sync/test/util/token-bucket.js

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2017-08-02 02:29:11 +00:00
const assert = require('assert');
const TokenBucket = require('../../lib/util/token-bucket').TokenBucket;
describe('TokenBucket', () => {
describe('#throttle', () => {
let bucket;
beforeEach(() => {
bucket = new TokenBucket(5, 5);
});
it('consumes capacity and then throttles', () => {
assert(!bucket.throttle(), 'should not be empty yet');
assert(!bucket.throttle(), 'should not be empty yet');
assert(!bucket.throttle(), 'should not be empty yet');
assert(!bucket.throttle(), 'should not be empty yet');
assert(!bucket.throttle(), 'should not be empty yet');
assert(bucket.throttle(), 'should be empty now');
});
it('refills tokens', () => {
bucket.count = 0;
const oldRefill = bucket.lastRefill = Date.now() - 1000;
assert(!bucket.throttle(), 'should have refilled');
assert(bucket.lastRefill >= oldRefill + 1000, 'should have updated lastRefill');
});
it('refills at most {capacity} tokens', () => {
bucket.count = 0;
bucket.lastRefill = Date.now() - 10000;
bucket.throttle();
assert.strictEqual(bucket.count, 4);
});
it('does a partial refill', () => {
bucket.count = 0;
bucket.lastRefill = Date.now() - 400;
bucket.throttle();
assert.strictEqual(bucket.count, 1);
});
it('skips refilling if delta = 0', () => {
bucket.count = 0;
const oldRefill = bucket.lastRefill;
bucket.throttle();
assert.strictEqual(bucket.count, 0);
assert.strictEqual(bucket.lastRefill, oldRefill);
});
it('handles fractional refill rates', () => {
bucket = new TokenBucket(5, 0.1);
bucket.count = 0;
assert(bucket.throttle());
bucket.lastRefill = Date.now() - 10000;
assert(!bucket.throttle());
assert.strictEqual(bucket.count, 0);
});
it('handles infinite refill rate and capacity', () => {
bucket = new TokenBucket(Infinity, Infinity);
for (let i = 0; i < 100; i++) {
assert(!bucket.throttle(), 'should not throttle');
}
});
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});
});