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.
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.

![Events Diagram](../assets/images/******@****.***)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java

/**
 * Runs MockWebServer for the duration of a single test method.
 *
 * Specifically while junit instances passes into test constructor
 * are typically shares amongst all tests, a fresh instance will be
 * received here. Use with @BeforeAll and @AfterAll, is not supported.
 *
 * There are 3 ids for instances
 * - The test instance default (passed into constructor)

      arrayOf(
        TlsVersion.TLS_1_2,
        TlsVersion.TLS_1_1,
        TlsVersion.TLS_1_0,
      )
    var socket = createSocketWithEnabledProtocols(*enabledSocketTlsVersions)

    // MODERN_TLS is used here.
    val attempt0 =
      routePlanner.planConnectToRoute(route)
        .planWithCurrentOrInitialConnectionSpec(connectionSpecs, socket)
    assertThat(attempt0.isTlsFallback).isFalse()

   * mutated by the call thread only. If is accessed by background connect threads.
   */
  private val tcpConnectsInFlight = CopyOnWriteArrayList<Plan>()

  /**
   * Results are posted here as they occur. The find job is done when either one plan completes
   * successfully or all plans fail.
   */
  private val connectResults = taskRunner.backend.decorate(LinkedBlockingDeque<ConnectResult>())

    bufferA.writeUtf8("Dodgson, we've got Dodgson here!\n")
    operatorA.write(36, bufferA, 33)
    operatorB.read(0, bufferB, 9)
    assertThat(bufferB.readUtf8()).isEqualTo("Dodgson!\n")
    operatorA.read(9, bufferA, 27)
    assertThat(bufferA.readUtf8()).isEqualTo("You shouldn't use my name.\n")
    operatorB.read(36, bufferB, 33)
    assertThat(bufferB.readUtf8()).isEqualTo("Dodgson, we've got Dodgson here!\n")
  }

  @Test

  @JvmField val name: ByteString,
  /** Value in UTF-8 encoding. */
  @JvmField val value: ByteString,
) {
  @JvmField val hpackSize = 32 + name.size + value.size

  // TODO: search for toLowerCase and consider moving logic here.
  constructor(name: String, value: String) : this(name.encodeUtf8(), value.encodeUtf8())

  constructor(name: ByteString, value: String) : this(name, value.encodeUtf8())

---

Good bug reports include a failing test! Writing a test helps you to isolate and describe the problem, and it helps us to fix it fast. Bug reports without a failing test or reproduction steps are likely to be closed.

Here’s an example test to get you started.

        if (testClass != null) {
          access.registerAsUsed(testClass)
          registerTest(access, testClass)
        }
      } catch (e: Exception) {
        // If you throw an exception here then native image building fails half way through
        // silently without rewriting the binary. So we report noisily, but keep going and prefer
        // running most tests still.
        e.printStackTrace()
      }
    }

### [Connections](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-connection/)

When you request a URL with OkHttp, here's what it does:

 1. It uses the URL and configured OkHttpClient to create an **address**. This address specifies how we'll connect to the webserver.