Endpoint to return a ServiceContactList for a given id.

app/dao/service_contact_list_dao.py

@@ -2,6 +2,15 @@ from app import db
 from app.models import ServiceContactList
 
 
+def dao_get_contact_list_by_id(service_id, contact_list_id):
+    contact_list = ServiceContactList.query.filter_by(
+        service_id=service_id,
+        id=contact_list_id
+    ).one()
+
+    return contact_list
+
+
 def dao_get_contact_lists(service_id):
     contact_lists = ServiceContactList.query.filter_by(
         service_id=service_id

app/service/rest.py

@@ -36,7 +36,8 @@ from app.dao.returned_letters_dao import (
     fetch_returned_letter_summary,
     fetch_returned_letters,
 )
-from app.dao.service_contact_list_dao import dao_get_contact_lists, save_service_contact_list
+from app.dao.service_contact_list_dao import dao_get_contact_lists, save_service_contact_list, \
+    dao_get_contact_list_by_id
 from app.dao.service_data_retention_dao import (
     fetch_service_data_retention,
     fetch_service_data_retention_by_id,
@@ -1023,6 +1024,16 @@ def get_contact_list(service_id):
     return jsonify([x.serialize() for x in contact_lists])
 
 
+@service_blueprint.route('/<uuid:service_id>/contact-list/<uuid:contact_list_id>', methods=['GET'])
+def get_contact_list_by_id(service_id, contact_list_id):
+    contact_list = dao_get_contact_list_by_id(
+        service_id=service_id,
+        contact_list_id=contact_list_id
+    )
+
+    return jsonify(contact_list.serialize())
+
+
 @service_blueprint.route('/<uuid:service_id>/contact-list', methods=['POST'])
 def create_contact_list(service_id):
     service_contact_list = validate(request.get_json(), create_service_contact_list_schema)

tests/app/service/test_service_contact_list_rest.py

@@ -79,3 +79,37 @@ def test_get_contact_list_returns_for_service(admin_request, notify_db_session):
     assert len(response) == 2
     assert response[0] == expected_list_2.serialize()
     assert response[1] == expected_list_1.serialize()
+
+
+def test_dao_get_contact_list_by_id(admin_request, sample_service):
+    service_1 = create_service(service_name='Service under test')
+
+    expected_list_1 = create_service_contact_list(service=service_1)
+    create_service_contact_list(service=service_1)
+
+    response = admin_request.get(
+        'service.get_contact_list_by_id',
+        service_id=service_1.id,
+        contact_list_id=expected_list_1.id
+    )
+
+    assert response == expected_list_1.serialize()
+
+
+def test_dao_get_contact_list_by_id_does_not_return_if_contact_list_id_for_another_service(
+    admin_request, sample_service
+):
+    service_1 = create_service(service_name='Service requesting list')
+    service_2 = create_service(service_name='Service that owns the list')
+
+    create_service_contact_list(service=service_1)
+    list_2 = create_service_contact_list(service=service_2)
+
+    response = admin_request.get(
+        'service.get_contact_list_by_id',
+        service_id=service_1.id,
+        contact_list_id=list_2.id,
+        _expected_status=404
+    )
+
+    assert response['message'] == "No result found"