Couldn't start backstop as a child process

I’m trying to use backstopjs into a express application. I’m creating dynamically configuration file using original file just overwriting the scenario (I wanna run just to one scenario in this case). So here the problem happens.

const createReference = (newSpec) => {
  const originalConfigFile = require('../tests/config.json');

  const tmpFile = '/tmp/new-config.json';
  const referencesPath = '/tmp/references';

  const newConfig = {
    ...omit(originalConfigFile, ['onBeforeScript', 'onReadyScript', 'scenarios', 'paths.bitmaps_reference']),
    scenarios: [newSpec],
    paths: {
      bitmaps_reference: "/tmp/references",
      bitmaps_test: "/tmp/bitmaps_test",
      casper_scripts: "/tmp/casper_scripts",
      html_report: "/tmp/html_report",
      ci_report: "/tmp/ci_report",
    }
  };

  fs.writeFile(tmpFile, JSON.stringify(newConfig, null, 2), (err) => {
    exec(`backstop reference --configPath=${tmpFile}`, (err, stdout, stderr) => {
      if (err) {
        console.log(stdout);
        return;
      }
      // do something else
    });
  });
}

When I run this same code (backstop reference --configPath=/tmp/new-config.json) separately from my express application, it’s sounds good, but in child process it returns:

BackstopJS loading config:  /tmp/new-spec.json

COMMAND | Executing core for `reference`
  clean | /tmp/references was cleaned.

Running CasperJS with:  [ '/Users/marciovicente/git/test-project/node_modules/backstopjs/capture/genBitmaps.js',
  '--engine=slimerjs',
  '--captureConfigFileName=/var/folders/m_/ydbqsgh94vlf0dwk_n1cfhv40000gn/T/capture/75b3b173ef6003982053521774d69d83008ea8e6.json' ]
CasperJS:  Debug is enabled!
CasperJS:  CREATING NEW REFERENCE FILES

Testing script failed with code: 1

An unexpected error occured. You may want to try setting the debug option to `true` in your config file.
COMMAND | Command `reference` ended with an error
COMMAND | Error: An unexpected error occured. You may want to try setting the debug option to `true` in your config file.
              at ChildProcess.<anonymous> (/Users/marciovicente/git/test-project/node_modules/backstopjs/core/util/createBitmaps.js:70:18)
              at emitTwo (events.js:106:13)
              at ChildProcess.emit (events.js:194:7)
              at maybeClose (internal/child_process.js:899:16)
              at Process.ChildProcess._handle.onexit (internal/child_process.js:226:5)

I’ve already tried to use the backstop package instead of run binary from child process but the error still happens.

Here is my config output (from /tmp/new-config.json)

{  
   "id":"prod_test",
   "viewports":[  
      {  
         "name":"default",
         "width":1024,
         "height":768
      }
   ],
   "readyEvent":null,
   "delay":500,
   "misMatchThreshold":0.1,
   "paths":{  
      "bitmaps_reference":"/tmp/references",
      "bitmaps_test":"/tmp/bitmaps_test",
      "casper_scripts":"/tmp/casper_scripts",
      "html_report":"/tmp/html_report",
      "ci_report":"/tmp/ci_report"
   },
   "casperFlags":[  

   ],
   "engine":"slimerjs",
   "report":[  
      "CI"
   ],
   "debug":true,
   "scenarios":[  
      {  
         "label":"Google",
         "url":"http://google.com"
      }
   ]
}

[klausbayrhammer]

Probably it’s the child process’ changed cwd? Or any ENVs changed?

[marciovicente]

Ok guys, I figured out what’s happening… I don’t know the reason, but the problem is when I’m running with slimerjs. I chose slimer to support all new frameworks (React client side render, for example). So, I’ll close this issue, and thank you for your attention @klausbayrhammer @garris 😃