' + 'Living Dex '.repeat(500) + '
'; function request(acceptEncoding?: string, method = 'GET') { return new Request('http://localhost/', { method, headers: acceptEncoding ? { 'accept-encoding': acceptEncoding } : {} }); } function page(body: BodyInit | null = html, init: ResponseInit = {}) { return new Response(body, { status: 200, headers: { 'content-type': 'text/html; charset=utf-8', 'content-length': '999' }, ...init }); } async function bytes(response: Response) { return Buffer.from(await response.arrayBuffer()); } describe('pickEncoding', () => { it.each([ ['gzip, deflate, br', 'br'], ['gzip', 'gzip'], ['br;q=0, gzip', 'gzip'], ['*', 'br'], ['identity', null], ['gzip;q=0', null] ])('%s -> %s', (header, expected) => { expect(pickEncoding(header)).toBe(expected); }); it('returns null when the client sends no Accept-Encoding', () => { expect(pickEncoding(null)).toBeNull(); }); }); describe('compressResponse', () => { it('brotli-compresses HTML and the body round-trips', async () => { const response = compressResponse(request('gzip, br'), page()); expect(response.headers.get('content-encoding')).toBe('br'); expect(response.headers.get('content-length')).toBeNull(); expect(response.headers.get('vary')).toMatch(/Accept-Encoding/); const body = await bytes(response); expect(body.length).toBeLessThan(html.length / 4); expect(brotliDecompressSync(body).toString()).toBe(html); }); it('falls back to gzip for JSON', async () => { const json = JSON.stringify({ rows: Array.from({ length: 200 }, (_, i) => ({ i })) }); const response = compressResponse( request('gzip'), new Response(json, { headers: { 'content-type': 'application/json' } }) ); expect(response.headers.get('content-encoding')).toBe('gzip'); expect(gunzipSync(await bytes(response)).toString()).toBe(json); }); it('keeps set-cookie headers and the status', async () => { const original = page(html, { status: 404 }); original.headers.append('set-cookie', 'a=1; Path=/'); original.headers.append('set-cookie', 'b=2; Path=/'); const response = compressResponse(request('br'), original); expect(response.status).toBe(404); expect(response.headers.getSetCookie()).toEqual(['a=1; Path=/', 'b=2; Path=/']); }); it('flushes each streamed chunk rather than buffering the whole body', async () => { let sendRest: () => void = () => {}; const stream = new ReadableStreamshell
')); sendRest = () => { controller.enqueue(new TextEncoder().encode('streamed data
')); controller.close(); }; } }); const response = compressResponse(request('gzip'), page(stream)); const reader = response.body!.getReader(); // The shell arrives while the stream is still open. const first = await reader.read(); expect(gunzipSync(Buffer.from(first.value!), { finishFlush: 2 }).toString()).toBe( 'shell
' ); sendRest(); const rest: Uint8Array[] = [Buffer.from(first.value!)]; for (let chunk = await reader.read(); !chunk.done; chunk = await reader.read()) { rest.push(chunk.value); } expect(gunzipSync(Buffer.concat(rest)).toString()).toBe('shell
streamed data
'); }); it('passes responses through inside a Netlify (Lambda) function', () => { // adapter-netlify reads text bodies with response.text(), which would corrupt compressed bytes. process.env.AWS_LAMBDA_FUNCTION_NAME = 'sveltekit-render'; try { const original = page(); expect(compressResponse(request('br'), original)).toBe(original); } finally { delete process.env.AWS_LAMBDA_FUNCTION_NAME; } }); it.each([ ['a client that accepts no encoding', request(), page()], ['a HEAD request', request('br', 'HEAD'), page(null)], ['an image', request('br'), new Response('png', { headers: { 'content-type': 'image/png' } })], ['a 304', request('br'), new Response(null, { status: 304 })], [ 'an already-encoded body', request('br'), new Response('x', { headers: { 'content-type': 'text/html', 'content-encoding': 'gzip' } }) ] ])('leaves %s uncompressed', async (_label, req, res) => { const response = compressResponse(req, res); expect(response.headers.get('content-encoding')).toBe(res.headers.get('content-encoding')); }); });