// instance for every unit test.
  MockWebServer server = new MockWebServer();

  // Schedule some responses.
  server.enqueue(new MockResponse().setBody("hello, world!"));
  server.enqueue(new MockResponse().setBody("sup, bra?"));
  server.enqueue(new MockResponse().setBody("yo dog"));

  // Start the server.
  server.start();

  // Ask the server for its URL. You'll need this to make HTTP requests.

---------------------

The above scenario is representative of most TLS set ups: the client uses certificates to validate
the identity of a server. The converse is also possible. Here we create a server that authenticates
a client and a client that authenticates a server.

```java
// Create the root for client and server to trust. We could also use different roots for each!
HeldCertificate rootCertificate = new HeldCertificate.Builder()