Function name

tests/js/quint.js:17–20

(x, name)

    if (typeof x !== 'function') throw new Error(`'${x}' is not a function`);
  },
  name(x, name)
  {
    if (x.name !== name) throw new Error(`'${x}' does not have a name of ${name}`);
  },
  true(x)
  {
    if (x !== true) throw new Error(`'${x}' is not true`);