Detox/docs/config/session.md

Session

Detox can either initialize a server using a generated configuration, or can be overridden with a manual configuration:

{
  "session": {
    "server": "ws://localhost:8099",
    "sessionId": "YourProjectSessionId"
  }
}

When you define a session config, the Detox server won’t start automatically anymore — it is assumed that you will be running it independently via detox run-server CLI command. Alternatively, you can set the autoStart property to be explicitly true:

   "session": {
+    "autoStart": true,
     "server": "ws://localhost:8099",
     "sessionId": "YourProjectSessionId"

Defining an explicit session config with server and sessionId also means you cannot use multiple workers, since the specified port will become busy for any test worker next to the first one to occupy it.

Session can be set also per device configuration — then it takes a higher priority over the global session config:

{
  "configurations": {
    "ios.sim.debug": {
      // ...
      "session": {
        "server": "ws://localhost:8099",
        "sessionId": "YourProjectSessionId"
      }
    }
  }
}

Also, you can specify an optional numeric debugSynchronization parameter (see also --debug-synchronization in detox-cli test section). When an action/expectation takes a significant amount time, use this option to print device synchronization status. The status will be printed if the action takes more than [N] ms to complete.

{
  "session": {
    "debugSynchronization": 20000
  }
}

To disable debugSynchronization explicitly, use 0.