test/parallel/test-whatwg-encoding-singlebyte.mjs

// Test that single-byte encodings mappings are correct and match spec
// Works without Intl

// From: https://github.com/ExodusOSS/bytes/blob/master/tests/single-byte.test.js
// Copyright Exodus Movement. Licensed under MIT License.

import '../common/index.mjs';
import { readFileSync } from 'node:fs';
import { join } from 'node:path';
import { test, describe } from 'node:test';
import raw from '../fixtures/encoding/encodings.json' with { type: 'json' };

const groups = new Map(raw.map((x) => [x.heading, x.encodings.map((x) => x.name.toLowerCase())]));
const encodings = groups.get('Legacy single-byte encodings');

describe('single-byte encodings are supersets of ascii', () => {
  for (const encoding of encodings) {
    test(encoding, (t) => {
      const loose = new TextDecoder(encoding);
      const fatal = new TextDecoder(encoding, { fatal: true });
      for (let i = 0; i < 128; i++) {
        const str = String.fromCodePoint(i);
        t.assert.strictEqual(loose.decode(Uint8Array.of(i)), str, i);
        t.assert.strictEqual(fatal.decode(Uint8Array.of(i)), str, i);
      }
    });
  }
});

describe('single-byte encodings index', () => {
  for (const encoding of encodings) {
    test(encoding, (t) => {
      const loose = new TextDecoder(encoding);
      const fatal = new TextDecoder(encoding, { fatal: true });
      const file = encoding === 'iso-8859-8-i' ? `index-iso-8859-8.txt` : `index-${encoding}.txt`;
      const text = readFileSync(join(import.meta.dirname, '../fixtures/encoding/single-byte', file), 'utf8');
      const rows = text
        .split('\n')
        .map((x) => x.trim())
        .filter((x) => x && x[0] !== '#')
        .map((x) => x.split('\t'))
        .map(([istr, codeHex, description]) => {
          const i = Number(istr);
          t.assert.ok(i < 128);
          const code = parseInt(codeHex.slice(2), 16);
          t.assert.strictEqual(`${i}`, istr);
          t.assert.strictEqual('0x' + code.toString(16).padStart(4, '0').toUpperCase(), codeHex);
          t.assert.ok(code && code !== 0xff_fd && code <= 0xff_ff); // Can't be a replacement char, has to be <= 16-bit
          t.assert.ok(code < 0xd8_00 || code >= 0xe0_00); // not a surrogate
          return [i, { i, code, description }];
        });

      t.assert.ok(rows.length <= 128);
      const known = new Map(rows);
      t.assert.strictEqual(rows.length, known.size); // all unique

      for (let i = 0; i < 128; i++) {
        const row = known.get(i);
        const byte = i + 128;
        if (row) {
          t.assert.strictEqual(i, row.i);
          const str = String.fromCodePoint(row.code);
          t.assert.strictEqual(fatal.decode(Uint8Array.of(byte)), str, row.description);
          t.assert.strictEqual(loose.decode(Uint8Array.of(byte)), str, row.description);
        } else {
          t.assert.throws(() => fatal.decode(Uint8Array.of(byte)), TypeError);
          t.assert.strictEqual(loose.decode(Uint8Array.of(byte)), '\uFFFD');
        }
      }
    });
  }
});

// https://encoding.spec.whatwg.org/#x-user-defined-decoder
test('x-user-defined', (t) => {
  const encoding = 'x-user-defined';
  const loose = new TextDecoder(encoding);
  const fatal = new TextDecoder(encoding, { fatal: true });
  for (let byte = 0; byte < 256; byte++) {
    const str = String.fromCodePoint(byte >= 0x80 ? 0xF780 + byte - 0x80 : byte);
    t.assert.strictEqual(fatal.decode(Uint8Array.of(byte)), str, byte);
    t.assert.strictEqual(loose.decode(Uint8Array.of(byte)), str, byte);
  }
});