t.test('--Scenario: save error (stubbed) [failure]', function (st) {
      st.plan(1);

      const userData = {
        email: 'valid@example.com',
        password: 'longpassword'
      };
      const user = User.forge(userData);

      const stub = sinon.stub(user, 'save', function () {
        throw Error('stubbed error');
      });

      return Promise.try(function () {
        return user.register();
      }).catch(function (error) {
        st.equal(
          error.message,
          'stubbed error',
          'should respond with stubbed error'
        );
        stub.restore();
      });
    });