code: @Test public void testPrefixMatch(){
  {
      ElementPath p=new ElementPath("/a/b");
      ElementSelector ruleElementSelector=new ElementSelector("/x/*");
      assertEquals(0,ruleElementSelector.getPrefixMatchLength(p));
    }
  {
      ElementPath p=new ElementPath("/a");
      ElementSelector ruleElementSelector=new ElementSelector("/x/*");
      assertEquals(0,ruleElementSelector.getPrefixMatchLength(p));
    }
  {
      ElementPath p=new ElementPath("/a/b");
      ElementSelector ruleElementSelector=new ElementSelector("/a/*");
      assertEquals(1,ruleElementSelector.getPrefixMatchLength(p));
    }
  {
      ElementPath p=new ElementPath("/a/b");
      ElementSelector ruleElementSelector=new ElementSelector("/A/*");
      assertEquals(1,ruleElementSelector.getPrefixMatchLength(p));
    }
  {
      ElementPath p=new ElementPath("/A/b");
      ElementSelector ruleElementSelector=new ElementSelector("/a/*");
      assertEquals(1,ruleElementSelector.getPrefixMatchLength(p));
    }
  {
      ElementPath p=new ElementPath("/a/b");
      ElementSelector ruleElementSelector=new ElementSelector("/a/b/*");
      assertEquals(2,ruleElementSelector.getPrefixMatchLength(p));
    }
  {
      ElementPath p=new ElementPath("/a/b");
      ElementSelector ruleElementSelector=new ElementSelector("/*");
      assertEquals(0,ruleElementSelector.getPrefixMatchLength(p));
    }
  }
  