Stubbing fs.readFileSync fails since 1.8.1

[rprieto]

In Sinon 1.7.0, the following works as expected:

sinon.stub(fs, 'readFileSync');

Later versions seem to throw:

TypeError: Cannot call method 'charCodeAt' of undefined

Unfortunately I can't seem to get a real stack trace for the error. Stubbing fs.readFile (not sync) works fine, and I'm running Node v0.10.25.

[rprieto]

Thanks for the test case.... I'll check again on my side to see if I can still reproduce it.

[mjashanks]

I can recreate this everytime - it is specific to coffee script....

fs = require("fs")
sinon = require("sinon")

sinon.stub(fs, "readFileSync")

crashes with coffee, but not node.

CoffeeScript v1.7.1
Sinon v1.10.3

Stack trace...

TypeError: Cannot call method 'charCodeAt' of undefined
at Object.exports.compileFile (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\node_modules\coffee-script\lib\coffee-script\coffee-script.js:207:20)
at getSourceMap (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\node_modules\coffee-script\lib\coffee-script\coffee-script.js:314:22)
at getSourceMapping (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\node_modules\coffee-script\lib\coffee-script\coffee-script.js:322:19)
at formatSourcePosition (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\node_modules\coffee-script\lib\coffee-script\coffee-script.js:274:16)
at C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\node_modules\coffee-script\lib\coffee-script\coffee-script.js:340:34
at Function.Error.prepareStackTrace (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\node_modules\coffee-script\lib\coffee-script\coffee-script.js:343:7)
at [object Object].jasmine.Spec.fail (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\lib\jasmine-node/jasmine-1.3.1.js:2405:22)
at [object Object].jasmine.Block.execute (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\lib\jasmine-node/jasmine-1.3.1.js:1147:17)
at [object Object].jasmine.Queue.next (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\lib\jasmine-node/jasmine-1.3.1.js:2177:31)
at [object Object]._onTimeout (C:\Users\Michael\AppData\Roaming\npm\node_modules\jasmine-node\lib\jasmine-node/jasmine-1.3.1.js:2167:18)

[roc]

I also get this issue, in javascript... what should I add to usefully prove this?

[fearphage]

Is the code open source? Have you tried upgrading to a later version of sinon?

[roc]

@fearphage didn't have any free time to reproduce this until now. Here's an example with proxyquire, which I feel maybe muddies the waters of what's happening here, but I'd hoped it might be useful nonetheless:

https://github.com/roc/sinon-filesync

[fearphage]

@roc Your test case is broken. There are no passing tests. Fix it and I'll check it out.

➜  sinon-filesync git:(master) mocha         


  loading a file and printing it
    1) should say hello m8

  replace file contents
    2) "before all" hook


  0 passing (13ms)
  2 failing

  1) loading a file and printing it should say hello m8:
     TypeError: Cannot read property 'charCodeAt' of undefined
      at Object.stripBOM (internal/module.js:48:14)
      at require (internal/module.js:20:19)
      at Context.it (test/index.js:11:17)

  2) replace file contents "before all" hook:
     TypeError: Cannot read property 'charCodeAt' of undefined
      at Object.stripBOM (internal/module.js:48:14)
      at Object.require.extensions.(anonymous function) (node_modules/proxyquire/lib/proxyquire.js:259:43)
      at Proxyquire._withoutCache (node_modules/proxyquire/lib/proxyquire.js:179:12)
      at Proxyquire.load (node_modules/proxyquire/lib/proxyquire.js:136:15)
      at Context.before (test/index.js:22:11)

[fearphage]

'use strict'

const file = require('fs').readFileSync(
  __dirname + '/file.txt', 'utf8'
);

module.exports = `hello ${file}`;

The way your code is written you'll never be able to mock it out without something like proxyquire. You're calling functions at import-time which is generally a bad idea. To rephrase, as soon as someone require's your file, you start executing code. That's suboptimal. If you altered your code a bit, it would make it much easier to test and much more friendly for other people to use.

const fs = require('fs');

module.exports = function() {
  return `hello ${fs.readFileSync(...)}`;
};

Here's an example of it working for someone else:

http://stackoverflow.com/questions/18044737/mock-fs-readdir-for-testing