• Install detox 9.0.6 or higher, detox-expo-helpers and expo-detox-hook (yarn or npm)
• Add detox configuration to package.json:

"detox": {
  "configurations": {
    "ios.sim": {
      "binaryPath": "bin/Exponent.app",
      "type": "ios.simulator",
      "name": "iPhone 7"
    }
  }
}

• Download the Expo Client iOS App from Expo.io/tools.
• Unzip the iOS IPA and rename the folder to Exponent.app. It'll have a file icon but will still be a folder.
• Create bin folder and put Exponent.app inside so it matches the binaryPath set above.
• Create an e2e and copy over the settings from the example app

The most important piece of this the reloadApp from detox-expo-helpers. Don't forget this.

const { reloadApp } = require('detox-expo-helpers');
// ...
beforeEach(async () => {
  await reloadApp();
});

• Usage with Android is currently TBD.

expo/with-detox-tests