Method set

src/test-utils.ts:215–217

(key: string, value: string)

    return super.has(key.toLowerCase())
  }
  set(key: string, value: string) {
    return super.set(key.toLowerCase(), value)
  }
  append(key: string, val: string) {
    let prev = this.get(key) || ''
    if (prev) prev += ', '