mdtest/examples/chat/mdtest/chat.spec

{
  "devices": {
    "Bot1": {
      "app-root": "..",
      "app-path": "test_driver/chat_alice.dart"
    },
    "Bot2": {
      "app-root": "..",
      "app-path": "test_driver/chat_bob.dart"
    }
  }
}