Testing requests with generator functions ES6 style
I was implementing an async retrier while refactoring some callback hell. And while testing it I realized that there’s a simple way to make your generators wait.
'use strict';
function wait(done) {
setTimeout(done, 1000);
}That’s it. Function above is perfectly yieldable and will suspend your generator.
So in practice your test would look like this.
'use strict';
function wait(time) {
return function wait(done) {
setTimeout(done, time);
};
}
describe('Retry', () => {
it('retries 3 failed att', function* times3() {
// tell mocha to wait longer
this.timeout(8000);
let total = 3;
function* req() {
while (true) {
// our awesome wait function
yield wait(1000);
if (total-- === 1) {
return 'done';
}
throw new Error('test');
}
}
const result = yield retry(req, { times: 4 });
assert.equal(result, 'done');
});
});I use co-mocha for generator tests, hence 1
function* times3
Wait function also works in Chrome console in case you want to check it out (don’t forget to use strict).