### 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:

    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) {

 *    created.
 *  * **[Network Count:][networkCount]** the number of those requests that required network use.
 *  * **[Hit Count:][hitCount]** the number of those requests whose responses were served by the
 *    cache.
 *
 * Sometimes a request will result in a conditional cache hit. If the cache contains a stale copy of
 * the response, the client will issue a conditional `GET`. The server will then send either

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.internal.connection

/**
 * Used when we were unsuccessful in the planning phase of a connection:
 *
 *  * A DNS lookup failed
 *  * The configuration is incapable of carrying the request, such as when the client is configured

/**
 * 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)

        code = 204,
        body = "I'm not even supposed to be here today.",
      ),
    )
    executeSynchronously("/")
      .assertFailure("HTTP 204 had non-zero Content-Length: 39")
  }

  @Test
  fun http205WithBodyDisallowed() {
    server.enqueue(
      MockResponse(
        code = 205,
        body = "I'm not even supposed to be here today.",
      ),
    )
    executeSynchronously("/")

   * 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>())