Function check

deps/v8/test/mjsunit/regexp-unicode-sets.js:83–112

(re, expectMatch, expectNoMatch = [], negationValid = true)

    {length: 127}, (v, i) => { return String.fromCharCode(i); });

function check(re, expectMatch, expectNoMatch = [], negationValid = true) {
  if (expectNoMatch === undefined) {
    const expectSet = new Set(expectMatch.map(val => {
      return (typeof val == 'number') ? String(val) : val; }));
    expectNoMatch = allAscii.filter(val => !expectSet.has(val));
  }
  for (const match of expectMatch) {
    assertTrue(re.test(match), `${re}.test(${match})`);
  }
  for (const noMatch of expectNoMatch) {
    assertFalse(re.test(noMatch), `${re}.test(${noMatch})`);
  }
  if (!negationValid) {
    // Negation of classes containing strings is an error.
    const negated = `[^${re.source}]`;
    assertThrows(() => { new RegExp(negated, `${re.flags}`); }, SyntaxError,
        `Invalid regular expression: /${negated}/${re.flags}: ` +
        `Negated character class may contain strings`);
  } else {
    // Nest the current RegExp in a negated class and check expectations are
    // inversed.
    const inverted = new RegExp(`[^${re.source}]`, re.flags);
    for (const match of expectMatch) {
      assertFalse(inverted.test(match), `${inverted}.test(${match})`);
    }
    for (const noMatch of expectNoMatch) {
      assertTrue(inverted.test(noMatch), `${inverted}.test(${noMatch})`);
    }
  }
}

// Union with nested class
check(