我在让Chai的expect.to.thrownode.js应用程序进行测试时遇到问题。测试会因引发的错误而不断失败,但是如果我将测试用例包装在try和catch中并断言所捕获的错误,它将起作用。
expect.to.throw
难道expect.to.throw不喜欢的工作,我认为它应该还是什么?
it('should throw an error if you try to get an undefined property', function (done) { var params = { a: 'test', b: 'test', c: 'test' }; var model = new TestModel(MOCK_REQUEST, params); // neither of these work expect(model.get('z')).to.throw('Property does not exist in model schema.'); expect(model.get('z')).to.throw(new Error('Property does not exist in model schema.')); // this works try { model.get('z'); } catch(err) { expect(err).to.eql(new Error('Property does not exist in model schema.')); } done(); });
失败:
19 passing (25ms) 1 failing 1) Model Base should throw an error if you try to get an undefined property: Error: Property does not exist in model schema.
您必须将一个函数传递给expect。像这样:
expect
expect(model.get.bind(model, 'z')).to.throw('Property does not exist in model schema.'); expect(model.get.bind(model, 'z')).to.throw(new Error('Property does not exist in model schema.'));
执行此操作的方式将传递给call expect的 结果model.get('z')。但是要测试是否抛出了某些东西,您必须将一个函数传递给expect,该函数expect会自行调用。bind上面使用的方法创建了一个新函数,当调用该函数时,将model.get使用this设置为的值model和设置为的第一个参数进行调用'z'。
model.get('z')
bind
model.get
this
model
'z'
bind可以在这里找到对它的很好的解释。