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refactor(polyfills-loader): migrate tests to node:test #3086

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5 changes: 2 additions & 3 deletions packages/polyfills-loader/package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -26,9 +26,8 @@
},
"scripts": {
"build": "tsc",
"test:node": "mocha \"test/**/*.test.{ts,js,mjs,cjs}\" --require ts-node/register --reporter dot",
"test:update-snapshots": "mocha \"test/**/*.test.{ts,js,mjs,cjs}\" --require ts-node/register --update-snapshots",

@bashmish bashmish Jun 9, 2026 •
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just checking: since we don't have mocha snapshots anymore, we just need to update them manually?
I think we use snapshots in just 3 packages now, so it's not much work to update them

I also migrated 2 packages recently to a new solution where everything is managed in JS, becuase I found it really hard to extends tests with new use-case with folder-based approach, and debugging was very slow, so might be good to look into refactoring remaining tests to same approach

@bennypowers bennypowers Jun 9, 2026

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node:test has --experimental-test-snapshots (landed in Node 22.3). It writes .snapshot files and supports assert.snapshot(). That's one option.

"test:watch": "mocha \"test/**/*.test.{ts,js,mjs,cjs}\" --require ts-node/register --watch --watch-files src,test"
"test:node": "node --experimental-strip-types --test --test-force-exit test/**/*.test.ts",
"test:watch": "node --experimental-strip-types --test --test-force-exit --watch test/**/*.test.ts"
},
"files": [
"*.d.ts",
Expand Down
45 changes: 23 additions & 22 deletions packages/polyfills-loader/test/createPolyfillsData.test.ts
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import path from 'path';
import { expect } from 'chai';

import { PolyfillsLoaderConfig, PolyfillFile } from '../src/types.js';
import { createPolyfillsData } from '../src/createPolyfillsData.js';
import { noModuleSupportTest, fileTypes } from '../src/utils.js';
import type { PolyfillsLoaderConfig, PolyfillFile } from '../dist/types.js';
import { createPolyfillsData } from '../dist/createPolyfillsData.js';
import { noModuleSupportTest, fileTypes } from '../dist/utils.js';

function cleanupPolyfill(polyfill: PolyfillFile) {
if (!polyfill) {
Expand Down Expand Up @@ -40,11 +41,11 @@ describe('polyfills', () => {

const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'core-js',
type: fileTypes.SCRIPT,
Expand Down Expand Up @@ -138,11 +139,11 @@ describe('polyfills', () => {
};
const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'fetch',
path: 'polyfills/fetch.js',
Expand All @@ -165,11 +166,11 @@ describe('polyfills', () => {

const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'webcomponents-shady-css-custom-style',
type: fileTypes.SCRIPT,
Expand Down Expand Up @@ -197,11 +198,11 @@ describe('polyfills', () => {

const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'systemjs',
type: fileTypes.SCRIPT,
Expand Down Expand Up @@ -232,11 +233,11 @@ describe('polyfills', () => {

const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'systemjs',
type: fileTypes.SCRIPT,
Expand All @@ -257,11 +258,11 @@ describe('polyfills', () => {

const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'systemjs',
type: fileTypes.SCRIPT,
Expand All @@ -277,12 +278,12 @@ describe('polyfills', () => {
name: 'polyfill-a',
test: "'foo' in window",
content: '',
path: path.resolve(__dirname, 'custom-polyfills/polyfill-a.js'),
path: path.resolve(import.meta.dirname, 'custom-polyfills/polyfill-a.js'),
},
{
name: 'polyfill-b',
content: '',
path: path.resolve(__dirname, 'custom-polyfills/polyfill-b.js'),
path: path.resolve(import.meta.dirname, 'custom-polyfills/polyfill-b.js'),
},
];

Expand All @@ -300,11 +301,11 @@ describe('polyfills', () => {

const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'core-js',
type: fileTypes.SCRIPT,
Expand Down Expand Up @@ -338,11 +339,11 @@ describe('polyfills', () => {

const polyfillFiles = await createPolyfillsData(config);
for (const p of polyfillFiles) {
expect(p.content).to.be.a('string', `Polyfill ${p.name} has no content`);
assert.equal(typeof p.content, 'string', `Polyfill ${p.name} has no content`);
cleanupPolyfill(p);
}

expect(polyfillFiles).to.eql([
assert.deepEqual(polyfillFiles, [
{
name: 'systemjs',
type: fileTypes.SCRIPT,
Expand Down
28 changes: 17 additions & 11 deletions packages/polyfills-loader/test/createPolyfillsLoader.test.ts
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
import { expect } from 'chai';
import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import fs from 'fs';
import path from 'path';
import { PolyfillsLoaderConfig } from '../src/types.js';
import { createPolyfillsLoader } from '../src/createPolyfillsLoader.js';
import { noModuleSupportTest, fileTypes } from '../src/utils.js';
import type { PolyfillsLoaderConfig } from '../dist/types.js';
import { createPolyfillsLoader } from '../dist/createPolyfillsLoader.js';
import { noModuleSupportTest, fileTypes } from '../dist/utils.js';

const updateSnapshots = process.argv.includes('--update-snapshots');

Expand All @@ -14,26 +15,31 @@ interface TestSnapshotArgs {
}

async function testSnapshot({ name, config, expectedFiles = [] }: TestSnapshotArgs) {
const snapshotPath = path.join(__dirname, 'snapshots', 'createPolyfillsLoader', `${name}.js`);
const snapshotPath = path.join(
import.meta.dirname,
'snapshots',
'createPolyfillsLoader',
`${name}.js`,
);
const loader = await createPolyfillsLoader(config);
if (!loader) {
throw new Error('No loader was generated');
}

expect(loader.polyfillFiles.map(f => f.path)).to.eql(expectedFiles);
assert.deepEqual(
loader.polyfillFiles.map(f => f.path),
expectedFiles,
);

if (updateSnapshots) {
fs.writeFileSync(snapshotPath, loader.code, 'utf-8');
} else {
const snapshot = fs.readFileSync(snapshotPath, 'utf-8');
expect(loader.code.trim()).to.equal(snapshot.trim());
assert.equal(loader.code.trim(), snapshot.trim());
}
}

describe('createPolyfillsLoader', function describe() {
// bootup of the first test can take a long time in CI to load all the polyfills
this.timeout(5000);

describe('createPolyfillsLoader', { timeout: 5000 }, () => {
it('generates a loader script with one module resource', async () => {
await testSnapshot({
name: 'module-resource',
Expand Down
18 changes: 12 additions & 6 deletions packages/polyfills-loader/test/injectPolyfillsLoader.test.ts
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
import { expect } from 'chai';
import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import path from 'path';
import fs from 'fs';
import { injectPolyfillsLoader } from '../src/injectPolyfillsLoader.js';
import { noModuleSupportTest, fileTypes } from '../src/utils.js';
import { PolyfillsLoaderConfig } from '../src/types.js';
import { injectPolyfillsLoader } from '../dist/injectPolyfillsLoader.js';
import { noModuleSupportTest, fileTypes } from '../dist/utils.js';
import type { PolyfillsLoaderConfig } from '../dist/types.js';

const updateSnapshots = process.argv.includes('--update-snapshots');

Expand All @@ -15,14 +16,19 @@ const defaultConfig = {
};

async function testSnapshot(name: string, htmlString: string, config: PolyfillsLoaderConfig) {
const snapshotPath = path.join(__dirname, 'snapshots', 'injectPolyfillsLoader', `${name}.html`);
const snapshotPath = path.join(
import.meta.dirname,
'snapshots',
'injectPolyfillsLoader',
`${name}.html`,
);
const result = await injectPolyfillsLoader(htmlString, config);

if (updateSnapshots) {
fs.writeFileSync(snapshotPath, result.htmlString, 'utf-8');
} else {
const snapshot = fs.readFileSync(snapshotPath, 'utf-8');
expect(result.htmlString.trim()).to.equal(snapshot.trim());
assert.equal(result.htmlString.trim(), snapshot.trim());
}
}

Expand Down
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