assertThat(formEncode(255)).isEqualTo("%C3%BF")
  }

  @Throws(IOException::class)
  private fun formEncode(codePoint: Int): String {
    // Wrap the codepoint with regular printable characters to prevent trimming.
    val body =
      FormBody.Builder()
        .add("a", String(intArrayOf('b'.code, codePoint, 'c'.code), 0, 3))
        .build()
    val buffer = Buffer()
    body.writeTo(buffer)