unit/backoff.test.js

/* eslint-env node, mocha */
import { expect } from "chai";
import { ConstantBackoff } from "../../src/backoff/constant";
import { ExponentialBackoff } from "../../src/backoff/exponential";
describe("backoff strategies", () => {
    describe("constant strategy", () => {
        it("appears to work", () => {
            let exp = new ConstantBackoff({
                delay: 500,
                jitter: 0.5,
            });
            function next() {
                const value = exp.getDelay();
                exp = exp.next();
                return value;
            }
            const checkSequence = () => {
                expect(next()).to.be.within(500 * (1 - 0.5), 500 * (1 + 0.5));
                expect(next()).to.be.within(500 * (1 - 0.5), 500 * (1 + 0.5));
                expect(next()).to.be.within(500 * (1 - 0.5), 500 * (1 + 0.5));
                expect(next()).to.be.within(500 * (1 - 0.5), 500 * (1 + 0.5));
                expect(next()).to.be.within(500 * (1 - 0.5), 500 * (1 + 0.5));
                expect(next()).to.be.within(500 * (1 - 0.5), 500 * (1 + 0.5));
            };
            checkSequence();
            exp = exp.reset();
            const dupe = exp.reset();
            checkSequence();
            exp = dupe;
            checkSequence();
        });
    });
    describe("exponential strategy", () => {
        it("appears to work", () => {
            let exp = new ExponentialBackoff({
                initial: 500,
                max: 5000,
                random: 1,
            });
            function next() {
                const value = exp.getDelay();
                exp = exp.next();
                return value;
            }
            const checkSequence = () => {
                expect(next()).to.equal(500);
                expect(next()).to.be.oneOf([500, 1000]);
                expect(next()).to.be.oneOf([1000, 2000]);
                expect(next()).to.be.oneOf([2000, 4000]);
                expect(next()).to.be.oneOf([4000, 5000]);
                expect(next()).to.equal(5000);
            };
            checkSequence();
            exp = exp.reset();
            const dupe = exp.reset();
            checkSequence();
            exp = dupe;
            checkSequence();
        });
    });
});