When running npm test, is it necessary to place "CI=true" in the beginning of the test command?

My package.json contains

    "scripts": {
        "test": "CI=true react-scripts test --env=jsdom"
       }

What is the difference if I rewrite the code as

    "scripts": {
      "test": "react-scripts test --env=jsdom CI=true"
    }

Will the unit test fail when built?