Detox/docs/Guide.DebuggingInXcode.md

id, slug, title, sidebar_label

id	slug	title	sidebar_label
debugging-in-xcode	guide/debugging-in-xcode	Debugging in Xcode During Detox Tests	Debugging in Xcode During Detox Tests

Debugging in Xcode During Detox Tests

This is mostly useful for investigating weird crashes or when contributing to Detox itself. This workflow isn’t standard. Don’t use it unless you have a good reason.

Add Detox Framework to Your Project

• Go to node_modules/detox and extract Detox-ios-src.tbz

  

• Drag Detox-ios-src/Detox.xcodeproj into your Xcode project

  

• Go to your project settings → General and add Detox.framework to Frameworks, Libraries, and Embedded Content (make sure Embed & Sign is selected under Embed)

  

NOTE: Apps should not be submitted to the App Store with the Detox framework linked. Follow this guide only to debug Detox issues in your project. Once finished, make sure to remove Detox.framework from your project.

Add a "manual" configuration to your .detoxrc

Locate your .detoxrc config file or the corresponding detox section in your package.json and add a configuration similar to this one:

{
  "devices": {
    "simulator": {
      "type": "ios.simulator",
      "device": {
        "type": "<e.g., iPhone 12 Pro>"
      }
    }
  },
  "apps": {
    "ios.debug": {
      "type": "ios.app",
      "binaryPath": "<path to your app binary built before>"
    }
  },
  "configurations": {
    "ios.manual": {
      "device": "simulator",
      "app": "ios.debug",
      "behavior": {
        "launchApp": "manual"
      }
    }
  }
}

While the behavior section is a mandatory thing to include, there are a few more optional parameters to disable various side effects and make life easier when debugging:

   "behavior": {
     "launchApp": "manual"
   },
+  "session": {
+    "autoStart": true,
+    "debugSynchronization": 0,
+    "server": "ws://localhost:8099",
+    "sessionId": "test"
+  },
+  "artifacts": false

• Using a preconfigured session with an autostarting server removes the legwork of copying and pasting values to the instrumentation runner launch arguments dialog every time before any launch from the IDE. Otherwise, by default when the session object omitted, server and sessionId are randomly generated for every new test session.

  • The debugSynchronization: 0 override matters only if you have a global session config with debugSynchronization set to a positive integer value. Otherwise, it is not needed. The point is to disable regular app polling requests during debugging, since that only can hinder the debugging.

• Setting artifacts: false override also matters only if you have a global artifacts config. The motivation is to disable irrelevant taxing activities on the device such as capturing logs screenshots, videos and so on.

  • If your investigation addresses a specific artifact plugin glitch on the native side, then just disable all the other plugins. See Detox Configuration document for the reference.

Run a specific test

Usually, you would want to focus on a specific test suite to save time, e.g.:

detox test -c ios.manual e2e/someSuite.test.js --testTimeout 999999

Forwarding an increased testTimeout to Jest (as shown below) is recommended to avoid false timeout errors which are likely to be thrown if you spend too much time in debugging.

Also, if there is something you want to do step by step in JS code while debugging native, append --inspect-brk flag:

detox test -c ios.manual e2e/someSuite.test.js --inspect-brk

To learn more about debugging with --inspect-brk, refer to Debugging — Getting Started on the official Node.js website.

Afterwards, you should see your test suite starting as usual until it reaches the app launch, where Detox stops instead and prompts you to launch the app from the IDE:

detox[16804] INFO:  [SimulatorDriver.js] Waiting for you to manually launch your app in Xcode.
Make sure to pass the launch arguments listed below:
  -detoxServer ws://localhost:8099
  -detoxSessionId com.wix.detox-example

Press any key to continue...

You’ll need to run your app with the said arguments from Xcode:

Launching the app

Before you launch the app, make sure to put breakpoints at the points of interest, e.g.:

Launch the app with the debugger attached:

The moment you see the app is idle, go back to the Terminal where Detox is running and press any key. If you wish to terminate the process for some reason, use Ctrl+C. In a couple of seconds you are expected to see a confirmation from Detox, e.g.:

Found the app (com.wix.detox-example) with process ID = 16854. Proceeding...

Now the entire test will run as usual until it sends an action to the app, which gets trapped in your breakpoint. Now, when you are there, we wish you happy debugging!