Detox/docs/Guide.ProGuardConfiguration.md

id, slug

id	slug
proguard-configuration	guide/proguard-configuration

ProGuard configuration

:::tip

You can skip this guide if you are working solely with debug builds (android.emu.debug, etc.), but as soon as you move to the release builds, where the native code gets minified and obfuscated, you are going to have problems with Detox if you leave your ProGuard rules not configured.

:::

Since Detox relies on Android Reflection API to integrate with React Native on Android, you should keep ProGuard minification under tight control. Otherwise, you’ll be seeing Detox crashing or hanging up infinitely upon an attempt to run tests with your app built in release mode.

To fix that, you’d need to return to your app build script:

     buildTypes {
     …
// highlight-next-line
         release {
             minifyEnabled true

// highlight-next-line
             proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
// highlight-next-line
+            proguardFile "${rootProject.projectDir}/../node_modules/detox/android/detox/proguard-rules-app.pro"
         }
     }

1. release build type is usually expected to have ProGuard enabled
2. Typical pro-guard definitions. Check out Android docs to get to know more.
3. Detox-specific additions to pro-guard

⚠️ Note: In order for Detox to be able to work properly, in proguard-rules-app.pro, it effectively declares rules that retain most of React-Native’s code (i.e. keep it unminified, unobfuscated) in your production APK.

Though generally speaking, this should not be an issue (as React-Native is an open-source project), there are ways around that, if it bothers you. For example, running your E2E over a build-type specifically designed to run E2E tests using Detox would do the trick – roughly, like so (in app/build.gradle):

    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

            signingConfig signingConfigs.release
        }
        releaseE2E {
            initWith release
            setMatchingFallbacks('release')

            proguardFile "${rootProject.projectDir}/../node_modules/detox/android/detox/proguard-rules-app.pro"
        }
    }

Here we utilize Gradle’s initWith to easily define releaseE2E in a way that is identical to the release build-type, with the exception of considering Detox' proguard-rules-app.pro in the minification process.

Following the example, you would then have to build your app using gradlew assembleReleaseE2E rather than gradlew assembleRelease before running Detox, and instruct Detox (i.e. via binaryPath in the Detox configuration file) to use the APK resulted specifically by that Gradle target (e.g. in app/build/apk/releaseE2E/app-releaseE2E.apk instead of the equivalent app/build/apk/release/app-release.apk).

Note: if your app contains flavors – that makes things a bit trickier, but the approach can generally be adjusted to support that as well.

Last but not least: If you’re having issue with Detox' ProGuard rules, please report them here. A special thanks to @GEllickson-Hover for reporting issues related to obfuscation in #2431.