then verify that requests were made as expected.

Because it exercises your full HTTP stack, you can be confident that you're
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

    //
    // HttpUrl is quite lenient with what characters it accepts. In particular, characters like '{'
    // and '"' are permitted but unlikely to occur in real-world URLs. Unfortunately we can't just
    // lock it down due to URL templating: "http://{env}.{dc}.example.com".
    UrlComponentEncodingTester.newInstance()
      .nonPrintableAscii(Encoding.FORBIDDEN)

   * This is like [toLowerCase] except that it does nothing if this contains any non-ASCII
   * characters. We want to avoid lower casing special chars like U+212A (Kelvin symbol) because
   * they can return ASCII characters that match real hostnames.
   */
  private fun String.asciiToLowercase(): String {
    return when {
      isAscii() -> lowercase(Locale.US) // This is an ASCII string.
      else -> this
    }
  }

import org.junit.jupiter.api.AfterEach
import org.junit.jupiter.api.Tag
import org.junit.jupiter.api.Test

/**
 * Integration test to confirm that [TaskRunner] works with a real backend. Business logic is all
 * exercised by [TaskRunnerTest].
 *
 * This test is doing real sleeping with tolerances of 250 ms. Hopefully that's enough for even the
 * busiest of CI servers.
 */
@Tag("Slowish")
class TaskRunnerRealBackendTest {

  palette:
    - media: "(prefers-color-scheme: light)"
      scheme: default
      primary: teal
      accent: blue
      toggle:
        icon: octicons/sun-24
        name: "Switch to Dark Mode"
    - media: "(prefers-color-scheme: dark)"
      scheme: slate
      primary: teal
      accent: blue
      toggle:
        icon: octicons/moon-24
        name: "Switch to Light Mode"
  features:

  fun networkInterceptorThrowsRuntimeExceptionSynchronous() {
    interceptorThrowsRuntimeExceptionSynchronous(true)
  }

  /**
   * When an interceptor throws an unexpected exception, synchronous callers can catch it and deal
   * with it.
   */
  private fun interceptorThrowsRuntimeExceptionSynchronous(network: Boolean) {
    addInterceptor(network) { chain: Interceptor.Chain? -> throw RuntimeException("boom!") }
    val request =

) : DelegatingSocketFactory(getDefault()) {
  private val hostMapping = mutableMapOf<InetAddress, InetSocketAddress>()

  /** Sets the [real] address for [requested].  */
  operator fun set(
    requested: InetAddress,
    real: InetSocketAddress,
  ) {
    hostMapping[requested] = real
  }

  override fun createSocket(): Socket {
    return object : Socket() {
      override fun connect(
        endpoint: SocketAddress?,

     * fit comfortably within a single ethernet packet (1500 bytes) even with framing overhead.
     *
     * For tests this must be big enough to realize real compression on test messages like
     * 'aaaaaaaaaa...'. Our tests check if compression was applied just by looking at the size if
     * the inbound buffer.
     */
    const val DEFAULT_MINIMUM_DEFLATE_SIZE = 1024L
  }

        )
        return
      }

      // This is a long-lived response. Cancel full-call timeouts.
      call?.timeout()?.cancel()

      // Replace the body with a stripped one so the callbacks can't see real data.
      val response = response.stripBody()

      val reader = ServerSentEventReader(body.source(), this)
      try {
        if (!canceled) {
          listener.onOpen(this, response)

import okhttp3.internal.http2.Http2.formatFlags
import okhttp3.internal.http2.Http2.frameLog
import okhttp3.internal.http2.Http2.frameLogWindowUpdate
import org.junit.jupiter.api.Test

class FrameLogTest {
  /** Real stream traffic applied to the log format.  */
  @Test
  fun exampleStream() {
    assertThat(frameLog(false, 0, 5, TYPE_SETTINGS, FLAG_NONE))
      .isEqualTo(">> 0x00000000     5 SETTINGS      ")