Running with --coverage has different test output

[jsdario]

Hi all,

At the beginning I though I just needed troubleshoointg help, but I think I have found a bug.
I first opened a question on stackoverflow: http://stackoverflow.com/questions/43910088/jest-error-running-a-file-with-idx-operator

Then I realized that no errors where prompted without coverage, so the test suite, babel configuration and everything else seems right.

This is the error that appears with --coverage option:

I think the output shouldn't differ with or without coverage and thus this must be a bug.

[thymikee]

Does it happen on Jest@20?

[jsdario]

Sorry that it took a while for me to test on jest@20, just did and yes, the output is still different.

My issue started with [email protected] and jest@19
Latest test was [email protected] and jest@20
Node.js v7.4.0

[rogeliog]

This might be because Istanbul wraps your code in another function to calculate the coverage... facebook/idx#19 has more info, I'm closing in favor of facebook/idx#19

[jsdario]

In case someone else is looking for a suggestion / workaround:

I decided to use babel-plugin-idx only for production, since it's only supposed to be for a performance improvement

So with a .babelrc like the following you can avoid experiencing this issue, while profiting from idx

{
  "presets": [
    "flow",
    "react-native",
    "react-native-stage-0/decorator-support"
  ],
  "plugins": [
    "transform-inline-environment-variables"
  ],
  "env": {
    "production": {
      "plugins": [
        "idx",
        "transform-remove-console",
        "transform-inline-environment-variables"
      ]
    }
  }
}

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