[NDR-404] Add fhir handler get unit tests

lambdas/tests/unit/handlers/test_pdm_get_fhir_document_reference_by_id_handler.py

@@ -1,13 +1,18 @@
+import json
+from copy import deepcopy
+
 import pytest
+
+from enums.lambda_error import LambdaError
 from enums.mtls import MtlsCommonNames
 from enums.snomed_codes import SnomedCodes
 from handlers.get_fhir_document_reference_handler import (
-    extract_document_parameters,
     lambda_handler,
 )
 from models.document_reference import DocumentReference
 from tests.unit.conftest import TEST_UUID
 from tests.unit.helpers.data.dynamo.dynamo_responses import MOCK_SEARCH_RESPONSE
+from utils.lambda_exceptions import GetFhirDocumentReferenceException
 from utils.lambda_handler_utils import extract_bearer_token
 
 SNOMED_CODE = SnomedCodes.PATIENT_DATA.value.code
@@ -26,7 +31,7 @@
             "userAgent": "curl/7.64.1",
             "clientCert": {
                 "clientCertPem": "-----BEGIN CERTIFICATE-----...",
-                "subjectDN": "CN=ndrclient.main.int.pdm.national.nhs.uk,O=NHS,C=UK",
+                "subjectDN": "CN=ndrclient.main.dev.pdm.national.nhs.uk,O=NHS,C=UK",
                 "issuerDN": "CN=NHS Root CA,O=NHS,C=UK",
                 "serialNumber": "12:34:56",
                 "validity": {
@@ -39,40 +44,71 @@
 }
 
 MOCK_DOCUMENT_REFERENCE = DocumentReference.model_validate(
-    MOCK_SEARCH_RESPONSE["Items"][0]
+    MOCK_SEARCH_RESPONSE["Items"][0],
 )
 
 
 @pytest.fixture
 def mock_config_service(mocker):
     mock_config = mocker.patch(
-        "handlers.get_fhir_document_reference_handler.DynamicConfigurationService"
+        "handlers.get_fhir_document_reference_handler.DynamicConfigurationService",
     )
-    mock_config_instance = mock_config.return_value
-    return mock_config_instance
+    return mock_config.return_value
 
 
 @pytest.fixture
 def mock_document_service(mocker):
     mock_service = mocker.patch(
-        "handlers.get_fhir_document_reference_handler.GetFhirDocumentReferenceService"
+        "handlers.get_fhir_document_reference_handler.GetFhirDocumentReferenceService",
     )
-    mock_service_instance = mock_service.return_value
-    mock_service_instance.handle_get_document_reference_request.return_value = (
+    instance = mock_service.return_value
+    instance.handle_get_document_reference_request.return_value = (
         MOCK_DOCUMENT_REFERENCE
     )
-    return mock_service_instance
+    return instance
 
 
 @pytest.fixture
 def mock_mtls_common_names(monkeypatch):
     monkeypatch.setattr(
         MtlsCommonNames,
         "_get_mtls_common_names",
-        classmethod(lambda cls: {"PDM": ["ndrclient.main.int.pdm.national.nhs.uk"]}),
+        classmethod(lambda cls: {"PDM": ["ndrclient.main.dev.pdm.national.nhs.uk"]}),
+    )
+
+
+@pytest.fixture
+def mock_mtls_disallow_all(monkeypatch):
+    monkeypatch.setattr(
+        MtlsCommonNames,
+        "_get_mtls_common_names",
+        classmethod(lambda cls: {"PDM": []}),
     )
 
 
+@pytest.fixture
+def unauthorized_cn_event():
+    ev = deepcopy(MOCK_MTLS_VALID_EVENT)
+    ev["requestContext"]["identity"]["clientCert"][
+        "subjectDN"
+    ] = "CN=unauthorised.client.nhs.uk,O=NHS,C=UK"
+    return ev
+
+
+@pytest.fixture
+def event_missing_client_cert():
+    ev = deepcopy(MOCK_MTLS_VALID_EVENT)
+    ev["requestContext"]["identity"].pop("clientCert", None)
+    return ev
+
+
+@pytest.fixture
+def event_malformed_subject_dn():
+    ev = deepcopy(MOCK_MTLS_VALID_EVENT)
+    ev["requestContext"]["identity"]["clientCert"]["subjectDN"] = "O=NHS,C=UK"
+    return ev
+
+
 def test_lambda_handler_happy_path_with_mtls_pdm_login(
     set_env,
     mock_mtls_common_names,
@@ -87,12 +123,13 @@ def test_lambda_handler_happy_path_with_mtls_pdm_login(
 
     assert response["statusCode"] == 200
     assert response["body"] == "test_document_reference"
-    # Verify correct method calls
+
     mock_document_service.handle_get_document_reference_request.assert_called_once_with(
-        SNOMED_CODE, TEST_UUID
+        SNOMED_CODE,
+        TEST_UUID,
     )
     mock_document_service.create_document_reference_fhir_response.assert_called_once_with(
-        MOCK_DOCUMENT_REFERENCE
+        MOCK_DOCUMENT_REFERENCE,
     )
 
 
@@ -101,7 +138,86 @@ def test_extract_bearer_token_when_pdm(context, mock_mtls_common_names):
     assert token is None
 
 
-def test_extract_document_parameters_valid_pdm():
-    document_id, snomed_code = extract_document_parameters(MOCK_MTLS_VALID_EVENT)
-    assert document_id == TEST_UUID
-    assert snomed_code == SNOMED_CODE
+def test_lambda_handler_mtls_unauthorised_cn_returns_400(
+    set_env,
+    mock_mtls_disallow_all,
+    mock_document_service,
+    unauthorized_cn_event,
+    context,
+):
+    resp = lambda_handler(unauthorized_cn_event, context)
+    assert resp["statusCode"] == 400
+    mock_document_service.handle_get_document_reference_request.assert_not_called()
+
+
+def test_lambda_handler_mtls_missing_client_cert_returns_401(
+    set_env,
+    mock_mtls_disallow_all,
+    mock_document_service,
+    event_missing_client_cert,
+    context,
+):
+    resp = lambda_handler(event_missing_client_cert, context)
+    assert resp["statusCode"] == 401
+    mock_document_service.handle_get_document_reference_request.assert_not_called()
+
+
+def test_lambda_handler_mtls_malformed_subject_dn_returns_401(
+    set_env,
+    mock_mtls_disallow_all,
+    mock_document_service,
+    event_malformed_subject_dn,
+    context,
+):
+    resp = lambda_handler(event_malformed_subject_dn, context)
+    assert resp["statusCode"] == 401
+    mock_document_service.handle_get_document_reference_request.assert_not_called()
+
+
+def test_lambda_handler_mtls_invalid_path_parameters_returns_400(
+    set_env,
+    mock_mtls_common_names,
+    mock_document_service,
+    context,
+):
+    ev = deepcopy(MOCK_MTLS_VALID_EVENT)
+    ev["pathParameters"] = {"id": "invalid_format_no_tilde"}
+    resp = lambda_handler(ev, context)
+    assert resp["statusCode"] == 400
+    mock_document_service.handle_get_document_reference_request.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "status, lambda_error",
+    [
+        (404, LambdaError.DocumentReferenceNotFound),
+        (403, LambdaError.DocumentReferenceForbidden),
+        (400, LambdaError.DocumentReferenceMissingParameters),
+        (500, LambdaError.DocumentReferenceGeneralError),
+    ],
+)
+def test_lambda_handler_mtls_service_errors(
+    set_env,
+    mock_mtls_common_names,
+    mock_document_service,
+    context,
+    status,
+    lambda_error,
+):
+    mock_document_service.handle_get_document_reference_request.side_effect = (
+        GetFhirDocumentReferenceException(status, lambda_error)
+    )
+
+    resp = lambda_handler(MOCK_MTLS_VALID_EVENT, context)
+    assert resp["statusCode"] == status
+
+    body = json.loads(resp["body"])
+    assert body["resourceType"] == "OperationOutcome"
+    assert (
+        body["issue"][0]["details"]["coding"][0]["code"]
+        == lambda_error.value.get("fhir_coding").code
+    )
+    assert (
+        body["issue"][0]["details"]["coding"][0]["display"]
+        == lambda_error.value.get("fhir_coding").display
+    )