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swc-angular

README.md

⚡️ Speed Up Angular Testing with SWC 🦀

👀 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

Benchmark

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

🥱 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