coerce to 0

GoogleChrome · Aug 2, 2024 · 7e38a51 · 7e38a51
1 parent 9e292fd
commit 7e38a51
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Showing 2 changed files with 8 additions and 7 deletions.
diff --git a/core/computed/tbt-impact-tasks.js b/core/computed/tbt-impact-tasks.js
@@ -87,9 +87,12 @@ class TBTImpactTasks {
 
       tbtImpactTasks.push({
         ...task,
-        tbtImpact,
-        selfTbtImpact,
-        selfBlockingTime,
+        // Floating point numbers are not perfectly precise, so the subtraction operations above
+        // can sometimes output negative numbers close to 0 here. To prevent potentially confusing
+        // output we should bump those values to 0.
+        tbtImpact: Math.max(tbtImpact, 0),
+        selfTbtImpact: Math.max(selfTbtImpact, 0),
+        selfBlockingTime: Math.max(selfBlockingTime, 0),
       });
     }
 

diff --git a/core/test/computed/tbt-impact-tasks-test.js b/core/test/computed/tbt-impact-tasks-test.js
@@ -248,8 +248,7 @@ describe('TBTImpactTasks', () => {
       };
 
       const tasks = await TBTImpactTasks.request(metricComputationData, context);
-      // Should be >= 0 but provide some wiggle room for double precision
-      expect(tasks.every(t => t.selfTbtImpact >= -0.00001)).toBeTruthy();
+      expect(tasks.every(t => t.selfTbtImpact >= 0)).toBeTruthy();
 
       const tasksImpactingTbt = tasks.filter(t => t.tbtImpact);
       expect(tasksImpactingTbt.length).toMatchInlineSnapshot(`7374`);
@@ -299,8 +298,7 @@ describe('TBTImpactTasks', () => {
 
       const tasks = await TBTImpactTasks.request(metricComputationData, context);
 
-      // Should be >= 0 but provide some wiggle room for double precision
-      expect(tasks.every(t => t.selfTbtImpact >= -0.00001)).toBeTruthy();
+      expect(tasks.every(t => t.selfTbtImpact >= 0)).toBeTruthy();
 
       const tasksImpactingTbt = tasks.filter(t => t.tbtImpact);
       expect(tasksImpactingTbt.length).toMatchInlineSnapshot(`1722`);