@Test
public void the_guest_url_includes_the_environment_config() {

    mockStatic(System.class);
    final String expectedConfig = "HOST:PORT";
    when(System.getenv(GUEST_URI_ENV_PROPERTY_KEY)).thenReturn(expectedConfig);
    assertThat(new GuestFeedSubscriber().buildGuestUrl()).startsWith(format("http://%s/guest", expectedConfig));
}