val buffer = Buffer()
    body.writeTo(buffer)
    assertThat(buffer.readUtf8()).isEqualTo(expected)
  }

  @Test
  fun characterEncoding() {
    // Browsers convert '\u0000' to '%EF%BF%BD'.
    assertThat(formEncode(0)).isEqualTo("%00")
    assertThat(formEncode(1)).isEqualTo("%01")
    assertThat(formEncode(2)).isEqualTo("%02")
    assertThat(formEncode(3)).isEqualTo("%03")