code: @Test public void testExtensionFactory(){
    try {
      ExtensionFactory factory=ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getExtension("myfactory");
      Assert.assertTrue(factory instanceof ExtensionFactory);
      Assert.assertTrue(factory instanceof com.alibaba.dubbo.common.extension.ExtensionFactory);
      Assert.assertTrue(factory instanceof MyExtensionFactory);
      ExtensionFactory spring=ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getExtension("spring");
      Assert.assertTrue(spring instanceof ExtensionFactory);
      Assert.assertFalse(spring instanceof com.alibaba.dubbo.common.extension.ExtensionFactory);
    }
   catch (  IllegalArgumentException expected) {
      fail();
    }
  }
  