Function assertDeepEq

example/tests/gm_xhr_test.js:1947–1951

(a, b, msg)

    if (a !== b) throw new Error(msg ? `${msg}: expected ${b}, got ${a}` : `expected ${b}, got ${a}`);
  }
  function assertDeepEq(a, b, msg) {
    const aj = JSON.stringify(a);
    const bj = JSON.stringify(b);
    if (aj !== bj) throw new Error(msg ? `${msg}: expected ${bj}, got ${aj}` : `deep equal failed`);
  }
  function getHeader(headersStr, key) {
    const lines = (headersStr || "").split(/\r?\n/);
    const line = lines.find((l) => l.toLowerCase().startsWith(key.toLowerCase() + ":"));