Mocking builtins does not affect already-imported ESM namespace objects #62081
Description
Version
v24.14.0
Platform
Linux xxxxxxx 6.18.13-arch1-1 #1 SMP PREEMPT_DYNAMIC Wed, 25 Feb 2026 23:12:35 +0000 x86_64 GNU/Linux
Subsystem
No response
What steps will reproduce the bug?
Here is the reproduce code:
// timer-failed.test.mjs
import * as NodeTest from 'node:test';
import * as NodeTimers from 'node:timers/promises';
import * as NodeAssert from 'node:assert';
NodeTest.describe('Test suite for the package', async () => {
await NodeTest.it('should pass this test', async (ctx) => {
ctx.mock.timers.enable({ apis: ['Date', 'setTimeout'], now: 12345 });
const startTime = Date.now();
let t1 = 0;
await Promise.all([
(async () => {
await NodeTimers.setTimeout(1000, null);
t1 = Date.now();
})(),
(async () => {
ctx.mock.timers.runAll();
})()
]);
console.log(startTime);
console.log(t1);
NodeAssert.strictEqual(t1 - startTime, 1000);
});
});You can see the 2 console.log will print 12345\n12345, which is incorrect.
If you rewrite the file to CJS module, it works perfectly.
// timer.test.cjs
const NodeTest = require('node:test');
const NodeTimers = require('node:timers/promises');
const NodeAssert = require('node:assert');
NodeTest.describe('Test suite for the package', async () => {
await NodeTest.it('should pass this test', async (ctx) => {
ctx.mock.timers.enable({ apis: ['Date', 'setTimeout'], now: 12345 });
const startTime = Date.now();
let t1 = 0;
await Promise.all([
(async () => {
await NodeTimers.setTimeout(1000, null);
t1 = Date.now();
})(),
(async () => {
ctx.mock.timers.runAll();
})()
]);
console.log(startTime);
console.log(t1);
NodeAssert.strictEqual(t1 - startTime, 1000);
});
});Or just replace the timer code with await new Promise(resolve => setTimeout(resolve, 1000));, it also works well.
How often does it reproduce? Is there a required condition?
Everytime I run this code
What is the expected behavior? Why is that the expected behavior?
The code should print 12345\n13345, and pass the test.
In ESM, the node:timer/promises with ctx.mock.timers.runAll() should work as same as it does in CJS.
What do you see instead?
12345
12345
▶ Test suite for the package
✖ should pass this test (1002.976086ms)
✖ Test suite for the package (1004.29576ms)
Additional information
No response