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nodejs-github-bot merged 1 commit into from
Sep 15, 2026
+181 −113
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test: deflake util.throttle tests #66034

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170 changes: 170 additions & 0 deletions test/parallel/test-util-throttle-timing.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,170 @@
// Flags: --expose-internals
'use strict';

const common = require('../common');
const assert = require('node:assert');
const { mock } = require('node:test');
const { setImmediate } = require('node:timers/promises');
const { internalBinding } = require('internal/test/binding');

// Throttle uses the libuv clock as well as timers. Control both before loading
// the implementation, which captures setTimeout and clearTimeout.
mock.timers.enable({ apis: ['Date', 'setTimeout'] });
mock.method(internalBinding('timers'), 'getLibuvNow', () => Date.now());
const { throttle } = require('node:util');

process.on('unhandledRejection', common.mustNotCall());

(async () => {
{
const values = [];
const times = [];
const start = Date.now();
const throttled = throttle(common.mustCall(function(value) {
assert.strictEqual(this, throttled);
values.push(value);
times.push(Date.now() - start);
return value;
}, 5), 2, 40);

assert.strictEqual(typeof throttled.cancel, 'function');
assert.strictEqual(typeof throttled.hasImmediateCapacity, 'function');
assert.strictEqual(typeof throttled.ref, 'function');
assert.strictEqual(typeof throttled.unref, 'function');
assert.strictEqual(throttled.pending, null);
assert.strictEqual(throttled.pendingCount, 0);
assert.strictEqual(throttled.activeCount, 0);
assert.strictEqual(throttled.hasImmediateCapacity(), true);

const first = throttled(1);
const second = throttled(2);
const third = throttled(3);
const fourth = throttled(4);
const fifth = throttled(5);

assert(first instanceof Promise);
assert(second instanceof Promise);
assert.notStrictEqual(first, second);
assert.deepStrictEqual(values, [1, 2]);
assert.strictEqual(throttled.hasImmediateCapacity(), false);
assert.strictEqual(throttled.pending, fifth);
assert.strictEqual(throttled.pendingCount, 3);
assert.strictEqual(throttled.unref(), throttled);
assert.strictEqual(throttled.ref(), throttled);

mock.timers.tick(39);
assert.deepStrictEqual(values, [1, 2]);
mock.timers.tick(1);
assert.deepStrictEqual(values, [1, 2, 3, 4]);
assert.strictEqual(throttled.pendingCount, 1);
mock.timers.tick(39);
assert.deepStrictEqual(values, [1, 2, 3, 4]);
mock.timers.tick(1);

assert.deepStrictEqual(
await Promise.all([first, second, third, fourth, fifth]),
[1, 2, 3, 4, 5],
);
assert.deepStrictEqual(values, [1, 2, 3, 4, 5]);
assert.strictEqual(throttled.pending, null);
assert.strictEqual(throttled.pendingCount, 0);
assert.strictEqual(throttled.activeCount, 0);
assert.deepStrictEqual(times, [0, 0, 40, 40, 80]);
}

{
const values = [];
const throttled = throttle(common.mustCall((value) => {
values.push(value);
return value;
}, 2), 1, 20, { maxPending: 1 });
const first = throttled(1);
const second = throttled(2);
const dropped = throttled(3);

assert.deepStrictEqual(values, [1]);
assert.strictEqual(throttled.pendingCount, 1);
await setImmediate();
await assert.rejects(dropped, { code: 'ERR_THROTTLED' });
mock.timers.tick(19);
assert.deepStrictEqual(values, [1]);
mock.timers.tick(1);
assert.deepStrictEqual(await Promise.all([first, second]), [1, 2]);
assert.deepStrictEqual(values, [1, 2]);
}

{
const values = [];
const throttled = throttle(common.mustCall((value) => {
values.push(value);
return value;
}, 3), 2, 30, { overflow: 'drop' });
const first = throttled(1);
const second = throttled(2);
await assert.rejects(throttled(3), { code: 'ERR_THROTTLED' });
assert.deepStrictEqual(await Promise.all([first, second]), [1, 2]);

mock.timers.tick(29);
assert.strictEqual(throttled.hasImmediateCapacity(), false);
await assert.rejects(throttled(4), { code: 'ERR_THROTTLED' });
mock.timers.tick(1);
assert.strictEqual(throttled.hasImmediateCapacity(), true);
assert.strictEqual(await throttled(5), 5);
assert.deepStrictEqual(values, [1, 2, 5]);
}

// A rolling window releases one slot at a time when timers run on schedule.
// If dispatch is delayed until both slots expire, both calls may run together.
for (const delayed of [false, true]) {
const times = [];
const start = Date.now();
const throttled = throttle(common.mustCall((value) => {
times.push(Date.now() - start);
return value;
}, 4), 2, 80, { strict: true });

const first = throttled(1);
mock.timers.tick(40);
const second = throttled(2);
const third = throttled(3);
const fourth = throttled(4);

mock.timers.tick(39);
assert.deepStrictEqual(times, [0, 40]);
if (delayed) {
mock.timers.tick(41);
} else {
mock.timers.tick(1);
assert.deepStrictEqual(times, [0, 40, 80]);
mock.timers.tick(39);
assert.deepStrictEqual(times, [0, 40, 80]);
mock.timers.tick(1);
}

assert.deepStrictEqual(
await Promise.all([first, second, third, fourth]),
[1, 2, 3, 4],
);
assert.deepStrictEqual(times, delayed ? [0, 40, 120, 120] : [0, 40, 80, 120]);
}

{
let recursive;
const values = [];
const throttled = throttle(common.mustCall((value) => {
values.push(value);
if (value === 1) recursive = throttled(2);
return value;
}, 2), 1, 20);

const first = throttled(1);
assert.deepStrictEqual(values, [1]);
assert.strictEqual(throttled.pending, recursive);
assert.strictEqual(throttled.pendingCount, 1);
mock.timers.tick(19);
assert.deepStrictEqual(values, [1]);
mock.timers.tick(1);
assert.deepStrictEqual(await Promise.all([first, recursive]), [1, 2]);
assert.deepStrictEqual(values, [1, 2]);
}
})().then(common.mustCall()).finally(() => mock.reset());

@aduh95 aduh95 Sep 15, 2026

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Suggested change
})().then(common.mustCall()).finally(() => mock.reset());
})().finally(() => mock.reset()).then(common.mustCall());

124 changes: 11 additions & 113 deletions test/parallel/test-util-throttle.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@
const common = require('../common');
const assert = require('node:assert');
const { createHook } = require('node:async_hooks');
const { setImmediate, setTimeout } = require('node:timers/promises');
const { setImmediate } = require('node:timers/promises');
const { throttle } = require('node:util');
const { TIMEOUT_MAX } = require('internal/timers');

Expand Down Expand Up @@ -95,55 +95,9 @@ throttle(() => {}, 1, 1, {
);
}

// Keep windows open across synchronous assertions, even if the process is
// descheduled. Window expiration is covered in test-util-throttle-timing.js.
(async () => {
{
const values = [];
const times = [];
const start = Date.now();
const throttled = throttle(common.mustCall(function(value) {
assert.strictEqual(this, throttled);
values.push(value);
times.push(Date.now() - start);
return value;
}, 5), 2, 40);

assert.strictEqual(typeof throttled.cancel, 'function');
assert.strictEqual(typeof throttled.hasImmediateCapacity, 'function');
assert.strictEqual(typeof throttled.ref, 'function');
assert.strictEqual(typeof throttled.unref, 'function');
assert.strictEqual(throttled.pending, null);
assert.strictEqual(throttled.pendingCount, 0);
assert.strictEqual(throttled.activeCount, 0);
assert.strictEqual(throttled.hasImmediateCapacity(), true);

const first = throttled(1);
const second = throttled(2);
const third = throttled(3);
const fourth = throttled(4);
const fifth = throttled(5);

assert(first instanceof Promise);
assert(second instanceof Promise);
assert.notStrictEqual(first, second);
assert.deepStrictEqual(values, [1, 2]);
assert.strictEqual(throttled.hasImmediateCapacity(), false);
assert.strictEqual(throttled.pending, fifth);
assert.strictEqual(throttled.pendingCount, 3);
assert.strictEqual(throttled.unref(), throttled);
assert.strictEqual(throttled.ref(), throttled);

assert.deepStrictEqual(
await Promise.all([first, second, third, fourth, fifth]),
[1, 2, 3, 4, 5],
);
assert.deepStrictEqual(values, [1, 2, 3, 4, 5]);
assert.strictEqual(throttled.pending, null);
assert.strictEqual(throttled.pendingCount, 0);
assert.strictEqual(throttled.activeCount, 0);
assert(times[2] - times[0] >= 30);
assert(times[4] - times[2] >= 30);
}

{
let running = 0;
let maxRunning = 0;
Expand Down Expand Up @@ -220,24 +174,6 @@ throttle(() => {}, 1, 1, {
assert.strictEqual(throttled.activeCount, 0);
}

{
const values = [];
const throttled = throttle(common.mustCall((value) => {
values.push(value);
return value;
}, 2), 1, 20, { maxPending: 1 });
const first = throttled(1);
const second = throttled(2);
const dropped = throttled(3);

assert.deepStrictEqual(values, [1]);
assert.strictEqual(throttled.pendingCount, 1);
await setImmediate();
await assert.rejects(dropped, { code: 'ERR_THROTTLED' });
assert.deepStrictEqual(await Promise.all([first, second]), [1, 2]);
assert.deepStrictEqual(values, [1, 2]);
}

{
let timeoutCount = 0;
const hook = createHook({
Expand All @@ -249,7 +185,7 @@ throttle(() => {}, 1, 1, {
const throttled = throttle(common.mustCall((value) => {
values.push(value);
return value;
}, 3), 2, 30, { overflow: 'drop' });
}, 3), 2, TIMEOUT_MAX, { overflow: 'drop' });

hook.enable();
const first = throttled(1);
Expand All @@ -265,37 +201,14 @@ throttle(() => {}, 1, 1, {
await assert.rejects(dropped, { code: 'ERR_THROTTLED' });
assert.deepStrictEqual(await Promise.all([first, second]), [1, 2]);

await setTimeout(30);
throttled.cancel();
assert.strictEqual(await throttled(4), 4);
assert.deepStrictEqual(values, [1, 2, 4]);
}

{
const times = [];
const start = Date.now();
const throttled = throttle(common.mustCall((value) => {
times.push(Date.now() - start);
return value;
}, 4), 2, 80, { strict: true });

const first = throttled(1);
await setTimeout(40);
const second = throttled(2);
const third = throttled(3);
const fourth = throttled(4);

assert.deepStrictEqual(
await Promise.all([first, second, third, fourth]),
[1, 2, 3, 4],
);
assert(times[2] - times[0] >= 65);
assert(times[3] - times[1] >= 65);
assert(times[3] - times[2] >= 25);
}

{
const reason = new Error('cancelled');
const throttled = throttle(common.mustCall((value) => value, 2), 1, 100);
const throttled = throttle(common.mustCall((value) => value, 2), 1, TIMEOUT_MAX);
const first = throttled(1);
const second = throttled(2);
const third = throttled(3);
Expand All @@ -322,7 +235,7 @@ throttle(() => {}, 1, 1, {
{
const reason = new Error('stop');
const controller = new AbortController();
const throttled = throttle(common.mustCall((value) => value), 1, 100, {
const throttled = throttle(common.mustCall((value) => value), 1, TIMEOUT_MAX, {
signal: controller.signal,
});
const first = throttled(1);
Expand Down Expand Up @@ -363,23 +276,6 @@ throttle(() => {}, 1, 1, {
await assert.rejects(throttled(), (error) => error === expected);
}

{
let recursive;
const values = [];
const throttled = throttle(common.mustCall((value) => {
values.push(value);
if (value === 1) recursive = throttled(2);
return value;
}, 2), 1, 20);

const first = throttled(1);
assert.deepStrictEqual(values, [1]);
assert.strictEqual(throttled.pending, recursive);
assert.strictEqual(throttled.pendingCount, 1);
assert.deepStrictEqual(await Promise.all([first, recursive]), [1, 2]);
assert.deepStrictEqual(values, [1, 2]);
}

{
function original(first, second) {
return first + second;
Expand Down Expand Up @@ -409,7 +305,7 @@ throttle(() => {}, 1, 1, {
if (type === 'Timeout') timeoutCount++;
},
});
const throttled = throttle(common.mustCall((value) => value), 1, 100);
const throttled = throttle(common.mustCall((value) => value), 1, TIMEOUT_MAX);

hook.enable();
assert.strictEqual(throttled.hasImmediateCapacity(), true);
Expand All @@ -430,7 +326,7 @@ throttle(() => {}, 1, 1, {
if (type === 'Timeout') timeoutCount++;
},
});
const throttled = throttle(common.mustCall((value) => value), 1, 100);
const throttled = throttle(common.mustCall((value) => value), 1, TIMEOUT_MAX);
hook.enable();
const first = throttled(1);
const second = throttled(2);
Expand All @@ -440,6 +336,8 @@ throttle(() => {}, 1, 1, {
const thirdRejection = assert.rejects(third, { code: 'ABORT_ERR' });

assert.strictEqual(timeoutCount, 1);
assert.strictEqual(throttled.unref(), throttled);
assert.strictEqual(throttled.ref(), throttled);
throttled.cancel();
assert.strictEqual(await first, 1);
await Promise.all([secondRejection, thirdRejection]);
Expand Down
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