.firebaserc file example for multiple targets under one project

.firebaserc

{
  "projects": {
    "default": "project-name"
  },
  "targets": {
    "project-name": {
      "hosting": {
        "production": [
          "project-name"
        ],
        "test": [
          "project-name-test"
        ],
        "staging": [
          "project-name-staging"
        ]
      }
    }
  }
}