react integrate jest

how to run jest in react with es6 syntax

Posted by boydfd on 2017-06-13 00:00:00 +0800

Recently by the same author:


领域驱动设计学习记录2

Entity

To integrate jest with react, I spend a lot of times.

So here, I write them done to make sure I can review it quick in the future.

I create a git repository, you can clone it, and switch to init branch. Then, follow the step one by one, I think you will familiar with jest soon.

Below, I will show you the README in my git repository:

install npm by nvm(if you don’t have node installed)

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.2/install.sh | bash

add below to .bash_profile or .zshrc

# if you use bash replace shellProfile with .bash_profile
shellProfile='.zshrc'
echo 'export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh" # This loads nvm' >> $shellProfile
source $shellProfile
nvm install 7.7.2

check your node and npm is already installed and install yarn

node -v
# v7.7.2
npm -v
# 4.1.2
npm install -g yarn

yarn -v
# yarn install v0.24.5

pull the init environment

git clone https://github.com/boydfd/jest.git
# if you have yarn
yarn

install all dependences add jest to project

yarn && yarn add --dev jest babel-jest react-test-renderer

add first test

  1. add jest configuration in package.json
// package.json

"jest": {
    "testMatch": [
      "<rootDir>/src/**/__tests__/**/*.js?(x)",
      "<rootDir>/src/**/?(*.)(spec|test).js?(x)"
    ]
  },
  1. add test file
// src/helloWorld.spec.js

it('first test', () => {
  expect(true, true)
})
  1. run yarn jest

add second test with es6 syntax

  1. add one more test in helloWorld.spec.js
// src/helloWorld.spec.js

import { arrowFunction } from './es6'

it('first test', () => {
  expect(true, true)
})

it('second test with es6 syntax', () => {
  expect('arrowFunction', arrowFunction())
})
  1. add es6.js file
// src/es6.js

export const arrowFunction = () => {
  return 'arrowFunction'
}
  1. run test and we will see error below:
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){import { arrowFunction } from './es6';
                                                                                             ^^^^^^
    SyntaxError: Unexpected token import

add es6 syntax support

  1. add babel es2015 (this package makes es6 syntax available)

yarn add --dev babel-preset-es2015

  1. add es2015 configuration in package.json
// package.json

"babel": {
    "presets": [
      "es2015",
      "react"
    ]
  },
  1. run test again and we can get test passed:
PASS src/helloWorld.spec.js
  ✓ first test (3ms)
  ✓ second test with es6 syntax (1ms)

Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        1.656s
Ran all test suites.
✨  Done in 2.88s.

add shared path alias (option)

  1. add shared: resolveApp('shared'), in paths.js
  2. add '@shared': paths.shared, in webpack.config.dev.js (attention: we should extract the duplication in webpack.config.dev.js and webpack.config.prod.js, but we don’t do this time)

make alias available in jest.

  1. create shared folder and add new component named HelloWorld:
// shared/components/HelloWorld/index.js

import React from 'react'

function HelloWorld() {
  return (
    <div>
      hello, world!
    </div>
  )
}

export default HelloWorld
  1. add third test which ues HelloWorld component inside @shared path:
// src/helloWorld.spec.js

import { arrowFunction } from './es6'
import React from 'react'
import HelloWorld from '@shared/components/HelloWorld/'
import renderer from 'react-test-renderer';

it('first test', () => {
  expect(true, true)
})

it('second test with es6 syntax', () => {
  expect('arrowFunction', arrowFunction())
})

it('third test with @shared alias', () => {
  const component = renderer.create(
    <HelloWorld />
  );
  let tree = component.toJSON();
  expect(tree).toMatchSnapshot();
})
  1. yarn jest and get failed:
 Cannot find module '@shared/components/HelloWorld/' from 'helloWorld.spec.js'
      
      at Resolver.resolveModule (node_modules/jest-resolve/build/index.js:179:17)
      at Object.<anonymous> (src/helloWorld.spec.js:4:19)

  1. make jest know this alias in jest configuration:
// package.json

"jest": {
    "testMatch": [
      "<rootDir>/src/**/__tests__/**/*.js?(x)",
      "<rootDir>/src/**/?(*.)(spec|test).js?(x)"
    ],
    "moduleNameMapper": {
      "^@shared(.*)\"?$": "<rootDir>/shared/$1"
    }
  },
  1. yarn jest and get passed:
 PASS  src/helloWorld.spec.js
  ✓ first test (3ms)
  ✓ second test with es6 syntax
  ✓ renders without crashing (10ms)

Snapshot Summary
 › 1 snapshot written in 1 test suite.

Test Suites: 1 passed, 1 total
Tests:       3 passed, 3 total
Snapshots:   1 added, 1 total
Time:        1.717s
Ran all test suites.
✨  Done in 2.76s.

add css support

  1. add className for our HelloWorld:
// shared/components/HelloWorld/index.js

import React from 'react'
import styles from './HelloWorld.css'
function HelloWorld() {
  return (
    <div className="helloWorld">
      hello, world!
    </div>
  )
}

export default HelloWorld
  1. add css ``` /* shared/components/HelloWorld/HelloWorld.css */

.helloWorld { background-color: red; }


3. yarn jest and failed:

({“Object.":function(module,exports,require,__dirname,__filename,global,jest){.helloWorld { ^ SyntaxError: Unexpected token .

  at ScriptTransformer._transformAndBuildScript (node_modules/jest-runtime/build/ScriptTransformer.js:289:17)
  at Object.<anonymous> (shared/components/HelloWorld/index.js:2:19)
  at Object.<anonymous> (src/helloWorld.spec.js:3:19)

4. enhance our jest configuration:

`yarn add --dev identity-obj-proxy`

// package.json

“jest”: { “testMatch”: [ “/src/**/__tests__/**/*.js?(x)", "/src/**/?(*.)(spec|test).js?(x)" ], "moduleNameMapper": { "^@shared(.*)\"?$": "/shared/$1", "\\.(css|scss)$": "identity-obj-proxy" } },


5. yarn jest and failed:

PASS src/helloWorld.spec.js ✓ first test (3ms) ✓ second test with es6 syntax (1ms) ✓ third test with @shared alias (9ms)

Snapshot Summary › 1 snapshot written in 1 test suite. › 1 obsolete snapshot found, run with yarn run jest -- -u to remove them.

Test Suites: 1 passed, 1 total Tests: 3 passed, 3 total Snapshots: 1 added, 1 total Time: 1.577s Ran all test suites. error Command failed with exit code 1.


6. check snapshot and make test pass:

`yarn run jest -- -u`

PASS src/helloWorld.spec.js ✓ first test (3ms) ✓ second test with es6 syntax (1ms) ✓ third test with @shared alias (10ms)

Snapshot Summary › 1 obsolete snapshot removed.

Test Suites: 1 passed, 1 total Tests: 3 passed, 3 total Snapshots: 1 passed, 1 total Time: 0.955s, estimated 1s Ran all test suites. ✨ Done in 1.87s.

```

Next?

test assert with Enzyme is comming soon.