Change to different function length check

[levibostian]

Today as I was using connect-sequence, I was hit with an exception:

[ integration]       ERROR: Extra: (none), message: str.split is not a function, stack: TypeError: str.split is not a function
[ integration]           at isErrorHandler (/Users/levibostian/code/ExpressjsBlanky/node_modules/connect-sequence/lib/ConnectSequence.js:238:18)
[ integration]           at nextHandler (/Users/levibostian/code/ExpressjsBlanky/node_modules/connect-sequence/lib/ConnectSequence.js:91:13)
[ integration]           at ConnectSequence.run (/Users/levibostian/code/ExpressjsBlanky/node_modules/connect-sequence/lib/ConnectSequence.js:67:22)

This crash occurred at the code:

function isErrorHandler (cb) {
  var str = cb.toString()
  var args = str.split('(')[1].split(')')[0].split(',')
  return args.length === 4
}

After debugging, I realized that cb is an instance of an express-validator middleware. For some reason, when calling cb.toString() the result was not a string, but another function according to the debugger.

So, after doing some research on "how to count the number of parameters in a function", I found this method that I used in this PR.

After running my unit and integration tests on my application, everything seems to work well without the crash. I also checked the debugger and cb.length returns an integer successfully. I expected a length of 3 for my express validator middleware and that is what successfully was returned back.

[rbecheras]

Hi !

Thank you for the PR.

Could you just fix the trailing spaces and push again to validate the travis CI please ?

lib/ConnectSequence.js
line 236:31	Trailing spaces not allowed.
✖ 1 errors	⚠ 0 warnings

https://travis-ci.org/sirap-group/connect-sequence/builds/551935612?utm_source=github_status&utm_medium=notification

Then I'll merge it.

[levibostian]

@rbecheras, done.

[coveralls]

Coverage remained the same at 100.0% when pulling c147555 on levibostian:error-handler-fix into 8b0490d on sirap-group:master.

[levibostian]

This PR is ready for another review, @rbecheras. Thanks!

[rbecheras]

Thank you very much @levibostian :)

I merge