headersOf("header1", "valué1")
    }.also { expected ->
      assertThat(expected.message)
        .isEqualTo("Unexpected char 0xe9 at 4 in header1 value: valué1")
    }
  }

  @Test fun mapFactoryRejectsUnicodeInHeaderName() {
    assertFailsWith<IllegalArgumentException> {
      mapOf("héader1" to "value1").toHeaders()
    }.also { expected ->
      assertThat(expected.message)