assertThat(relay1.newSource()).isNull()
    val relay2 = read(file)
    assertThat(relay2.metadata()).isEqualTo(metadata)
    val source2 = relay2.newSource()!!.buffer()
    assertThat(source2.readUtf8(10)).isEqualTo("abcdefghij")
    assertThat(source2.exhausted()).isTrue()
    source2.close()
    assertThat(relay2.isClosed).isTrue()

    // Since relay2 is closed, new sources cannot be created.