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

test/browser/snippets.js

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  *
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  * it under the terms of the GNU General Public License version 3 as
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  * 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";
 
 const library = require("../../lib/content/snippets.js");
 const {timeout} = require("./_utils");
 
 // We need this stub for the injector.
 window.browser = {
   runtime: {
     getURL: () => ""
   }
 };
 
+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'`);
+}
+
+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'`);
+}
+
 async function runSnippet(test, snippetName, ...args)
 {
   let snippet = library[snippetName];
 
   test.ok(snippet);
 
   snippet(...args);
 
   // For snippets that run in the context of the document via a <script>
   // element (i.e. snippets that use makeInjector()), we need to wait for
@@ skipping 191 matching lines @@
 
   if (element && msg)
   {
     test.equals(element.textContent, "", "Result element should be empty");
     test.equals(msg.textContent, "ReferenceError",
                 "There should have been an error");
   }
 
   test.done();
 };
+
+exports.testHideIfContainsVisibleText = async function(test)
+{
+  document.body.innerHTML = `
+    <style type="text/css">
+      body {
+        margin: 0;
+        padding: 0;
+      }
+      .transparent {
+        opacity: 0;
+        position: absolute;
+        display: block;
+      }
+      .zerosize {
+        font-size: 0;
+      }
+      div {
+        display: block;
+      }
+      .a {
+        display: inline-block;
+        white-space: pre-wrap;
+      }
+      .disp_none {
+        display: none;
+      }
+      .vis_hid {
+        visibility: hidden;
+      }
+      .vis_collapse {
+        visibility: collapse;
+      }
+      .same_colour {
+        color: rgb(255,255,255);
+        background-color: rgb(255,255,255);
+      }
+      #label {
+        overflow-wrap: break-word;
+      }
+    </style>
+    <div id="parent">
+      <div id="middle">
+        <div id="middle1"><div id="inside" class="inside"></div></div>
+      </div>
+      <div id="sibling">
+        <div id="tohide">to hide \ud83d\ude42!</div>
+      </div>
+      <div id="sibling2">
+        <div id="sibling21"><div id="sibling211" class="inside">Ad*</div></div>
+      </div>
+      <div id="label"><div id="content"><div class="a transparent">Sp</div><div class="a">Sp</div><div class="a zerosize">S</div><div class="a transparent">on</div><div class="a">on</div><div class="a zerosize">S</div></div></div>
+      <div id="label2"><div class="a vis_hid">Visibility: hidden</div><div class="a">S</div><div class="a vis_collapse">Visibility: collapse</div><div class="a">p</div><div class="a disp_none">Display: none</div><div class="a">o</div><div class="a same_colour">Same colour</div><div class="a">n</div></div>
+      <article id="article"><div style="display: none"><a href="foo"><div>Spon</div></a>Visit us</div></article>
+      <article id="article2"><div><a href="foo"><div>Spon</div></a>By this</div></article>
+      <article id="article3"><div><a href="foo"><div>by Writer</div></a> about the Sponsorship.</div></article>
+    </div>`;

[a.giammarchi, 2019/04/26 13:33:58]

nit: I wonder if for test maintainability sake we should properly format/indent
HTML so it's easier to change/review on the fly eventual changes

[hub, 2019/04/27 17:32:05]

A '\n' in the markup generate a blank space in the DOM, which mean it will be
translated as a space in the `contentText`. I can possibly indent a little bit,
but really not all of it.

Done

+
+  await runSnippet(
+    test, "hide-if-contains-visible-text", "Spon", "#parent > div"
+  );
+
+  let element = document.getElementById("label");
+  expectHidden(test, element, "label");
+  element = document.getElementById("label2");
+  expectHidden(test, element, "label2");
+
+  element = document.getElementById("article");
+  expectVisible(test, element, "article");
+  element = document.getElementById("article2");
+  expectVisible(test, element, "article2");
+
+  await runSnippet(
+    test, "hide-if-contains-visible-text", "Spon", "#parent > article", "#parent > article a"
+  );
+
+  element = document.getElementById("article");
+  expectHidden(test, element, "article");
+  element = document.getElementById("article2");
+  expectHidden(test, element, "article2");
+  element = document.getElementById("article3");
+  expectVisible(test, element, "article3");
+
+  test.done();

[a.giammarchi, 2019/04/26 13:33:59]

Happy to discuss this offline/elsewhere though, I just wanted to point this
little weird thing out.

This test looks OK, and maybe this is for another ticket/discussion, but I don't
understand why we need both `async` function declaration and `test.done()` at
the end.

The `test.done()` thing is from pre promise era, while here we're writing
already a flow that can wait anything, if needed, via `async`.

Accordingly, wouldn't be normal to have every test awaited so that `test.done()`
can be triggered automatically and it's one less thing to think about when
writing asynchronous tests?

[hub, 2019/04/27 17:32:06]

This is because we still use nodeunit. There is issue #6820 to get rid of it
(and a patch that uses mocha in TDD instead).

The `async` here is needed only for the `await runSnippet()`

+};