### EventListener.Factory

In the preceding example we used a field, `callStartNanos`, to track the elapsed time of each event. This is handy, but it won’t work if multiple calls are executing concurrently. To accommodate this, use a `Factory` to create a new `EventListener` instance for each `Call`. This allows each listener to keep call-specific state.

    address[b++] = (value.ushr(8) and 0xff).toByte()
    address[b++] = (value and 0xff).toByte()
  }

  // All done. If compression happened, we need to move bytes to the right place in the
  // address. Here's a sample:
  //
  //      input: "1111:2222:3333::7777:8888"
  //     before: { 11, 11, 22, 22, 33, 33, 00, 00, 77, 77, 88, 88, 00, 00, 00, 00  }
  //   compress: 6
  //          b: 10

 * it easy to get sample values to use in such tests.
 *
 * This class is pretty fast and loose with default values: it attempts to provide values that are
 * well-formed, but doesn't guarantee values are internally consistent. Callers must take care to
 * configure the factory when sample values impact the correctness of the test.
 */
class TestValueFactory : Closeable {

    bytesIn.writeUtf8("www.example.com")
  }

  private fun checkReadFirstRequestWithoutHuffman() {
    assertThat(hpackReader!!.headerCount).isEqualTo(1)

    // [  1] (s =  57) :authority: www.example.com
    val entry = hpackReader!!.dynamicTable[readerHeaderTableLength() - 1]!!
    checkEntry(entry, ":authority", "www.example.com", 57)

    // Table size: 57

      private InputStream trustedCertificatesInputStream() {
        ... // Full source omitted. See sample.
      }

      public SSLContext sslContextForTrustedCertificates(InputStream in) {
        ... // Full source omitted. See sample.
      }
    ```

 [CustomTrustJava]: https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/CustomTrust.java

    private development environments that only carry test data. Prefer this over creating an
    all-trusting `TrustManager` because only hosts on the allowlist are insecure. From
    [our DevServer sample][dev_server]:

    ```kotlin
    val clientCertificates = HandshakeCertificates.Builder()
        .addPlatformTrustedCertificates()
        .addInsecureHost("localhost")
        .build()

      builder.addHeader("", "Value")
    }
  }

  @Test
  fun headerAllowsTabOnlyInValues() {
    val builder = Request.Builder()
    builder.header("key", "sample\tvalue")
    assertFailsWith<IllegalArgumentException> {
      builder.header("sample\tkey", "value")
    }
  }

  @Test
  fun headerForbidsControlCharacters() {
    assertForbiddenHeader("\u0000")
    assertForbiddenHeader("\r")

plugins {
  kotlin("jvm")
  application
}

application {
  mainClass.set("okhttp3.sample.Crawler")
}

dependencies {
  implementation(projects.okhttp)
  implementation(libs.jsoup)
}

tasks.compileJava {
  options.isWarnings = false

       *
       * Example:
       * ```
       * --> POST /greeting http/1.1 (3-byte body)
       *
       * <-- 200 OK (22ms, 6-byte body)
       * ```
       */
      BASIC,

      /**
       * Logs request and response lines and their respective headers.
       *
       * Example:
       * ```
       * --> POST /greeting http/1.1
       * Host: example.com
       * Content-Type: plain/text

awkward-to-reproduce situations like 500 errors or slow-loading responses.


### 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 {