.isEqualTo("response body")
      requestBody.close()
      assertThat(responseBody.readUtf8Line()).isNull()
    }
    body.awaitSuccess()
  }

  /**
   * Duplex calls that have follow-ups are weird. By the time we know there's a follow-up we've
   * already split off another thread to stream the request body. Because we permit at most one

    )
    val url = server.url("/a")
    assertThat(get(url).body.string()).isEqualTo("a")
    val i = cache.urls()
    assertThat(i.next()).isEqualTo(url.toString())
    i.remove()

    // Too many calls to remove().
    assertFailsWith<IllegalStateException> {
      i.remove()
    }
  }

  @Test
  fun elementEvictedBetweenHasNextAndNext() {
    // Put a response in the cache.

 * this class separates _allocations_ from _streams_. An allocation is created by a call, used for
 * one or more streams, and then released. An allocated connection won't be stolen by other calls
 * while a redirect or authorization challenge is being handled.
 *
 * When the maximum concurrent streams limit is reduced, some allocations will be rescinded.
 * Attempting to create new streams on these allocations will fail.

   */
  fun send(bytes: ByteString): Boolean

  /**
   * Attempts to initiate a graceful shutdown of this web socket. Any already-enqueued messages will
   * be transmitted before the close message is sent but subsequent calls to [send] will return
   * false and their messages will not be enqueued.
   *
   * This returns true if a graceful shutdown was initiated by this call. It returns false if