle = to_bundle(resources, doc_id="mixed-refs")
+
+        # Find the rewritten URLs
+        patient_url = next(
+            entry["fullUrl"]
+            for entry in bundle["entry"]
+            if entry["resource"]["resourceType"] == "Patient"
+        )
+
+        condition = next(
+            entry["resource"]
+            for entry in bundle["entry"]
+            if entry["resource"]["resourceType"] == "Condition"
+        )
+
+        # Internal reference rewritten
+        assert condition["subject"]["reference"] == patient_url
+
+        # Dangling references preserved verbatim
+        assert condition["encounter"]["reference"] == "Encounter/missing"
+        assert (
+            condition["evidence"][0]["detail"][0]["reference"] == "Observation/absent"
+        )
+
+    def test_multiple_dangling_references_same_resource(self):
+        """Multiple dangling references on one resource are all preserved."""
+        resources = [
+            {
+                "resourceType": "DiagnosticReport",
+                "id": "report1",
+                "subject": {"reference": "Patient/gone"},
+                "performer": [{"reference": "Practitioner/absent"}],
+                "result": [
+                    {"reference": "Observation/missing1"},
+                    {"reference": "Observation/missing2"},
+                ],
+            },
+        ]
+        bundle = to_bundle(resources, doc_id="multi-dangling")
+        report = bundle["entry"][0]["resource"]
+
+        assert report["subject"]["reference"] == "Patient/gone"
+        assert report["performer"][0]["reference"] == "Practitioner/absent"
+        assert report["result"][0]["reference"] == "Observation/missing1"
+        assert report["result"][1]["reference"] == "Observation/missing2"