stream.finished readonly doesn't fire if writable side is open

[mafintosh]

• Version: master (b53cae3, 14-pre)
• Platform: mac
• Subsystem: stream

stream.finished(duplex, { readable: true, writable: false }, cb) doesn't fire if writable side is finalising.

const stream = require('stream')

const dup = new stream.Duplex({
 final (cb) { }, // never close writable side for test purpose
 read () {
 this.push(null)
 }
})

dup.on('end', function () {
 console.log('end fired')
})

stream.finished(dup, { readable: true, writable: false }, function () {
 // doesn't fire in master
 console.log('not readable')
})

dup.end()
dup.resume()

[mafintosh]

cc @mcollina @ronag

[ronag]

This is because of willEmitClose. We incorrectly assume that a Duplex which we only care about the readable side of, will emit close.