Error class gotcha

[jasonblanchard]

It looks like the error classes don't behave like a Javascript Error:

it.only 'should return false if nonce already seen', (done) =>
      req =
        url: '/test'
        method: 'POST'
        connection:
          encrypted: undefined
        headers:
          host: 'localhost'
        body:
          lti_message_type: 'basic-lti-launch-request'
          lti_version: 'LTI-1p0'
          resource_link_id: 'http://link-to-resource.com/resource'
          oauth_customer_key: 'key'
          oauth_signature_method: 'HMAC-SHA1'
          oauth_timestamp: Math.round(Date.now()/1000)
          oauth_nonce: Date.now()+Math.random()*100

      #sign the fake request
      signature = @provider.signer.build_signature(req, req.body, 'secret')
      req.body.oauth_signature = signature

      @provider.valid_request req, (err, valid) =>
        should.not.exist err
        valid.should.equal true
        @provider.valid_request req, (err, valid) ->
          should.exist err
          console.log('Message: ', err.message);
          console.log('Stack: ', err.stack);
          err.should.be.instanceof(lti.Errors.NonceError)
          valid.should.equal false
          done()

which will print out:

Message:  Expired nonce
Stack:  undefined

vs changing this line to:

callback new Error('Expired nonce'), false

which will print out:

Message:  Expired nonce
Stack:  Error: Expired nonce
    at /Users/jason/oss/ims-lti/lib/provider.js:204:27
    at MemoryNonceStore.isNew (/Users/jason/oss/ims-lti/lib/memory-nonce-store.js:82:16)
    at Provider._valid_oauth (/Users/jason/oss/ims-lti/lib/provider.js:200:30)
    at Provider.valid_request (/Users/jason/oss/ims-lti/lib/provider.js:169:19)
    at Provider.valid_request (/Users/jason/oss/ims-lti/lib/provider.js:88:59)
    at /Users/jason/oss/ims-lti/test/Provider.coffee:326:19
    at /Users/jason/oss/ims-lti/lib/provider.js:207:18
    at /Users/jason/oss/ims-lti/lib/memory-nonce-store.js:98:20
    at MemoryNonceStore.setUsed (/Users/jason/oss/ims-lti/lib/memory-nonce-store.js:117:14)
    at MemoryNonceStore.isNew (/Users/jason/oss/ims-lti/lib/memory-nonce-store.js:85:19)

    at Provider._valid_oauth (/Users/jason/oss/ims-lti/lib/provider.js:200:30)
    at Provider.valid_request (/Users/jason/oss/ims-lti/lib/provider.js:169:19)
    at Provider.valid_request (/Users/jason/oss/ims-lti/lib/provider.js:88:59)
    at Context.<anonymous> (/Users/jason/oss/ims-lti/test/Provider.coffee:323:17)
    at callFnAsync (/Users/jason/oss/ims-lti/node_modules/mocha/lib/runnable.js:349:8)
    at Test.Runnable.run (/Users/jason/oss/ims-lti/node_modules/mocha/lib/runnable.js:301:7)
    at Runner.runTest (/Users/jason/oss/ims-lti/node_modules/mocha/lib/runner.js:422:10)
    at /Users/jason/oss/ims-lti/node_modules/mocha/lib/runner.js:528:12
    at next (/Users/jason/oss/ims-lti/node_modules/mocha/lib/runner.js:342:14)
    at /Users/jason/oss/ims-lti/node_modules/mocha/lib/runner.js:352:7
    at next (/Users/jason/oss/ims-lti/node_modules/mocha/lib/runner.js:284:14)
    at Immediate.<anonymous> (/Users/jason/oss/ims-lti/node_modules/mocha/lib/runner.js:320:5)
    at runCallback (timers.js:651:20)
    at tryOnImmediate (timers.js:624:5)
    at processImmediate [as _immediateCallback] (timers.js:596:5)

This can cause issues if calling code is expecting to find a useful stack trace or is using something like nested error stacks. There might be other subtle differences, too, but the lack of a stack trace is the one that puzzled me today.

It seems like the class inheritance isn't working as expected? It could be related to this coffeescript bug, but I know literally nothing about coffeescript, so hard to tell.