Remove the query string from links to xeets (#303)

* Remove query string from xeet links

* Move formatter test suite next to formatter itself

* Write test suite for URL normalization

assets/chat/js/formatters.test.js → assets/chat/js/formatters/AmazonAssociatesTagInjector.test.js

@@ -1,4 +1,4 @@
-import { AmazonAssociatesTagInjector } from './formatters';
+import AmazonAssociatesTagInjector from './AmazonAssociatesTagInjector';
 
 const chatStub = {
   config: {

assets/chat/js/formatters/UrlFormatter.js

@@ -71,16 +71,31 @@ export default class UrlFormatter {
       const m = decodedUrl.match(self.linkregex);
       if (m) {
         const encodedUrl = self.encodeUrl(m[0]);
+        const normalizedUrl = this.normalizeUrl(encodedUrl);
         const maxUrlLength = 90;
-        let urlText = encodedUrl;
+        let urlText = normalizedUrl;
         if (urlText.length > maxUrlLength) {
           urlText = `${urlText.slice(0, 40)}...${urlText.slice(-40)}`;
         }
         const extra = self.encodeUrl(decodedUrl.substring(m[0].length));
-        const href = `${scheme ? '' : 'http://'}${encodedUrl}`;
+        const href = `${scheme ? '' : 'http://'}${normalizedUrl}`;
         return `<a target="_blank" class="externallink ${extraclass}" href="${href}" rel="nofollow">${urlText}</a>${extra}`;
       }
       return url;
     });
   }
+
+  /**
+   * @param {string} url
+   * @return {string} The normalized URL.
+   */
+  normalizeUrl(url) {
+    if (/(x|twitter)\.com\/\w{1,15}\/status\/\d{2,19}\?/i.test(url)) {
+      // Remove the query string from xeet URLs to protect users from clicking
+      // on a link to a xeet they've already seen.
+      return url.split('?')[0];
+    }
+
+    return url;
+  }
 }

assets/chat/js/formatters/UrlFormatter.test.js

@@ -0,0 +1,29 @@
+import UrlFormatter from './UrlFormatter';
+
+const urlFormatter = new UrlFormatter();
+
+describe('Normalizing URLs', () => {
+  test('Remove the query string from a tweet URL', () => {
+    expect(
+      urlFormatter.normalizeUrl('https://twitter.com/jack/status/20?lang=en')
+    ).toBe('https://twitter.com/jack/status/20');
+  });
+
+  test('Remove the query string from a xeet URL', () => {
+    expect(
+      urlFormatter.normalizeUrl('https://x.com/jack/status/20?lang=en')
+    ).toBe('https://x.com/jack/status/20');
+  });
+
+  test("Don't modify a URL to a tweet that doesn't contain a query string", () => {
+    expect(urlFormatter.normalizeUrl('https://x.com/jack/status/20')).toBe(
+      'https://x.com/jack/status/20'
+    );
+  });
+
+  test("Don't modify a URL that isn't Twitter or X", () => {
+    expect(
+      urlFormatter.normalizeUrl('https://www.twitch.tv/search?term=vtuber')
+    ).toBe('https://www.twitch.tv/search?term=vtuber');
+  });
+});