public void appendWorld_is_called() {
        assertThat(helloWorldService).isNotNull();
        assertThat(message).isNotNull();

        message = helloWorldService.appendWorld(message);
    }
This is referred in {@link TestAspect}
jgiven-spring-junit4/src/test/java/com/tngtech/jgiven/integration/spring/test/proxy/WhenTestStageWithAspect.java