node.js 如何解决“ReferenceError: expect is not defined”错误消息？
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How can I solve "ReferenceError: expect is not defined" error message?
提问by sensorario
I am trying to test Javascript with mocha. I've this snippet of code:
我正在尝试用 mocha 测试 Javascript。我有这段代码：
describe('Array', function() {
describe('indexOf()', function() {
it("dovrebbe tornare -1 quando l'elemento non è presente", function() {
expect([1,2,3].indexOf(4)).to.equal(-1)
})
})
})
and a test/array.jsfile. Mocha was installed with
和一个test/array.js文件。摩卡安装了
$ npm install -g mocha
When I run
当我跑
$ mocha
I get this error:
我收到此错误：
$ mocha
?
0 passing (5ms)
1 failing
1) Array indexOf() dovrebbe tornare -1 quando l'elemento non è presente:
ReferenceError: expect is not defined
at Context.<anonymous> (/Users/simonegentili/Desktop/Javascipt Best Practice/test/array.js:4:4)
at Test.Runnable.run (/usr/local/lib/node_modules/mocha/lib/runnable.js:211:32)
at Runner.runTest (/usr/local/lib/node_modules/mocha/lib/runner.js:358:10)
at /usr/local/lib/node_modules/mocha/lib/runner.js:404:12
at next (/usr/local/lib/node_modules/mocha/lib/runner.js:284:14)
at /usr/local/lib/node_modules/mocha/lib/runner.js:293:7
at next (/usr/local/lib/node_modules/mocha/lib/runner.js:237:23)
at Object._onImmediate (/usr/local/lib/node_modules/mocha/lib/runner.js:261:5)
at processImmediate [as _immediateCallback] (timers.js:317:15)
回答by Dan Heberden
Mocha is a test framework; you need to provide your own assertion lib as https://mochajs.org/#assertionsstates. Thus, expectis indeed undefined because you never defined it.
Mocha 是一个测试框架；您需要提供自己的断言库，如https://mochajs.org/#assertions所述。因此，expect确实是未定义的，因为您从未定义过它。
(I recommend chai)
（我推荐柴）
npm install chai
then
然后
(see Amit Choukroune's comment pointing out to actually require chai)
（见 Amit Choukroune 的评论指出实际上需要柴）
then
然后
var expect = chai.expect;
回答by Paul Rad
Try
尝试
First, in the terminal
首先，在终端
npm install expect.js
npm install expect.js
And in your code:
在你的代码中：
var expect = require('expect');
回答by dmchk
After you install Chai as other posts suggest, with the es6 syntax you should put the import at the top
按照其他帖子的建议安装 Chai 后，使用 es6 语法，您应该将导入放在顶部
import {expect} from 'chai';
回答by shael
let chai = require('chai');
var assert = chai.assert;
describe('Array', function() {
describe('#indexOf()', function() {
it('should return -1 when the value is not present', function() {
assert.equal(-1, [1, 2, 3].indexOf(4));
});
});
});
回答by micrub
In order to expose expectglobally, while using chai, following should be loaded by means of configuration for your prefered testing library:
为了在expect全局公开，在使用时chai，应通过配置为您首选的测试库加载以下内容：
require('chai/register-assert'); // Using Assert style
require('chai/register-expect'); // Using Expect style
require('chai/register-should'); // Using Should style
For example:
例如：
npx mocha --config .mocharc.js *.spec.js
npx mocha --config .mocharc.js *.spec.js
回答by PDHide
Create a file chaiexpections.js and declare expect as global
创建文件 chaiexpections.js 并声明 expect 为全局
'use strict';
// Configure chai
global.expect = require('chai').expect;
Now pass it in config file under cucumberopts, require
现在在cucumberopts下的配置文件中传递它，需要
cucumberOpts: {
require: ['./testsuites/*.js','./chaiexpections.js','./commons/hooks.js']
//tags: [],
strict: true,
format: [],
'dry-run': false,
compiler: [],
format: 'json:results.json',
},
This prevents the overhead of having to declare chai exception in each stepdefinition
这可以防止必须在每个步骤定义中声明 chai 异常的开销
回答by ASHISH RANJAN
Either add this script tag in html file
在 html 文件中添加这个脚本标签
<script src="https://unpkg.com/expect@%3C21/umd/expect.min.js"></script>
or install package
或安装包
npm install chai or expect
回答by ALoK VeRMa
Install Expect.js or Chai.js if you are using Mocha for TDD
如果您使用 Mocha 进行 TDD，请安装 Expect.js 或 Chai.js
So, do npm install expector npm install chai
所以，做npm install expect或npm install chai
回答by RMorrisey
In my use case, I was running a mocha spec through karma. The solution was to install the karma integrations for my test framework libs:
在我的用例中，我通过karma. 解决方案是为我的测试框架库安装 karma 集成：
npm install karma-mocha --save-dev
npm install karma-sinon-chai --save-dev
...and also to add the frameworks to my karma.conf.js:
...并将框架添加到我的karma.conf.js：
module.exports = function(config) {
config.set({
browsers: ['Chrome'],
frameworks: ['mocha', 'sinon-chai'],
files: [
'.tmp/**/*.spec.js'
],
client: {
chai: {
includeStack: true
},
mocha: {
reporter: 'html',
ui: 'bdd'
}
}
})
}
Hope this helps someone else.
希望这对其他人有帮助。
