nyc: Promise rejected with: 'cov_2itgu9hdrb is not defined

Nightmarejs converts functions passed to evaluate into strings, then evals them within the Electron/Chrome context. This means when the function is actually executed, Istanbul’s coverage info variables are not present in scope.

The solution is to use Istanbul’s coverage comment syntax:

browser
  .goto('http://...')
  .evaluate(
    /* istanbul ignore next */ 
    () => document.getElement('my-div').innerText
  )
  ...

@epyx25 in the example you posted you need:

class ScraperBase{
  /* istanbul ignore next */
  evaluate(selector) {
   return selector
  }

// ...
}

It’s important that you prevent instrumentation of the body of the function that will be sent to the browser, so the /* istanbul ignore next */ goes before the function declaration.

@farhan2106 I have some capacity this weekend, I will try to get back to you on this soon! Thanks for your patience.

@farhan2106 could you share a minimal reproduction of this bug with nightmare.js? I think you’ve probably found a legitimate edge-case with the instrumenter, which is returning a line counting variable rather than a promise.