pad.pub0.org/tests/backend/specs/promises.js

86 lines
2.6 KiB
JavaScript

function m(mod) { return __dirname + '/../../../src/' + mod; }
const assert = require('assert').strict;
const promises = require(m('node/utils/promises'));
describe('promises.timesLimit', async () => {
let wantIndex = 0;
const testPromises = [];
const makePromise = (index) => {
// Make sure index increases by one each time.
assert.equal(index, wantIndex++);
// Save the resolve callback (so the test can trigger resolution)
// and the promise itself (to wait for resolve to take effect).
const p = {};
const promise = new Promise((resolve) => {
p.resolve = resolve;
});
p.promise = promise;
testPromises.push(p);
return p.promise;
};
const total = 11;
const concurrency = 7;
const timesLimitPromise = promises.timesLimit(total, concurrency, makePromise);
it('honors concurrency', async () => {
assert.equal(wantIndex, concurrency);
});
it('creates another when one completes', async () => {
const {promise, resolve} = testPromises.shift();
resolve();
await promise;
assert.equal(wantIndex, concurrency + 1);
});
it('creates the expected total number of promises', async () => {
while (testPromises.length > 0) {
// Resolve them in random order to ensure that the resolution order doesn't matter.
const i = Math.floor(Math.random() * Math.floor(testPromises.length));
const {promise, resolve} = testPromises.splice(i, 1)[0];
resolve();
await promise;
}
assert.equal(wantIndex, total);
});
it('resolves', async () => {
await timesLimitPromise;
});
it('does not create too many promises if total < concurrency', async () => {
wantIndex = 0;
assert.equal(testPromises.length, 0);
const total = 7;
const concurrency = 11;
const timesLimitPromise = promises.timesLimit(total, concurrency, makePromise);
while (testPromises.length > 0) {
const {promise, resolve} = testPromises.pop();
resolve();
await promise;
}
await timesLimitPromise;
assert.equal(wantIndex, total);
});
it('accepts total === 0, concurrency > 0', async () => {
wantIndex = 0;
assert.equal(testPromises.length, 0);
await promises.timesLimit(0, concurrency, makePromise);
assert.equal(wantIndex, 0);
});
it('accepts total === 0, concurrency === 0', async () => {
wantIndex = 0;
assert.equal(testPromises.length, 0);
await promises.timesLimit(0, 0, makePromise);
assert.equal(wantIndex, 0);
});
it('rejects total > 0, concurrency === 0', async () => {
await assert.rejects(promises.timesLimit(total, 0, makePromise), RangeError);
});
});