swc-angular

⚡️ Speed Up Angular Testing with SWC 🦀

• ⚡️ Speed Up Angular Testing with SWC 🦀
  • 👀 What is this?
  • 🤔 Context
  • 🥇 Benchmark Summary
  • 🎭 Setup with Jest
    • 1. Install
    • 2. Configure
    • 3. Add reflect-metadata
  • ⚡️Setup with Vitest
    • 1. Install
    • 2. Configure
    • 3. Add reflect-metadata
  • 🥇 Benchmark Data
    • 🔥 No Cache
    • ⚡️ With Cache
    • 🥱 Cold Start
    • Configurations
    • Source

👀 What is this?

This is a set of Angular presets that enable you to use SWC (Speedy Web Compiler) with Jest or Vitest.

Switching to SWC can speed up your tests by 2x to 12x.

🤔 Context

Surprisingly, in most cases, the bottleneck in Jest & Vitest tests is not the test execution time nor the Angular JIT (Just-In-Time) compiler but the TypeScript transformer.

This is where SWC (Speedy Web Compiler) comes in. SWC is a JavaScript/TypeScript compiler that aims to be extremely fast.

This package enables you to use SWC with Angular projects by setting the right configuration for SWC and using our Angular plugin for SWC @jscutlery/swc-angular-plugin

🥇 Benchmark Summary

This chart is based on the benchmark where all caches were disabled as in most cases we will still have to transform the code that we changed and which is affecting our tests. In addition to that, incremental build tools like Nx (or jest/vitest changedSince/changed options) will reduce the amount of transforms.

Cf. Detailed Benchmark Data

🎭 Setup with Jest

1. Install

Install this preset and its dependencies via npm:

npm install -D @jscutlery/swc-angular @jscutlery/swc-angular-plugin @swc/core @swc/jest
grep .swc .gitignore || echo .swc >> .gitignore

2. Configure

In your Jest configuration file (e.g., jest.config.ts), use the swcAngularJestTransformer function to transform .ts, .js, and .mjs files.

import { swcAngularJestTransformer } from '@jscutlery/swc-angular';

export default {
  // ...
  transform: {
    '^.+\\.(ts|mjs|js)$': swcAngularJestTransformer(),
    '^.+\\.(html)$': [
      'jest-preset-angular',
      {
        tsconfig: '<rootDir>/tsconfig.spec.json',
        stringifyContentPathRegex: '\\.(html|svg)$',
      },
    ],
  },
  transformIgnorePatterns: ['node_modules/(?!.*\\.mjs$)'],
  // ...
};

3. Add reflect-metadata

In order for constructor injection to work, you need to import reflect-metadata in the setup file which is probably located at src/test-setup.ts.

import 'reflect-metadata';

⚡️Setup with Vitest

1. Install

Install this preset and its dependencies via npm:

npm install -D @jscutlery/swc-angular @jscutlery/swc-angular-plugin @swc/core unplugin-swc
grep .swc .gitignore || echo .swc >> .gitignore

2. Configure

In your vite configuration file (e.g., vite.config.ts), use the unplugin-swc plugin with our preset: swcAngularVitePreset.

import { swcAngularUnpluginOptions } from '@jscutlery/swc-angular';
import swc from 'unplugin-swc';
import { defineConfig } from 'vite';

export default defineConfig({
  // ...
  plugins: [swc.vite(swcAngularUnpluginOptions())],
  // ...
});

3. Add reflect-metadata

In order for constructor injection to work, you need to import reflect-metadata in the setup file which is probably located at src/test-setup.ts.

import 'reflect-metadata';

🥇 Benchmark Data

🔥 No Cache

All caches are cleared before each benchmark run.

Configuration	Relative	Mean [s]	Min [s]	Max [s]
🥇vitest-swc-no-isolate	1.00	3.137 ± 0.061	3.042	3.227
🥈jest-swc	3.31 ± 0.15	10.393 ± 0.429	9.745	10.994
🥉angular-cli-karma	3.52 ± 0.53	11.041 ± 1.642	10.218	15.690
angular-cli-web-test-runner	5.46 ± 0.45	17.118 ± 1.362	16.473	20.911
jest	5.78 ± 0.25	18.132 ± 0.716	17.553	19.998
angular-cli-jest	8.61 ± 0.63	27.009 ± 1.902	24.938	30.450
vitest-swc	8.94 ± 0.21	28.038 ± 0.402	27.539	28.617
vitest	11.43 ± 0.32	35.872 ± 0.727	34.452	37.340
vitest-no-isolate	11.49 ± 0.25	36.061 ± 0.369	35.414	36.502

⚡️ With Cache

All tests are ran once to warm up the cache before running the benchmark.

Configuration	Relative	Mean [s]	Min [s]	Max [s]
🥇vitest-swc-no-isolate	1.00	3.092 ± 0.090	3.030	3.301
🥈angular-cli-karma	1.91 ± 0.07	5.901 ± 0.139	5.718	6.131
🥉jest-swc	2.93 ± 0.18	9.045 ± 0.494	8.513	10.065
jest	4.07 ± 0.25	12.581 ± 0.663	11.572	13.915
angular-cli-web-test-runner	5.96 ± 0.29	18.428 ± 0.711	17.497	19.262
angular-cli-jest	8.46 ± 1.04	26.170 ± 3.117	23.350	31.983
vitest-swc	9.28 ± 0.36	28.691 ± 0.728	27.977	30.488
vitest-no-isolate	11.74 ± 0.45	36.286 ± 0.880	35.107	38.018
vitest	12.18 ± 0.63	37.666 ± 1.625	35.563	41.503

• Note that, as of today, vitest doesn't cache transformed files.

🥱 Cold Start

Run a single test module just and try to measure the bootstrap time.

Configuration	Relative	Mean [s]	Min [s]	Max [s]
🥇vitest-swc-no-isolate	1.00	1.260 ± 0.024	1.241	1.314
🥈vitest-swc	1.00 ± 0.03	1.262 ± 0.026	1.225	1.305
🥉jest-swc	1.44 ± 0.15	1.812 ± 0.186	1.714	2.310
vitest-no-isolate	1.47 ± 0.05	1.846 ± 0.056	1.797	1.949
vitest	1.61 ± 0.16	2.030 ± 0.198	1.814	2.423
jest	1.69 ± 0.08	2.136 ± 0.094	2.017	2.356
angular-cli-jest	1.73 ± 0.39	2.186 ± 0.495	1.869	3.119
angular-cli-web-test-runner	2.06 ± 1.15	2.602 ± 1.451	2.080	6.730
angular-cli-karma	5.08 ± 1.30	6.400 ± 1.636	5.377	10.177

Configurations

	Configuration	Test Isolation*
angular-cli-karma	Angular CLI's Karma	false
angular-cli-jest	Angular CLI's Jest	true
angular-cli-web-test-runner	Angular CLI's @web/test-runner	true
jest	Jest	true
jest-swc	Jest + SWC	true
vitest	Vitest	true
vitest-no-isolate	Vitest + No Isolation	false
vitest-swc	Vitest + SWC	true
vitest-swc-no-isolate	Vitest + SWC + No Isolation	false

• Test Isolation: this tells whether each test module has its own testing environment or if each one is isolated. (i.e. globals like the DOM are shared, asynchronous code might bleed between tests, etc...)

Source

💻 try it yourself: https://github.com/yjaaidi/experiments/tree/angular-swc-benchmark or checkout the last benchmark results: https://github.com/yjaaidi/experiments/actions/workflows/benchmark.yml