Files
TREK/client/tests/unit/scripts/precompress.test.ts
T
John Jahn 04b1fb72bb perf(static): serve the hashed assets from Brotli copies written at build time
Every file under assets/ was compressed again on each download, at the low
level a request path can afford. They carry their content hash in the name
and never change, so the client build now writes a Brotli copy beside each
compressible one (postbuild, scripts/precompress.mjs) and production points
a browser that accepts Brotli at that copy before express.static serves it.

Measured on a production build of 5.1.2, fetching the 652 precached files
the way a service worker install does: 16.3 MB -> 13.9 MB on the wire and
about 1.0 s -> 0.2 s of server CPU per install. A client without Brotli, a
range request and a build without copies are served exactly as before.
2026-11-11 20:59:40 +00:00

62 lines
2.4 KiB
TypeScript

import { randomBytes } from 'node:crypto';
import { existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { brotliDecompressSync } from 'node:zlib';
import { afterEach, describe, expect, it } from 'vitest';
import { MIN_BYTES, precompress } from '../../../scripts/lib/precompress.mjs';
let dir: string;
afterEach(() => rmSync(dir, { recursive: true, force: true }));
function tree(files: Record<string, string | Buffer>) {
dir = mkdtempSync(join(tmpdir(), 'trek-precompress-'));
for (const [name, content] of Object.entries(files)) {
mkdirSync(join(dir, name, '..'), { recursive: true });
writeFileSync(join(dir, name), content);
}
return dir;
}
const script = 'export const answer = 42;\n'.repeat(200);
describe('precompress', () => {
it('writes a Brotli copy that unpacks to the file, and counts what it saved', () => {
const result = precompress(tree({ 'index-AbCd1234.js': script, 'nested/Map-AbCd1234.css': script }));
expect(brotliDecompressSync(readFileSync(join(dir, 'index-AbCd1234.js.br'))).toString()).toBe(script);
expect(existsSync(join(dir, 'nested/Map-AbCd1234.css.br'))).toBe(true);
expect(result.files).toBe(2);
expect(result.before).toBe(script.length * 2);
expect(result.after).toBeLessThan(result.before);
});
it('leaves compressed formats and files under the size floor alone', () => {
const result = precompress(
tree({
'font-AbCd1234.woff2': script,
'clip-AbCd1234.mp4': script,
'tiny-AbCd1234.js': 'x'.repeat(MIN_BYTES - 1),
})
);
expect(result.files).toBe(0);
expect(existsSync(join(dir, 'font-AbCd1234.woff2.br'))).toBe(false);
expect(existsSync(join(dir, 'clip-AbCd1234.mp4.br'))).toBe(false);
expect(existsSync(join(dir, 'tiny-AbCd1234.js.br'))).toBe(false);
});
it('writes no copy that would not be smaller than its file', () => {
// Random bytes have nothing for a compressor to find.
const result = precompress(tree({ 'noise-AbCd1234.json': randomBytes(4096) }));
expect(result.files).toBe(0);
expect(existsSync(join(dir, 'noise-AbCd1234.json.br'))).toBe(false);
});
it('does nothing for a build directory that is not there', () => {
dir = join(tmpdir(), 'trek-precompress-missing');
expect(precompress(dir)).toEqual({ files: 0, before: 0, after: 0 });
});
});