webpack + mocha, how to tell apart the environment

Question

I have this react + rails app that I use axios to communicate with the backend with, naturally I have to set up the CSRF token like this

export default axios.create({
  headers:{
    'X-CSRF-Token': document.querySelector('meta[name="csrf-token"]').getAttribute('content')
  }
})

But this screws up with my mocha test as document.querySelector doesn't exist in that environment; Is there anyway that I can specify like when mocha is running this file, it will just export axios, anything else, it's that axios.create(...)?

Like so:

export default TEST ? axios : axios.create(...)

Here is the scripts section of the package.json

      "scripts": {
        "test": "NODE_ENV=test mocha './app/**/*.spec.js' --compilers js:babel-core/register --require testSetup.js",
        "test:watch": "npm test -- --watch",
        "start": "node server.js"
      },

I am still new to mocha testing, and I don't have any mocha specific code in the webpack.config.js file.

Thanks a million!