108536234: created users and roles data and domain model.

You will need to run the /scripts/bootstrap.sh to create the database for test and the app.

tests/app/main/dao/test_roles_dao.py

@@ -0,0 +1,21 @@
+import pytest
+import sqlalchemy
+
+from app.models import Roles
+from app.main.dao import roles_dao
+
+
+def test_insert_role_should_be_able_to_get_role(notifications_admin, notifications_admin_db):
+    role = Roles(id=1000, role='some role for test')
+    roles_dao.insert_role(role)
+
+    saved_role = roles_dao.get_role_by_id(role.id)
+    assert saved_role == role
+
+
+def test_insert_role_will_throw_error_if_role_already_exists():
+    role = Roles(id=1, role='cannot create a duplicate')
+
+    with pytest.raises(sqlalchemy.exc.IntegrityError) as error:
+        roles_dao.insert_role(role)
+    assert 'duplicate key value violates unique constraint "roles_pkey"' in str(error.value)