How to mock a function using detox in react-native - react-native

Question

How to mock functions in react-native using detox.
I am using google sign in app and want to mock the function for google sign in
tried jest and #testinglibrary but there I am not able to get the elements by getText/getTestID for picker or other components. There is many things about testing in react-native but I am not able to find the right way to do it.
How to test a react native app where I am using google sign in and each page is fetching details about users from AWS database and displaying details for modification.
Currently i am using the following libraries
"#react-native-async-storage/async-storage": "^1.15.5",
"#react-native-google-signin/google-signin": "^7.0.0-alpha.3",
"#react-native-picker/picker": "^1.16.5",
"#react-navigation/bottom-tabs": "^6.0.4",
"#react-navigation/drawer": "^6.1.8",
"#react-navigation/native": "^6.0.6",
"#react-navigation/native-stack": "^6.0.4",
"add": "^2.0.6",
"react": "17.0.1",
"react-native": "0.64.2",
"react-native-elements": "^3.4.2",
"react-native-file-picker": "0.0.21",
"react-native-gesture-handler": "^1.10.3",
"react-native-pager-view": "^5.4.1",
"react-native-reanimated": "^2.2.3",
"react-native-safe-area-context": "^3.3.0",
"react-native-screens": "^3.5.0",
"react-native-tab-view": "^3.1.1",
"react-native-vector-icons": "^8.1.0"
},
"devDependencies": {
"#babel/core": "^7.14.8",
"#babel/runtime": "^7.14.8",
"#react-native-community/eslint-config": "^3.0.0",
"#testing-library/react-native": "^8.0.0",
"babel-jest": "^27.0.6",
"detox": "^18.20.3",
"eslint": "^7.31.0",
"jest": "^27.0.6",
"metro-react-native-babel-preset": "^0.66.2",
"react-test-renderer": "17.0.1"
},
"jest": {
"preset": "react-native",
"moduleNameMapper": {
".+\\.(css|styl|less|sass|scss|png|jpg|ttf|woff|woff2)$": "babel-jest"
},
"transformIgnorePatterns": [
"node_modules/(?!#ngrx|(?!deck.gl)|ng-dynamic)"
]
},
"detox": {
"configurations": {
"android.emu.debug": {
"binaryPath": "android/app/build/outputs/apk/debug/app-debug.apk",
"build": "cd android && gradlew clean assembleDebug assembleAndroidTest -DtestBuildType=debug && cd ..",
"type": "android.emulator",
"name": "Pixel_2_API_29"
}
},
"test-runner": "jest",
"testMatch": [
"<roots>/**/*.spec.js"
]
}

Answer 1

Have a look at the mocking guide for Detox.
Please note that you cannot apply mocking techniques familiar from the prior Jest experience, even though Detox runs on top of Jest, e.g.:
jest.mock('./src/myModule'); // NO, THIS WON'T WORK
All the mocking must be conducted with the help of Metro bundler, which powers React Native under the hood.