tor-browser

commit e2afb0c982dae5a77f6c7025a626bf57e0b68c3d
parent 5622001e5bf0f47823188963bfcd2b82e4d6cf4b
Author: Rolf Rando <rrando@mozilla.com>
Date:   Wed, 10 Dec 2025 18:55:23 +0000

Bug 2005108 - fix logic bug on randomization r=home-newtab-reviewers,nbarrett

Differential Revision: https://phabricator.services.mozilla.com/D275715

Diffstat:
M
browser/extensions/newtab/lib/NewTabContentPing.sys.mjs
 | 
3
++-
M
browser/extensions/newtab/lib/TelemetryFeed.sys.mjs
 | 
8
++++++--
M
browser/extensions/newtab/test/xpcshell/test_TelemetryFeed.js
 | 
39
+++++++++++++++++++++++++++++++++++++++

3 files changed, 47 insertions(+), 3 deletions(-)
diff --git a/browser/extensions/newtab/lib/NewTabContentPing.sys.mjs b/browser/extensions/newtab/lib/NewTabContentPing.sys.mjs
@@ -350,7 +350,8 @@ export class NewTabContentPing {
    * Returns true or false with a certain proability specified
    *
    * @param {number} prob Probability
-   * @returns {boolean} Random boolean result of probability prob
+   * @returns {boolean} Random boolean result of probability prob. A higher prob
+   *   increases the chance of true being returned.
    */
   static decideWithProbability(prob) {
     if (prob <= 0) {
diff --git a/browser/extensions/newtab/lib/TelemetryFeed.sys.mjs b/browser/extensions/newtab/lib/TelemetryFeed.sys.mjs
@@ -883,7 +883,7 @@ export class TelemetryFeed {
 
     const { p } =
       this._privateRandomContentTelemetryProbablityValues[cache_key];
-    if (!lazy.NewTabContentPing.decideWithProbability(p)) {
+    if (lazy.NewTabContentPing.decideWithProbability(p)) {
       return item;
     }
     const allRecs = this.getAllRecommendations(); // Number of recommendations has changed
@@ -905,7 +905,11 @@ export class TelemetryFeed {
     };
     // If we're replacing a non top stories item, then assign the appropriate
     // section to the item
-    if (resultItem.section !== TOP_STORIES_SECTION_NAME && randomItem.section) {
+    if (
+      resultItem.section &&
+      resultItem.section !== TOP_STORIES_SECTION_NAME &&
+      randomItem.section
+    ) {
       resultItem.section = randomItem.section;
       resultItem.section_position = randomItem.section_position;
     }
diff --git a/browser/extensions/newtab/test/xpcshell/test_TelemetryFeed.js b/browser/extensions/newtab/test/xpcshell/test_TelemetryFeed.js
@@ -17,6 +17,7 @@ ChromeUtils.defineESModuleGetters(this, {
   HomePage: "resource:///modules/HomePage.sys.mjs",
   JsonSchemaValidator:
     "resource://gre/modules/components-utils/JsonSchemaValidator.sys.mjs",
+  NewTabContentPing: "resource://newtab/lib/NewTabContentPing.sys.mjs",
   sinon: "resource://testing-common/Sinon.sys.mjs",
   TelemetryController: "resource://gre/modules/TelemetryController.sys.mjs",
   TelemetryFeed: "resource://newtab/lib/TelemetryFeed.sys.mjs",
@@ -2711,3 +2712,41 @@ add_task(async function test_handleBlockUrl_no_record_dismiss_on_no_session() {
 
   sandbox.restore();
 });
+
+add_task(function test_randomizeOrganicContentEvent() {
+  info(
+    "TelemetryFeed._randomizeOrganicContentEvent should return true or false" +
+      " based on the given probability"
+  );
+  let sandbox = sinon.createSandbox();
+  let instance = new TelemetryFeed();
+
+  const computeRec = id => ({
+    corpus_item_id: `item-${id}`,
+    topic: "a",
+    is_sponsored: false,
+    section_id: "section",
+    section_position: 3,
+  });
+  const allRecs = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10].map(computeRec);
+  sandbox.stub(instance, "getRecommendationCount").returns(allRecs.length);
+  sandbox.stub(instance, "getAllRecommendations").returns(allRecs);
+  instance._privateRandomContentTelemetryProbablityValues = { epsilon: 30 };
+  let decideStub = sandbox.stub(NewTabContentPing, "decideWithProbability");
+  decideStub.returns(true);
+  let result = instance.randomizeOrganicContentEvent(allRecs[0]);
+  Assert.equal(result, allRecs[0]);
+  Assert.ok(decideStub.calledOnce, "decideWithProbability was called once");
+  const [probUsed] = decideStub.firstCall.args;
+  Assert.greater(probUsed, 0.9); // Epsilon 30 is very high probability
+  Assert.less(probUsed, 1.01);
+
+  // Run again - randomization kicks in
+  decideStub.returns(false);
+  sandbox.stub(NewTabContentPing, "secureRandIntInRange").returns(3);
+  result = instance.randomizeOrganicContentEvent(allRecs[0]);
+  Assert.equal(probUsed, decideStub.lastCall.args[0]);
+  Assert.deepEqual(result, allRecs[3]);
+
+  sandbox.restore();
+});