Read custom app project name from gradle.properties (#52791)

dev/bots/test.dart

@@ -923,6 +923,7 @@ Future<void> _runHostOnlyDeviceLabTests() async {
     () => _runDevicelabTest('gradle_r8_test', environment: gradleEnvironment),
 
     () => _runDevicelabTest('module_host_with_custom_build_test', environment: gradleEnvironment, testEmbeddingV2: true),
+    () => _runDevicelabTest('module_custom_host_app_name_test', environment: gradleEnvironment),
     () => _runDevicelabTest('module_test', environment: gradleEnvironment, testEmbeddingV2: true),
     () => _runDevicelabTest('plugin_dependencies_test', environment: gradleEnvironment),
 

dev/integration_tests/android_custom_host_app/README.md

+# Android custom host app
+
+Android host app for a Flutter module created using
+```
+$ flutter create -t module hello
+```
+and placed in a sibling folder to (a clone of) the host app.
+Used by the `module_custom_host_app_name_test.dart` device lab test.

dev/integration_tests/android_custom_host_app/SampleApp/build.gradle

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 28
+
+    compileOptions {
+        sourceCompatibility 1.8
+        targetCompatibility 1.8
+    }
+
+    defaultConfig {
+        applicationId "io.flutter.add2app"
+        minSdkVersion 16
+        targetSdkVersion 28
+        versionCode 1
+        versionName "1.0"
+    }
+}
+
+dependencies {
+    implementation project(':flutter')
+    implementation 'androidx.appcompat:appcompat:1.1.0'
+}

dev/integration_tests/android_custom_host_app/SampleApp/src/main/AndroidManifest.xml

+<!-- Copyright 2014 The Flutter Authors. All rights reserved.
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file. -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    package="io.flutter.add2app">
+
+    <application android:allowBackup="false"
+        tools:ignore="GoogleAppIndexingWarning,MissingApplicationIcon">
+        <activity android:name=".MainActivity" />
+    </application>
+</manifest>

dev/integration_tests/android_custom_host_app/SampleApp/src/main/java/io/flutter/add2app/MainActivity.java

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.add2app;
+
+import android.os.Bundle;
+import androidx.appcompat.app.AppCompatActivity;
+import io.flutter.embedding.android.FlutterActivity;
+
+public class MainActivity extends FlutterActivity {
+}

dev/integration_tests/android_custom_host_app/build.gradle

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.5.0'
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

dev/integration_tests/android_custom_host_app/gradle.properties

+org.gradle.jvmargs=-Xmx1536m
+android.useAndroidX=true
+android.enableJetifier=true
+flutter.hostAppProjectName=SampleApp

dev/integration_tests/android_custom_host_app/gradle/wrapper/gradle-wrapper.properties

+#Mon Jun 25 14:13:36 CEST 2018
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-all.zip

dev/integration_tests/android_custom_host_app/local.properties

+## This file must *NOT* be checked into Version Control Systems,
+# as it contains information specific to your local configuration.
+#
+# Location of the SDK. This is only used by Gradle.
+# For customization when using a Version Control System, please read the
+# header note.
+#Thu Mar 26 18:32:27 GMT+07:00 2020
+sdk.dir=/Users/alekseyanisov/Library/Android/sdk

dev/integration_tests/android_custom_host_app/settings.gradle

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+include ':SampleApp'
+setBinding(new Binding([gradle: this]))
+evaluate(new File(settingsDir.parentFile, 'hello/.android/include_flutter.groovy'))

packages/flutter_tools/gradle/flutter.gradle

@@ -721,8 +721,9 @@ class FlutterPlugin implements Plugin<Project> {
                 return
             }
             // Flutter module included as a subproject in add to app.
-            Project appProject = project.rootProject.findProject(':app')
-            assert appProject != null
+            String hostAppProjectName = project.rootProject.hasProperty('flutter.hostAppProjectName') ? project.rootProject.property('flutter.hostAppProjectName')  : "app"
+            Project appProject = project.rootProject.findProject(":${hostAppProjectName}")
+            assert appProject != null : "Project :${hostAppProjectName} doesn't exist. To custom the host app project name, set `org.gradle.project.flutter.hostAppProjectName=<project-name>` in gradle.properties."
             appProject.afterEvaluate {
                 assert appProject.android != null
                 appProject.android.applicationVariants.all { appProjectVariant ->
@@ -750,7 +751,7 @@ class FlutterPlugin implements Plugin<Project> {
                     }
                     Task mergeAssets = project
                         .tasks
-                        .findByPath(":app:merge${appProjectVariant.name.capitalize()}Assets")
+                        .findByPath(":${hostAppProjectName}:merge${appProjectVariant.name.capitalize()}Assets")
                     assert mergeAssets
                     mergeAssets.dependsOn(copyFlutterAssetsTask)
                 }