asyncawait/test/async.iterable.ts

async/await for node.js

import chai = require('chai');
import Promise = require('bluebird');
import async = require('../src/async/index');
import await = require('../src/await/index');
var expect = chai.expect;


describe('async.iterable(...)', () => {

    var foo = async.iterable ((yield_, count: number, accum?: any[]) => {
        if (count < 1 || count > 9) throw new Error('out of range');
        for (var i = 1; i <= count; ++i) {
            if (accum) accum.push(111 * i);
            yield_ (111 * i);
        }
        return 'done';
    });


    describe('returns a function', () => {

        it('which returns an async iterator with next() and forEach() methods', () => {
            var syncResult = foo();
            expect(syncResult).is.an('object');
            expect(syncResult.next).is.a('function');
            expect(syncResult.forEach).is.a('function');
        });
    });


    describe('provides an iterator whose next() method', () => {

        it('synchronously returns a promise', () => {
            var iter = foo(3);
            expect(iter.next()).instanceOf(Promise);
        });

        it('begins executing synchronously and completes asynchronously', done => {
            var arr = [], iter = foo(3, arr);
            (<Promise<any>> iter.next())
            .then(() => expect(arr).to.deep.equal([111, '***']))
            .then(() => done())
            .catch(done);
            expect(arr).to.deep.equal([111]);
            arr.push('***');
        });

        it("preserves the 'this' context of the call", async.cps (() => {
            var foo = { bar: async.iterable (function (yield_) { yield_ (this); return 'done'; }) }, baz = {x:7};
            var iter = foo.bar();
            expect(await (iter.next())).to.deep.equal({ done: false, value: foo });
            expect(await (iter.next())).to.deep.equal({ done: true });
            iter = foo.bar.call(baz);
            expect(await (iter.next())).to.deep.equal({ done: false, value: baz });
            expect(await (iter.next())).to.deep.equal({ done: true });
        }));

        it('eventually resolves with the definition\'s yielded value', async.cps (() => {
            var iter = foo(3);
            expect(await (iter.next())).to.deep.equal({ done: false, value: 111 });
            expect(await (iter.next())).to.deep.equal({ done: false, value: 222 });
            expect(await (iter.next())).to.deep.equal({ done: false, value: 333 });
            expect(await (iter.next())).to.deep.equal({ done: true });
        }));

        it('eventually rejects with the definition\'s thrown value', async.cps (() => {
            var err, iter = foo(20);
            expect(() => await (iter.next())).to.throw(Error, 'out of range');
        }));

        it('eventually rejects if the iteration is already finished', async.cps(() => {
            var err, iter = foo(1);
            expect(await (iter.next())).to.deep.equal({ done: false, value: 111 });
            expect(await (iter.next())).to.deep.equal({ done: true });
            expect(() => await (iter.next())).to.throw(Error);
        }));

        it('works with await', done => {
            var foo = async.iterable ((yield_) => { yield_ (await (Promise.delay(20).then(() => 'blah'))); });
            foo().next()
            .then(result => expect(result).to.deep.equal({ done:false, value:'blah' }))
            .then(() => done())
            .catch(done);
        });
    });


    describe('provides an iterator whose forEach() method', () => {

        function nullFunc() { }

        //it('expects a single callback as its argument', () => {
        //    expect(() => (<any> foo(3)).forEach()).to.throw(Error);
        //    expect(() => (<any> foo(3)).forEach(1)).to.throw(Error);
        //    expect(() => (<any> foo(3)).forEach(1, nullFunc)).to.throw(Error);
        //});

        it('synchronously returns a promise', () => {
            var iter = foo(3);
            expect(iter.forEach(nullFunc)).instanceOf(Promise);
        });

        it('begins executing synchronously and completes asynchronously', done => {
            var arr = [], iter = foo(3, arr);
            (<Promise<any>> iter.forEach(nullFunc))
            .then(() => expect(arr).to.deep.equal([111, '***', 222, 333]))
            .then(() => done())
            .catch(done);
            expect(arr).to.deep.equal([111]);
            arr.push('***');
        });

        it('iterates over all yielded values', async.cps(() => {
            var arr = [], iter = foo(4);
            await (iter.forEach(val => arr.push(val)));
            expect(arr).to.deep.equal([111, 222, 333, 444]);
        }));

        //it('eventually resolves with the definition\'s returned value', async.cps(() => {
        //    var arr = [], iter = foo(7, arr);
        //    var result = await (iter.forEach(nullFunc));
        //    expect(result).to.equal('done');
        //    expect(arr.length).to.equal(7);
        //}));

        it('eventually rejects with the definition\'s thrown value', async.cps(() => {
            var err, iter = foo(20);
            expect(() => await (iter.forEach(nullFunc))).to.throw(Error, 'out of range');
        }));

        it('eventually rejects if the iteration is already finished', async.cps(() => {
            var err, iter = foo(1);
            await (iter.forEach(nullFunc));
            expect (() => await (iter.forEach(nullFunc))).to.throw(Error);
        }));

        it('works with await', done => {
            var foo = async.iterable ((yield_) => { yield_ (await (Promise.delay(20).then(() => 'blah'))); }), arr = [];
            foo().forEach(val => arr.push(val))
            .then(result => expect(result).to.not.exist)
            .then(() => expect(arr).to.deep.equal(['blah']))
            .then(() => done())
            .catch(done);
        });
    });
});