add Detox integrations to Android RNTester app

Summary:
This diff adds required Detox integrations to the RNTester app to be able to run Detox end-to-end tests on the Android version of the app.

* Instructions at https://github.com/wix/Detox/blob/master/docs/Introduction.Android.md were followed.
* The `minSdkVersion` version for the app was bumped to 18, as required by Detox.
* I also added build and test configurations in `package.json`
*  The debug app is able to run some of the existing tests, but the release app instacrashes. I do not know the reason for the instacrash at this time.
* CI integrations to build and test the Android app will be added in future diffs

Changelog:
[Internal] add Detox integrations to the RNTester Android app

Reviewed By: TheSavior

Differential Revision: D19566834

fbshipit-source-id: 5dd506bbdbb426a5db18146e5dc7c450a27b1d0c

RNTester/android/app/build.gradle

@@ -120,10 +120,12 @@ android {
 
     defaultConfig {
         applicationId "com.facebook.react.uiapp"
-        minSdkVersion 16
+        minSdkVersion 18
         targetSdkVersion 29
         versionCode 1
         versionName "1.0"
+        testBuildType System.getProperty('testBuildType', 'debug')  // This will later be used to control the test apk build type
+        testInstrumentationRunner 'androidx.test.runner.AndroidJUnitRunner'
     }
     signingConfigs {
         release {
@@ -149,6 +151,8 @@ android {
             minifyEnabled enableProguardInReleaseBuilds
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
             signingConfig signingConfigs.release
+            // Detox-specific additions to pro-guard
+            proguardFile "${rootProject.projectDir}/../node_modules/detox/android/detox/proguard-rules-app.pro"
         }
     }
 }
@@ -187,4 +191,8 @@ dependencies {
     } else {
         jscImplementation 'org.webkit:android-jsc:+'
     }
+
+    // Use detox test library
+    androidTestImplementation('com.wix:detox:+') { transitive = true }
+    androidTestImplementation 'junit:junit:4.12'
 }

RNTester/android/app/src/androidTest/java/com/facebook/react/uiapp/DetoxTest.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// This uses instructions from
+// https://github.com/wix/Detox/blob/master/docs/Introduction.Android.md#4-create-android-test-class
+
+package com.facebook.react.uiapp;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.filters.LargeTest;
+import androidx.test.rule.ActivityTestRule;
+import com.wix.detox.Detox;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+@LargeTest
+public class DetoxTest {
+
+  @Rule
+  public ActivityTestRule<RNTesterActivity> mActivityRule =
+      new ActivityTestRule<>(RNTesterActivity.class, false, false);
+
+  @Test
+  public void runDetoxTests() {
+    Detox.runTests(mActivityRule);
+  }
+}

build.gradle.kts

@@ -25,6 +25,11 @@ allprojects {
         maven {
             url = uri("$rootDir/node_modules/jsc-android/dist")
         }
+        maven {
+            // https://github.com/wix/Detox/blob/master/docs/Introduction.Android.md
+            // All of Detox's artifacts are provided via the npm module
+            url = uri("$rootDir/node_modules/detox/Detox-android")
+        }
         mavenLocal()
         google()
         jcenter()

package.json

@@ -159,6 +159,25 @@
     "runner-config": "RNTester/e2e/config.json",
     "specs": "",
     "configurations": {
+      "android.emu.release": {
+        "binaryPath":     "RNTester/android/app/build/outputs/apk/hermes/release/app-hermes-x86-release.apk",
+        "testBinaryPath": "RNTester/android/app/build/outputs/apk/androidTest/hermes/release/app-hermes-release-androidTest.apk",
+        "build":
+        "./gradlew RNTester:android:app:assembleRelease RNTester:android:app:assembleAndroidTest -DtestBuildType=release",
+        "type": "android.emulator",
+        "device": {
+          "avdName": "Nexus_6_API_29"
+        }
+      },
+      "android.emu.debug": {
+        "binaryPath": "RNTester/android/app/build/outputs/apk/hermes/debug/app-hermes-x86-debug.apk",
+        "testBinaryPath": "RNTester/android/app/build/outputs/apk/androidTest/hermes/debug/app-hermes-debug-androidTest.apk",
+        "build": "./gradlew RNTester:android:app:assembleDebug RNTester:android:app:assembleAndroidTest -DtestBuildType=debug",
+        "type": "android.emulator",
+        "device": {
+          "avdName": "Nexus_6_API_29"
+        }
+    },
       "ios.sim.release": {
         "binaryPath": "RNTester/build/Build/Products/Release-iphonesimulator/RNTester.app/",
         "build": "xcodebuild -workspace RNTester/RNTesterPods.xcworkspace -scheme RNTester -configuration Release -sdk iphonesimulator -derivedDataPath RNTester/build -UseModernBuildSystem=NO -quiet",

template/android/build.gradle

@@ -11,9 +11,11 @@ buildscript {
         google()
         jcenter()
     }
+    ext.kotlinVersion = '1.3.0'
     dependencies {
         classpath("com.android.tools.build:gradle:3.5.3")
-
+        // for Detox
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
     }