pull stream spec

What is a pull stream?

The source stream

• if it is passed a truthy abort param, it must call the callback with a truthy end param
• It must not call the callback more than once (before it has been called again)

The sink stream

• If the callback gets a truthy end param, it must not call source again
• It must not call the source multiple times before getting a callback

Both sources and sinks should work whether they are called synchronously or asynchronously.

install

npm install pull-stream-spec

example

var test = require('tape')
var S = require('pull-stream')
S.cat = require('pull-cat')
var spec = require('../')

// test a source stream
spec.source(test, S.values.bind(S, [1,2,3]))

// test a sink stream
function mySink () {
    return S.drain(function onData () {}, function onEnd (err) {
        // caught error
    })
}
spec.sink(test, mySink)

// compose a pipeline with a through stream that makes assertions
// about how it is called. Since it is a proxy to a source and sink,
// it could be used to test either.
test('I want to test this sink with special source streams', function (t) {
    t.plan(1)

    // emit 3 values then error
    var testSource = S.cat([
        S.values([1,2,3]),
        S.error(new Error('test'))
    ])

    var mySink = S.drain(function onData (d) {}, function onEnd (err) {
        // caught error, do nothing
    })

    t.doesNotThrow(
        S.bind(null,
            testSource,
            spec.through(),
            mySink
        ),
        'should not throw'
    )
})