### 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.
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.

**This release fixes a severe bug where OkHttp incorrectly detected and recovered from unhealthy
connections.** Stale or canceled connections were incorrectly attempted when they shouldn't have
been, leading to rare cases of infinite retries. Please upgrade to this release!

 *  Fix: don't return stale DNS entries in `DnsOverHttps`. We were caching DNS results indefinitely
    rather than the duration specified in the response's cache-control header.

  for (i in 0 until length) {
    val c = this[i]
    // The WHATWG Host parsing rules accepts some character codes which are invalid by
    // definition for OkHttp's host header checks (and the WHATWG Host syntax definition). Here
    // we rule out characters that would cause problems in host headers.
    if (c <= '\u001f' || c >= '\u007f') {
      return true
    }
    // Check for the characters mentioned in the WHATWG Host parsing spec:

![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

    var b = 0
    for (codePoint in input) {
      if (codePoint < INITIAL_N) {
        result.writeByte(codePoint)
        b++
      }
    }

    // Copy a delimiter if any basic code points were emitted.
    if (b > 0) result.writeByte('-'.code)

    var n = INITIAL_N
    var delta = 0
    var bias = INITIAL_BIAS
    var h = b
    while (h < input.size) {

  }

  @Test
  fun connectViaHttpProxyToHttpsUsingHttpsProxySystemProperty() {
    testConnectViaHttpProxyToHttps(ProxyConfig.HTTPS_PROXY_SYSTEM_PROPERTY)
  }

  /**
   * We were verifying the wrong hostname when connecting to an HTTPS site through a proxy.
   * http://b/3097277
   */
  private fun testConnectViaHttpProxyToHttps(proxyConfig: ProxyConfig) {

 *    default to their previous value.
 *
 * Every [edit] call must be matched by a call to [Editor.commit] or [Editor.abort]. Committing is
 * atomic: a read observes the full set of values as they were before or after the commit, but never
 * a mix of values.
 *
 * Clients call [get] to read a snapshot of an entry. The read will observe the value at the time

            challenge.charset,
          )
        return request.newBuilder()
          .header(credentialHeader, credential)
          .build()
      }
    }

    return null // No challenges were satisfied!
  }

  @Throws(IOException::class)
  private fun Proxy.connectToInetAddress(
    url: HttpUrl,
    dns: Dns,
  ): InetAddress {
    return when (type()) {

    at com.android.org.conscrypt.NativeCrypto.SSL_do_handshake(Native Method)
```

You can check a web server's configuration using [Qualys SSL Labs][qualys]. OkHttp's TLS
configuration history is [tracked here](../security/tls_configuration_history.md).

Applications expected to be installed on older Android devices should consider adopting the

  /**
   * Returns the effective top-level domain plus one (eTLD+1) by referencing the public suffix list.
   * Returns null if the domain is a public suffix or a private address.
   *
   * Here are some examples:
   *
   * ```java
   * assertEquals("google.com", getEffectiveTldPlusOne("google.com"));
   * assertEquals("google.com", getEffectiveTldPlusOne("www.google.com"));