TST: bind to events only once for testing

src/jquery.urlfilter.js

 import {parse} from './url.js'
-import {hasdata} from './jquery.util.js'
+import {hasdata} from './_util.js'
 
 export function urlfilter(options) {
   options = options || {}

test/jquery.urlfilter.html

@@ -137,15 +137,15 @@
         $('.selector-div, .selector-iframe').each(function() {
           var $this = $(this)
           var $target = $($this.data('target'))
-            .on('load', function(e) {
+            .one('load', function(e) {
               t.equal(e.type, 'load', 'load event')
               t.equal($target.attr('src'), 'empty.html?y=1&x=1')
-              t.ok(e.url)
+              t.ok(e.url, 'load event url exists')
             })
           $this
-            .on('urlfilter', function (e) {
+            .one('urlfilter', function (e) {
               t.equal(e.type, 'urlfilter', 'urlfilter event')
-              t.ok(e.url)
+              t.ok(e.url, 'urlfilter event url exists')
             })
             .dispatch('click')
         })