Issue 5175 - Reject element hiding filter with empty domain names

test/filterClasses.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
@@ skipping 453 matching lines @@
     filter.hitCount++;
   }, ["filter.hitCount", "foobar"], "Increasing filter hit counts");
   checkNotifications(() =>
   {
     filter.hitCount = 0;
   }, ["filter.hitCount", "foobar"], "Resetting filter hit counts");
 
   filter.delete();
   test.done();
 };
+
+exports.testEmptyElemHideDomains = function(test)
+{
+  let emptyDomainFilters = [
+    ",##selector", ",,,##selector", "~,foo.com##selector", "foo.com,##selector",
+    ",foo.com##selector", "foo.com,~##selector",
+    "foo.com,,bar.com##selector", "foo.com,~,bar.com##selector"
+  ];
+
+  for (let filterText of emptyDomainFilters)
+  {
+    let filter = Filter.fromText(filterText);
+    test.ok(filter instanceof InvalidFilter);
+    test.equal(filter.reason, "filter_invalid_domain");
+    filter.delete();
+  }
+
+  test.done();
+};