select.js
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/* jshint loopfunc:true */
/* global describe:true, beforeEach:true, afterEach:true, it:true */
var chan = require('..')
var expect = require('expect.js')
describe('Channel select', function () {
var random
beforeEach(function (done) {
// save Math.random
random = Math.random
done()
})
afterEach(function (done) {
// restore Math.random
Math.random = random
done()
})
it(
'should be able to select on channels',
function (done) {
var ch1 = chan()
var ch2 = chan()
chan.select(ch1, ch2)(function (err, ch) {
expect(ch).to.equal(ch2)
ch2.selected(function (err, val) {
expect(val).to.equal(42)
done()
})
})
ch2(42)
}
)
it(
'should be able to select on multiple channels',
function (done) {
var chs = [chan(), chan()]
var remaining = chs.length
chs.forEach(function (needle, i) {
chan.select.apply(null, chs)(function (err, ch) {
expect(ch).to.equal(needle)
ch.selected(function (err, val) {
expect(val).to.equal(i*10)
if (--remaining === 0) {
done()
}
})
})
})
chs.forEach(function (ch, i) {
ch(i*10)
})
}
)
it(
'should be able to select with queued messages',
function (done) {
var chs = [chan(), chan()]
var remaining = chs.length
var i = -1
while (++i < 10) {
(function (i) {
chan.select.apply(null, chs)(function (err, ch) {
expect(ch).to.equal(chs[0])
ch.selected(function (err, val) {
expect(val).to.equal(i * 10)
if (--remaining === 0) {
done()
}
})
})
})(i)
}
var j = -1
while (++j < 10) {
chs[0](j * 10)
}
}
)
it(
'should be able to select with existing messages on the channels',
function (done) {
var ch1 = chan()
var ch2 = chan()
ch2(42)
chan.select(ch1, ch2)(function (err, ch) {
expect(ch).to.equal(ch2)
ch2.selected(function (err, val) {
expect(val).to.equal(42)
done()
})
})
}
)
it(
'should randomly choose a channel to return with multiple full channels',
function (done) {
var ch1 = chan()
var ch2 = chan()
// force the random selection to be the second channel
Math.random = function () { return 0.5 }
// fill up both the channels
ch1(21)
ch2(42)
// random selection should choose the second channel "randomly"
chan.select(ch1, ch2)(function (err, ch) {
expect(ch).to.equal(ch2)
ch2.selected(function (err, val) {
expect(val).to.equal(42)
done()
})
})
}
)
it (
'should wait for previously queued callbacks before selecting',
function (done) {
var ch1 = chan()
var ch2 = chan()
// queue a callback for ch1
ch1(function () {})
chan.select(ch1, ch2)(function (err, ch) {
expect(ch).to.be(ch2)
done()
})
ch1(74)
ch2(47)
}
)
})