test-multiple-pmapskips-performance.js

import test from 'ava';
import timeSpan from 'time-span';
import assertInRange from './assert-in-range.js';
import pMap, {pMapSkip} from './index.js';

function generateSkipPerformanceData(length) {
	const data = [];
	for (let index = 0; index < length; index++) {
		data.push(pMapSkip);
	}

	return data;
}

test('multiple pMapSkips - algorithmic complexity', async t => {
	const testData = [generateSkipPerformanceData(1000), generateSkipPerformanceData(10_000), generateSkipPerformanceData(100_000)];
	const testDurationsMS = [];

	for (const data of testData) {
		const end = timeSpan();
		// eslint-disable-next-line no-await-in-loop
		await pMap(data, async value => value);
		testDurationsMS.push(end());
	}

	for (let index = 0; index < testDurationsMS.length - 1; index++) {
		// Time for 10x more items should take between 9x and 11x more time.
		const smallerDuration = testDurationsMS[index];
		const longerDuration = testDurationsMS[index + 1];

		// The longer test needs to be a little longer and also not 10x more than the
		// shorter test. This is not perfect... there is some fluctuation.
		// The idea here is to catch a regression that makes `pMapSkip` handling O(n^2)
		// on the number of `pMapSkip` items in the input.
		assertInRange(t, longerDuration, {start: 1.2 * smallerDuration, end: 15 * smallerDuration});
	}
});