assertThat(source1.readUtf8(10)).isEqualTo("abcdefghij")
    assertThat(source1.exhausted()).isTrue()
    source1.close()
    assertThat(relay1.isClosed).isTrue()

    // Since relay1 is closed, new sources cannot be created.
    assertThat(relay1.newSource()).isNull()
    val relay2 = read(file)
    assertThat(relay2.metadata()).isEqualTo(metadata)
    val source2 = relay2.newSource()!!.buffer()

OkHttpClient uses a connection pool. Its job is to maintain a reference to all open connections. When an HTTP request is started, OkHttp will attempt to reuse an existing connection from the pool. If there are no existing connections, a new one is created and put into the connection pool. For HTTP/2, the connection can be reused immediately. For HTTP/1, the request must be completed before it can be reused.

Since HTTP requests frequently happen in parallel, connection pooling must be thread-safe....

This [sample factory](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEvents.java) creates a unique ID for each call and uses that ID to differentiate calls in log messages.

```java

package okhttp3

import javax.net.ssl.SSLSocket
import javax.net.ssl.SSLSocketFactory
import okhttp3.FallbackTestClientSocketFactory.Companion.TLS_FALLBACK_SCSV

/**
 * An SSLSocketFactory that delegates calls. Sockets created by the delegate are wrapped with ones
 * that will not accept the [TLS_FALLBACK_SCSV] cipher, thus bypassing server-side fallback
 * checks on platforms that support it. Unfortunately this wrapping will disable any

  private val moshiConverterFactory = MoshiConverterFactory.create(moshi)

  private val retrofit =
    Retrofit.Builder()
      .baseUrl(SslLabsService.BASE_URL)
      .addConverterFactory(moshiConverterFactory)
      .callFactory(callFactory)
      .build()

  private val api = retrofit.create(SslLabsService::class.java)

  suspend fun query(): List<Client> {

1. Script the mocks.
2. Run application code.
3. Verify that the expected requests were made.

Here's a complete example:

```java
public void test() throws Exception {
  // Create a MockWebServer. These are lean enough that you can create a new
  // instance for every unit test.
  MockWebServer server = new MockWebServer();

  // Schedule some responses.
  server.enqueue(new MockResponse().setBody("hello, world!"));

   * the event source has already been closed or canceled.
   */
  fun cancel()

  fun interface Factory {
    /**
     * Creates a new event source and immediately returns it. Creating an event source initiates an
     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be

      ).decodeHex()
    serverWriter.writeMessageFrame(OPCODE_BINARY, payload)
    assertData("8232")
    assertData(payload)
  }

  @Test fun serverMessageLengthShort() {
    // Create a payload which will overflow the normal payload byte size.
    val payload = Buffer()
    while (payload.completeSegmentByteCount() <= PAYLOAD_BYTE_MAX) {
      payload.writeByte('0'.code)
    }

  public void run() throws Exception {
    File file = new File("README.md");

    Request request = new Request.Builder()
        .url("https://api.github.com/markdown/raw")
        .post(RequestBody.create(file, MEDIA_TYPE_MARKDOWN))
        .build();

    try (Response response = client.newCall(request).execute()) {
      if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

import okhttp3.Response;
import okhttp3.mockwebserver.MockResponse;
import okhttp3.mockwebserver.MockWebServer;
import okhttp3.tls.HandshakeCertificates;
import okhttp3.tls.HeldCertificate;

/**
 * Create an HTTPS server with a self-signed certificate that OkHttp trusts.
 */
public class HttpsServer {
  public void run() throws Exception {
    HeldCertificate localhostCertificate = new HeldCertificate.Builder()