Function useEnv

test/utils/helpers.ts:55–71

(key: string)

 * to set the value and reset the value
 */
export function useEnv(key: string): [(nextValue: string | undefined) => string | undefined, () => void] {
  const initialValue = process.env[key]
  const setValue = (nextValue: string | undefined) => (process.env[key] = nextValue)
  // Node automatically converts undefined to string 'undefined'
  // when assigning an environment variable.
  // which is why we need to delete it if it's supposed to be undefined
  // Source: https://stackoverflow.com/a/60147167
  const resetValue = () => {
    if (initialValue !== undefined) {
      process.env[key] = initialValue
    } else {
      delete process.env[key]
    }
  }

  return [setValue, resetValue]
}

/**
 * Helper function to get a random port.