instanceof checks, readable-stream and require-inject

index.js

const test = require('tap').test
const requireInject = require('require-inject')
const EventEmitter = require('events')

class NullSink extends EventEmitter {
  write () {
    return true
  }
  end () {
    this.emit('prefinish')
    this.emit('finish')
  }
}

test('requireInject', t => {
  t.plan(1)
  t.doesNotThrow(() => {
    // requireInject without any additional arguments loads the module but
    // maintains the require cache exactly as it was prior to calling it. 
    // As such, while it returns a the PassThrough class from
    // `readable-stream`, `readable-stream` and its dependencies will no
    // longer be in the cache.
    const stream = requireInject('readable-stream')
    const PassThrough = stream.PassThrough
    const pt = new PassThrough()
    // The error has already actually happened at this point.  When we
    // construct a new object here the constructor chain fails to execute
    // properly, due to the intanceof checks failing. 
    // WHY the instanceof check fails is not obvious to me because contrary
    // to my expectations there is no deferred loading…

    pt.pipe(new NullSink())
    pt.end('example')
    // We have to have activity on the stream to actuall crash, as can be seen here.
  })
})

test('require', t => {
  t.plan(1)
  t.doesNotThrow(() => {
    const stream = require('readable-stream')
    const PassThrough = stream.PassThrough
    const pt = new PassThrough()

    pt.pipe(new NullSink())
    pt.end('example')
  })
})

test('requireInject after require', t => {
  t.plan(2)
  t.doesNotThrow(() => {
    const stream = requireInject('readable-stream')
    const PassThrough = stream.PassThrough

    const pt = new PassThrough()

    pt.pipe(new NullSink())
    pt.end('example')
    // further use (once a version is cached from the previous test) works
    // because while we force a new copy of the top level `readable-stream`
    // object, the things it requires still come from cache.
  })
})

package.json

{
  "name": "readable-stream-incompat",
  "version": "1.0.0",
  "license": "ISC",
  "dependencies": {
    "readable-stream": "^2.3.3",
    "require-inject": "^1.4.2",
    "tap": "^10.7.2"
  }
}