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:

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)

   * 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>())

  private fun buildServerSslSocketFactory(): SSLSocketFactory {
    // The test uses JDK default SSL Context instead of the Platform provided one
    // as Conscrypt seems to have some differences, we only want to test client side here.
    return try {
      val keyManager =
        newKeyManager(
          null,
          serverCert,
          serverIntermediateCa.certificate,
        )
      val trustManager =

      if (npe.message == NPE_THROW_WITH_NULL) {
        throw IOException(npe)
      }
    }
  }

  /**
   * Does all the work to build an HTTPS connection over a proxy tunnel. The catch here is that a
   * proxy server can issue an auth challenge and then close the connection.
   *
   * @return the next plan to attempt, or null if no further attempt should be made either because

     */
    @Throws(IOException::class)
    constructor(rawSource: Source) {
      rawSource.use {
        val source = rawSource.buffer()
        val urlLine = source.readUtf8LineStrict()
        // Choice here is between failing with a correct RuntimeException
        // or mostly silently with an IOException
        url = urlLine.toHttpUrlOrNull() ?: throw IOException("Cache corruption for $urlLine").also {

        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("/")

 *
 * **Not all cipher suites are supported on all platforms.** As newer cipher suites are created (for
 * stronger privacy, better performance, etc.) they will be adopted by the platform and then exposed
 * here. Cipher suites that are not available on either Android (through API level 24) or Java
 * (through JDK 9) are omitted for brevity.
 *
 * See [Android SSLEngine][sslengine] which lists the cipher suites supported by Android.
 *