MockWebServerPlus implements TestRule { public String url(String path) { return mockWebServer.url(path).toString(); } MockWebServerPlus();  MockWebServerPlus(MockWebServer mockWebServer); @Override Statement apply(final Statement base, final Description description); List<MockResponse> enqueue(String... paths); MockResponse enqueue(SocketPolicy socketPolicy); void enqueue(MockResponse response); String url(String path); RecordedRequest takeRequest(); void setDispatcher(Dispatcher dispatcher); MockWebServer server();  }
@Test public void generateValidUrl() { assertThat(server.url("")).isNotNull(); }