Testing

Extensions are essentially Node.js projects with some extra bits; meaning that the extensions can be tested in the same way.

You are free to use any testing framework and any testing methodology you wish.

We usually use Chai, Mocha, Nyc, and Sinon.

DevNote provide some more examples for other frameworks?

An example setup

The file structure (yes, yes; the sources are below):

/ .gitignore
/ .eslintrc.js
/ .mocharc.js
/ package.json

/ server-scripts
    / Sample.js
    / Sample.test.js
    / ...
/ client-scripts
    / ....

gitignore:

.vscode
node_modules
.nyc_output
coverage
yarn-error.log

eslintrc.js:

module.exports = {
  root: false,
  env: {
    node: true,
    es6: true,
  },
  extends: [
    'standard',
  ],
}

mocharc.js:

module.exports = {
  require: [
    'esm',
  ],
  'full-trace': true,
  bail: true,
  recursive: true,
  extension: ['.test.js'],
  spec: [
    'client-scripts/**/*.test.js',
    'server-scripts/**/*.test.js',
  ],
  'watch-files': [ 'src/**' ],
}

package.json:

{
  "scripts": {
    "lint": "eslint {server-scripts,client-scripts}/**/* --ignore-pattern *.test.js",
    "test:unit": "mocha",
    "test:unit:cc": "nyc mocha"
  },
  "devDependencies": {
    "chai": "^4.2.0",
    "eslint": "^6.8.0",
    "eslint-config-standard": "^14.1.0",
    "eslint-plugin-import": "^2.18.2",
    "eslint-plugin-node": "^10.0.0",
    "eslint-plugin-promise": "^4.2.1",
    "eslint-plugin-standard": "^4.0.1",
    "esm": "^3.2.25",
    "mocha": "^7.0.1",
    "nyc": "^14.1.1",
    "sinon": "^8.1.1"
  },
  "nyc": {
    "all": true,
    "reporter": [
      "lcov",
      "text"
    ],
    "include": [
      "client-scripts/**/*.js",
      "server-scripts/**/*.js"
    ],
    "exclude": [
      "**/*.test.js"
    ],
    "check-coverage": true,
    "per-file": true,
    "branches": 0,
    "lines": 0,
    "functions": 0,
    "statements": 0
  }
}

Sample.js

export default {
  /* istanbul ignore next */
  trigger ({ before }) {
    return before('create')
  },

  exec () {
    return 'Hello World!'
  }
}

Note this part:

// vv this line here vv
/* istanbul ignore next */
trigger ({ before }) {
  return before('create')
},

istanbul ignore next excludes the next function from the coverage report.

Sample.test.js

import { expect } from 'chai'
import Sample from './Sample'

describe(__filename, () => {
  describe('Sample exec result', () => {
    it('should return a string', () => {
      expect(Sample.exec()).to.eq("HelloWorld")
    })
  })
})

The above package.json defines three scripts:

lint: lint the code using the default ES6 standard (can be configured; see here),
test:unit: unit test the code with your .test.js files (can be configured in the .mocharc.js file),
test:unit:cc: unit test the code and return a code coverage report.

The code coverage report gets generated into the coverage directory.

Inspect the coverage/lcov-report directory for a HTML report.

I usually use the http-server package to help with this, but a simple "Open in <browser name here>" will do.

http-server coverage/lcov-report

DevNote: provide some complex examples using Sinon and promises.