code: @Test public void test_urlHolder_getAdaptiveExtension_noExtension() throws Exception {
    Ext2 ext=ExtensionLoader.getExtensionLoader(Ext2.class).getAdaptiveExtension();
    URL url=new URL("p1","1.2.3.4",1010,"path1");
    UrlHolder holder=new UrlHolder();
    holder.setUrl(url);
    try {
      ext.echo(holder,"haha");
      fail();
    }
   catch (  IllegalStateException expected) {
      assertThat(expected.getMessage(),containsString("Fail to get extension("));
    }
    url=url.addParameter("ext2","XXX");
    holder.setUrl(url);
    try {
      ext.echo(holder,"haha");
      fail();
    }
   catch (  IllegalStateException expected) {
      assertThat(expected.getMessage(),containsString("No such extension"));
    }
  }
  