require('module-alias/register'); require('babel-plugin-rewire'); const command = require('@Commands/Roll'); //const exec = command.__get__('exec'); describe('roll command', () => { const reply = jest.fn(str => str); const message = { author: { tag: 'test' }, reply: reply }; it('should not return anything without correct arguments', () => { const args = ['1w6']; expect(command.exec(message, args)).resolves.toBeUndefined(); expect(reply).toHaveBeenCalled(); }); });