taskFaker.sleep(100.µs)
      log += "red:finishing@${taskFaker.nanoTime}"
    }
    assertThat(taskFaker.executeCallCount).isEqualTo(1)

    // Enqueueing the blue task doesn't start a thread because the red one is still starting.
    blueQueue.execute("blue task") {
      log += "blue:starting@${taskFaker.nanoTime}"
      taskFaker.sleep(100.µs)

    val request = Request(server.url("/"))
    val response1 = client.newCall(request).execute()
    assertThat(response1.body.string()).isEqualTo("a")

    // Give the thread pool a chance to evict.
    Thread.sleep(500)
    val response2 = client.newCall(request).execute()
    assertThat(response2.body.string()).isEqualTo("b")
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)

    assertThat(connection.isHealthy(System.nanoTime())).isTrue()

    // But if the ping doesn't arrive, the connection goes unhealthy.
    Thread.sleep(TimeUnit.NANOSECONDS.toMillis(Http2Connection.DEGRADED_PONG_TIMEOUT_NS.toLong()))
    assertThat(connection.isHealthy(System.nanoTime())).isFalse()

    // When a pong does arrive, the connection becomes healthy again.

23F4..23FA    ; valid                  ;      ; NV8    # 7.0  BLACK MEDIUM LEFT-POINTING TRIANGLE..BLACK CIRCLE FOR RECORD
23FB..23FE    ; valid                  ;      ; NV8    # 9.0  POWER SYMBOL..POWER SLEEP SYMBOL
23FF          ; valid                  ;      ; NV8    # 10.0 OBSERVER EYE SYMBOL
2400..2424    ; valid                  ;      ; NV8    # 1.1  SYMBOL FOR NULL..SYMBOL FOR NEWLINE