Unit testing in vuejs

Question

I am trying to configure/run my first unit test for Vuejs. But I can't get past the configuration issues. I have tried installing the libraries but for some reason I keep getting errors.

Here is what an example of my code looks like:

My directory structure:

   hello/
     dist/
     node_modules/
     src/
      components/
        hello.vue
     test/
      setup.js
      test.spec.js
    .babelrc
     package.json
     webpack.config.js

Contents inside my files

src/components/hello.vue

<template> <div> {{message}} </div> </template>
<script>
export default {
  name: 'hello',
  data () { return message: 'Hi' },
  created () {
    // ...
  }
}

test/setup.js

// setup JSDOM
require('jsdom-global')()

// make expect available globally
global.expect = require('expect')

test/test.spect.js

import { shallow } from 'vue/test-utils'
import  { hello} from '../../../src/components/hello.vue'

describe('hello', () => {
  // just testing simple data to see if it works
  expect(1).toBe(1)
})

.babelrc

{
  "env": {
    "development": {
      "presets": [
        [
          "env",
          {
            "modules": false
          }
        ]
      ]
    },
    "test": {
      "presets": [
        [
          "env",
          {
            "modules": false,
            "targets": {
              "node": "current"
            }
          }
        ]
      ],
      "plugins": [
        "istanbul"
      ]
    }
  }
}

package.json

...
  "scripts": {
    "build": "webpack -p",
    "test": "cross-env NODE_ENV=test nyc mocha-webpack --webpack-config webpack.config.js --require test/setup.js test/**/*.spec.js"
  },
"devDependencies": {
    "babel-core": "^6.26.0",
    "babel-loader": "^7.1.2",
    "babel-preset-env": "^1.6.1",
    "cross-env": "^5.1.1",
    "css-loader": "^0.28.7",
    "file-loader": "^1.1.5",
    "node-sass": "^4.7.2",
    "sass-loader": "^6.0.6",
    "vue-loader": "^13.5.0",
    "vue-template-compiler": "^2.5.9",
    "webpack": "^3.10.0",
    "webpack-dev-server": "^2.9.7",
    "jsdom": "^11.3.0",
    "jsdom-global": "^3.0.2",
    "mocha": "^3.5.3",
    "mocha-webpack": "^1.0.0-rc.1",
    "nyc": "^11.4.1",
    "expect": "^21.2.1",
    "@vue/test-utils": "^1.0.0-beta.12"
  },
  ...
"nyc": {
    "include": [
      "src/**/*.(js|vue)"
    ],
    "instrument": false,
    "sourceMap": false
  }

and finally my webpack.config.js ...

if(process.env.NODE_ENV == "test") {
  module.exports.externals = [ require ('webpack-node-externals')()]
  module.exports.devtool = 'inline-cheap-module-source-map'
}

now when I run npm test from my root folder hello/ I get this error:

> [email protected] test C:\Users\john\vue-learn\hello
> npm run e2e


> [email protected] e2e C:\Users\john\vue-learn\hello
> node test/e2e/runner.js

Starting selenium server... started - PID:  12212

[Test] Test Suite
=====================

Running:  default e2e tests
 × Timed out while waiting for element <#app> to be present for 5000 milliseconds.  - expected "visible" but got: "not found"
    at Object.defaultE2eTests [as default e2e tests] (C:/Users/john/Google Drive/lab/hello/test/e2e/specs/test.js:13:8)
    at _combinedTickCallback (internal/process/next_tick.js:131:7)


FAILED:  1 assertions failed (20.281s)

 _________________________________________________

 TEST FAILURE:  1 assertions failed, 0 passed. (20.456s)

 × test

   - default e2e tests (20.281s)
   Timed out while waiting for element <#app> to be present for 5000 milliseconds.  - expected "visible" but got: "not found"
       at Object.defaultE2eTests [as default e2e tests] (C:/Users/john/Google Drive/lab/hello/test/e2e/specs/test.js:13:8)
       at _combinedTickCallback (internal/process/next_tick.js:131:7)

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] e2e: `node test/e2e/runner.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] e2e script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\john\AppData\Roaming\npm-cache\_logs\2018-04-03T23_53_15_976Z-debug.log
npm ERR! Test failed.  See above for more details.

I don't know why this happens. When I installed my webpack project at first I didn't install a testing library with the npm init command so there are no conflicts, but still I get that error:

update (after bounty)

I'm just trying to test my vuejs application. Hopefully with jasmine/karma. If anyone knows how to integrate these into a simple app and run the firsts test, I can take it from there. My problem is not writing tests but configuring it

Answer 1

So first thing you didn't need to enable the end to end testing in your project. I would say start fresh

$ npm install -g vue-cli
$ vue init webpack vue-testing

? Project name vue-testing
? Project description A Vue.js project
? Author Tarun Lalwani <[email protected]>
? Vue build standalone
? Install vue-router? Yes
? Use ESLint to lint your code? Yes
? Pick an ESLint preset Standard
? Set up unit tests Yes
? Pick a test runner karma
? Setup e2e tests with Nightwatch? No
? Should we run `npm install` for you after the project has been created? (recommended) yarn

Say N to Setup e2e tests with Nightwatch and use Karma for the Pick a test runner.

$ npm test

> [email protected] test /Users/tarun.lalwani/Desktop/tarunlalwani.com/tarunlalwani/workshop/ub16/so/vue-testing
> npm run unit


> [email protected] unit /Users/tarun.lalwani/Desktop/tarunlalwani.com/tarunlalwani/workshop/ub16/so/vue-testing
> cross-env BABEL_ENV=test karma start test/unit/karma.conf.js --single-run

07 04 2018 21:35:28.620:INFO [karma]: Karma v1.7.1 server started at http://0.0.0.0:9876/
07 04 2018 21:35:28.629:INFO [launcher]: Launching browser PhantomJS with unlimited concurrency
07 04 2018 21:35:28.645:INFO [launcher]: Starting browser PhantomJS
07 04 2018 21:35:32.891:INFO [PhantomJS 2.1.1 (Mac OS X 0.0.0)]: Connected on socket M1HeZIiOis3eE3mLAAAA with id 44927405

  HelloWorld.vue
    ✓ should render correct contents

PhantomJS 2.1.1 (Mac OS X 0.0.0): Executed 1 of 1 SUCCESS (0.061 secs / 0.041 secs)
TOTAL: 1 SUCCESS


=============================== Coverage summary ===============================
Statements   : 100% ( 2/2 )
Branches     : 100% ( 0/0 )
Functions    : 100% ( 0/0 )
Lines        : 100% ( 2/2 )
================================================================================

Now your npm test would work fine.

Answer 2

According to the error logs you provide here, the failing tests that you spot are the End to End ones. Indeed, by executing the command npm test e2e you're testing using Nightwatch. See under /tests/e2e/specs. Here you should have a default test file checking that your Vue application properly create a DOM element identified as app.

The test should be the following:

// For authoring Nightwatch tests, see
// http://nightwatchjs.org/guide#usage

module.exports = {
  'default e2e tests': function (browser) {
    // automatically uses dev Server port from /config.index.js
    // default: http://localhost:8080
    // see nightwatch.conf.js
    const devServer = browser.globals.devServerURL

    browser
      .url(devServer)
      .waitForElementVisible('#app', 5000)
      .assert.elementPresent('.hello')
      .assert.containsText('h1', 'Welcome to Your Vue.js App')
      .assert.elementCount('img', 1)
      .end()
  }
}

In your case this test is failing because you have probably removed the file named App.vue that is generated through vue-cli scaffolding. The error you get is because the above test checks, with a 5 seconds timeout, if a DOM node named "app" is rendered (i.e.: .waitForElementVisible('#app', 5000)).

Basically it is failing because you actually do not provide this div in your application anymore (due of App.vue removal, maybe).

So you have two options here:

• restoring the App.vue file (i.e.: create a div identified as 'app' where you mount a Vue instance);

• editing the end to end according to your needs.

Hope this helps!