How to set cross env variables to start tests berofe commit?

I have configured to run tests before commit. But it only works in Ubuntu.

Here what I have now:

 "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject",
    "test:all": "CI=true react-scripts test"
  },
  "husky": {
    "hooks": {
      "pre-commit": "npm run test:all"
    }
  },

How to set cross env variables to run them in any operating system?