testing everything. You can even copy & paste HTTP responses from your real web
server to create representative test cases. Or test that your code survives in
awkward-to-reproduce situations like 500 errors or slow-loading responses.


### Example

Use MockWebServer the same way that you use mocking frameworks like
[Mockito](https://github.com/mockito/mockito):

1. Script the mocks.
2. Run application code.

    assertThat(formatDuration(-2_500_000_000L)).isEqualTo(" -3 s ")
    assertThat(formatDuration(-2_499_999_999L)).isEqualTo(" -2 s ")
    assertThat(formatDuration(-1_500_000_000L)).isEqualTo(" -2 s ")
    assertThat(formatDuration(-1_499_999_999L)).isEqualTo(" -1 s ")
    assertThat(formatDuration(-1_000_000_000L)).isEqualTo(" -1 s ")
    assertThat(formatDuration(  -999_500_000L)).isEqualTo(" -1 s ")

    val future1 = executor.submit(sourceReader(relay.newSource()))
    val future2 = executor.submit(sourceReader(relay.newSource()))
    Thread.sleep(500)
    sink.writeUtf8("abcdefghij")
    Thread.sleep(500)
    sink.writeUtf8("klmnopqrst")
    sink.close()
    assertThat<ByteString>(future1.get())
      .isEqualTo("abcdefghijklmnopqrst".encodeUtf8())
    assertThat<ByteString>(future2.get())

      throw RuntimeException("boom!")
    }

    queue.schedule("task", TimeUnit.MILLISECONDS.toNanos(200)) {
      log.put("normal task running")
      return@schedule -1L
    }

    queue.idleLatch().await(500, TimeUnit.MILLISECONDS)

    assertThat(log.take()).isEqualTo("failing task running")
    assertThat(log.take()).isEqualTo("uncaught exception: java.lang.RuntimeException: boom!")

        .throttleBody((64 * 1024).toLong(), 125, TimeUnit.MILLISECONDS),
    ) // 500 Kbps
    server.start()
    val call =
      client.newCall(
        Request.Builder()
          .url(server.url("/"))
          .build(),
      )
    val response = call.execute()
    interruptLater(500)
    val responseBody = response.body.byteStream()
    val buffer = ByteArray(1024)

    client =
      client.newBuilder()
        .callTimeout(250, TimeUnit.MILLISECONDS)
        .build()
    server.enqueue(
      MockResponse.Builder()
        .bodyDelay(500, TimeUnit.MILLISECONDS)
        .setHeader("content-type", "text/event-stream")
        .body("data: hey\n\n")
        .build(),
    )
    val source = newEventSource()

fun formatDuration(ns: Long): String {
  val s =
    when {
      ns <= -999_500_000 -> "${(ns - 500_000_000) / 1_000_000_000} s "
      ns <= -999_500 -> "${(ns - 500_000) / 1_000_000} ms"
      ns <= 0 -> "${(ns - 500) / 1_000} µs"
      ns < 999_500 -> "${(ns + 500) / 1_000} µs"
      ns < 999_500_000 -> "${(ns + 500_000) / 1_000_000} ms"
      else -> "${(ns + 500_000_000) / 1_000_000_000} s "
    }
  return String.format("%6s", s)

        .url("http://httpbin.org/delay/1") // This URL is served with a 1 second delay.
        .build()

    // Copy to customize OkHttp for this request.
    val client1 =
      client.newBuilder()
        .readTimeout(500, TimeUnit.MILLISECONDS)
        .build()
    try {
      client1.newCall(request).execute().use { response ->
        println("Response 1 succeeded: $response")
      }
    } catch (e: IOException) {