function test(REGEX_RE, filter, mutation, expected) {
  if(Array.isArray(mutation)) {
    return mutation.forEach(m => test(REGEX_RE, filter, m, expected));
  }


  const exec = REGEX_RE.exec(filter);
  try {
    const reg = new RegExp(exec[1], exec[2])
    const success = reg.test(mutation) === expected ? `\x1b[32msuccess\x1b[0m` : `\x1b[31mfailed \x1b[0m`;
    console.log('\t', success, filter, reg, mutation, expected);
  } catch(e) {
    console.log('\t', `\x1b[31mfailed \x1b[0m`, filter, 'Could not compile', exec.slice(1));
  }
}

function testfor(REGEX_RE) {
  console.log(REGEX_RE);
  test(REGEX_RE, '/^cou.*/', [
    'coucou', 'couteau', 'couperet'
  ], true);

  test(REGEX_RE, '/^cou.*/', [
    'toto', 'piscou'
  ], false);

  test(REGEX_RE, '/^cou.*/i', [
    'CoucOu', 'cOuteau', 'cOuperet'
  ], true);

  test(REGEX_RE, '/^co\\/u.*/', [
    'co/ucou', 'co/uteau', 'co/uperet'
  ], true);

  test(REGEX_RE, '/^co\\/u.*/', [
    'coucou', 'couteau', 'couperet'
  ], false);

  test(REGEX_RE, '/^co\\/u.*/i', [
    'cO/ucou', 'cO/uteau', 'cO/uperet'
  ], true);

  test(REGEX_RE, '/^co\\/u|toto.*/', [
    'toto', 'totocoucou'
  ], true);

  test(REGEX_RE, '/^co/u|toto.*/', [
    'toto', 'totocoucou'
  ], false);
}

testfor(/^\/(.*?)\/(\w*)/); // Initial regexp, should fail in several cases
testfor(/^\/((?:(?:.*?)(?:\\\/)?)*?)\/(\w*)/); // works for all test cases