Issue 7450 - Implement hide-if-contains-visible-text snippet

test/browser/_utils.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 "use strict";
 
 function timeout(delay)
 {
   return new Promise(resolve =>
   {
     setTimeout(resolve, delay);
   });
 }
 
 exports.timeout = timeout;
+
+function expectHidden(test, element, id)
+{
+  let withId = "";
+  if (typeof id != "undefined")
+    withId = ` with ID '${id}'`;
+
+  test.equal(
+    window.getComputedStyle(element).display, "none",
+    `The element${withId}'s display property should be set to 'none'`);
+}
+
+exports.expectHidden = expectHidden;
+
+function expectVisible(test, element, id)
+{
+  let withId = "";
+  if (typeof id != "undefined")
+    withId = ` with ID '${id}'`;
+
+  test.notEqual(
+    window.getComputedStyle(element).display, "none",
+    `The element${withId}'s display property should not be set to 'none'`);
+}
+
+exports.expectVisible = expectVisible;