jest-performance

A Benchmark js integration for Jest js

Install

npm i -D jest-performance

or

yarn add -D jest-performance

example

const array = [];
for (let i = 0; i < 10; i++) {
  array.push(array.length);
}

it('reduce v3 vs for v2', async () => {
  await expect().benchmark({
    'reduce v3': () => {
      const sum = array.reduce((acc, x) => acc + x, 0);
    },
    'for v4': () => {
      let sum = 0;
      for (let i = 0, arrayLength = array.length; i < arrayLength; i++) {
        sum += array[i];
      }
    },
  });
});

will print:

Setup

Jest >v24

Add jest-performance to your Jest setupFilesAfterEnv configuration

"jest": {
  "setupFilesAfterEnv": ["jest-performance"]
}

Jest <v23

"jest": {
  "setupTestFrameworkScriptFile": "jest-performance"
}

If you are already using another test framework, then you should create a test setup file and require each of the frameworks you are using.

For example:

// ./testSetup.js
require('jest-performance');
require('any other test framework libraries you are using');

Then in your Jest config:

"jest": {
  "setupTestFrameworkScriptFile": "./testSetup.js"
}

Also, since benchmarks tests are going to be slow, I suggest having a dedicated Jest setup for it. Something like:

// jest.perf.config.js
const baseConfig = require('./jest.config.js')
module.exports = {
  ...baseConfig,
  'cacheDirectory': './node_modules/.jestCachePerf',
  'testMatch': ['**/?(*.)(spec|test?(s)).perf.js?(x)'],
  "setupFilesAfterEnv": ["jest-performance"],
}

And a dedicated script:

"scripts": {
  // ...
  "test:perf": "jest --config ./jest.perf.config.js"
}