[flutter_tools] Refactor DeferredComponents validator and add build target (#76400)

packages/flutter_tools/lib/src/android/deferred_components_gen_snapshot_validator.dart

+// 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.
+
+// @dart = 2.8
+
+import 'package:xml/xml.dart';
+import 'package:yaml/yaml.dart';
+
+import '../base/deferred_component.dart';
+import '../base/error_handling_io.dart';
+import '../base/file_system.dart';
+import '../build_system/build_system.dart';
+import 'deferred_components_validator.dart';
+
+/// A class to configure and run deferred component setup verification checks
+/// and tasks.
+///
+/// Once constructed, checks and tasks can be executed by calling the respective
+/// methods. The results of the checks are stored internally and can be
+/// displayed to the user by calling [displayResults].
+class DeferredComponentsGenSnapshotValidator extends DeferredComponentsValidator {
+  /// Constructs a validator instance.
+  ///
+  /// The [env] property is used to locate the project files that are checked.
+  ///
+  /// The [templatesDir] parameter is optional. If null, the tool's default
+  /// templates directory will be used.
+  ///
+  /// When [exitOnFail] is set to true, the [handleResults] and [attemptToolExit]
+  /// methods will exit the tool when this validator detects a recommended
+  /// change. This defaults to true.
+  DeferredComponentsGenSnapshotValidator(Environment env, {
+    bool exitOnFail = true,
+    String title,
+  }) : super(env, exitOnFail: exitOnFail, title: title);
+
+  // The key used to identify the metadata element as the loading unit id to
+  // deferred component mapping.
+  static const String _mappingKey = 'io.flutter.embedding.engine.deferredcomponents.DeferredComponentManager.loadingUnitMapping';
+
+  /// Checks if the base module `app`'s `AndroidManifest.xml` contains the
+  /// required meta-data that maps loading units to deferred components.
+  ///
+  /// Returns true if the check passed with no recommended changes, and false
+  /// otherwise.
+  ///
+  /// Flutter engine uses a manifest meta-data mapping to determine which
+  /// deferred component includes a particular loading unit id. This method
+  /// checks if `app`'s `AndroidManifest.xml` contains this metadata. If not, it
+  /// will generate a modified AndroidManifest.xml with the correct metadata
+  /// entry.
+  ///
+  /// An example mapping:
+  ///
+  ///   2:componentA,3:componentB,4:componentC
+  ///
+  /// Where loading unit 2 is included in componentA, loading unit 3 is included
+  /// in componentB, and loading unit 4 is included in componentC.
+  bool checkAppAndroidManifestComponentLoadingUnitMapping(List<DeferredComponent> components, List<LoadingUnit> generatedLoadingUnits) {
+    final Directory androidDir = env.projectDir.childDirectory('android');
+    inputs.add(env.projectDir.childFile('pubspec.yaml'));
+
+    // We do not use the Xml package to handle the writing, as we do not want to
+    // erase any user applied formatting and comments. The changes can be
+    // applied with dart io and custom parsing.
+    final File appManifestFile = androidDir
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childFile('AndroidManifest.xml');
+    inputs.add(appManifestFile);
+    if (!appManifestFile.existsSync()) {
+      invalidFiles[appManifestFile.path] = 'Error: $appManifestFile does not '
+        'exist or could not be found. Please ensure an AndroidManifest.xml '
+        'exists for the app\'s base module.';
+      return false;
+    }
+    XmlDocument document;
+    try {
+      document = XmlDocument.parse(appManifestFile.readAsStringSync());
+    } on XmlParserException {
+      invalidFiles[appManifestFile.path] = 'Error parsing $appManifestFile '
+        'Please ensure that the android manifest is a valid XML document and '
+        'try again.';
+      return false;
+    } on FileSystemException {
+      invalidFiles[appManifestFile.path] = 'Error reading $appManifestFile '
+        'even though it exists. Please ensure that you have read permission for '
+        'this file and try again.';
+      return false;
+    }
+    // Create loading unit mapping.
+    final Map<int, String> mapping = <int, String>{};
+    for (final DeferredComponent component in components) {
+      component.assignLoadingUnits(generatedLoadingUnits);
+      for (final LoadingUnit unit in component.loadingUnits) {
+        if (!mapping.containsKey(unit.id)) {
+          mapping[unit.id] = component.name;
+        }
+      }
+    }
+    // Encode the mapping as a string.
+    final StringBuffer mappingBuffer = StringBuffer();
+    for (final int key in mapping.keys) {
+      mappingBuffer.write('$key:${mapping[key]},');
+    }
+    String encodedMapping = mappingBuffer.toString();
+    // remove trailing comma.
+    encodedMapping = encodedMapping.substring(0, encodedMapping.length - 1);
+    // Check for existing metadata entry and see if needs changes.
+    bool exists = false;
+    bool modified = false;
+    for (final XmlElement metaData in document.findAllElements('meta-data')) {
+      final String name = metaData.getAttribute('android:name');
+      if (name == _mappingKey) {
+        exists = true;
+        final String storedMappingString = metaData.getAttribute('android:value');
+        if (storedMappingString != encodedMapping) {
+          metaData.setAttribute('android:value', encodedMapping);
+          modified = true;
+        }
+      }
+    }
+    if (!exists) {
+      // Create an meta-data XmlElement that contains the mapping.
+      final XmlElement mappingMetadataElement = XmlElement(XmlName.fromString('meta-data'),
+        <XmlAttribute>[
+          XmlAttribute(XmlName.fromString('android:name'), _mappingKey),
+          XmlAttribute(XmlName.fromString('android:value'), encodedMapping),
+        ],
+      );
+      for (final XmlElement application in document.findAllElements('application')) {
+        application.children.add(mappingMetadataElement);
+        break;
+      }
+    }
+    if (!exists || modified) {
+      final File manifestOutput = outputDir
+        .childDirectory('app')
+        .childDirectory('src')
+        .childDirectory('main')
+        .childFile('AndroidManifest.xml');
+      ErrorHandlingFileSystem.deleteIfExists(manifestOutput);
+      manifestOutput.createSync(recursive: true);
+      manifestOutput.writeAsStringSync(document.toXmlString(pretty: true), flush: true);
+      modifiedFiles.add(manifestOutput.path);
+      return false;
+    }
+    return true;
+  }
+
+  /// Compares the provided loading units against the contents of the
+  /// `deferred_components_loading_units.yaml` file.
+  ///
+  /// Returns true if a loading unit cache file exists and all loading units
+  /// match, and false otherwise.
+  ///
+  /// This method will parse the cached loading units file if it exists and
+  /// compare it to the provided generatedLoadingUnits. It will distinguish
+  /// between newly added loading units and no longer existing loading units. If
+  /// the cache file does not exist, then all generatedLoadingUnits will be
+  /// considered new.
+  bool checkAgainstLoadingUnitsCache(
+      List<LoadingUnit> generatedLoadingUnits) {
+    final List<LoadingUnit> cachedLoadingUnits = _parseLodingUnitsCache(env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName));
+    loadingUnitComparisonResults = <String, dynamic>{};
+    final Set<LoadingUnit> unmatchedLoadingUnits = <LoadingUnit>{};
+    final List<LoadingUnit> newLoadingUnits = <LoadingUnit>[];
+    if (generatedLoadingUnits == null || cachedLoadingUnits == null) {
+      loadingUnitComparisonResults['new'] = newLoadingUnits;
+      loadingUnitComparisonResults['missing'] = unmatchedLoadingUnits;
+      loadingUnitComparisonResults['match'] = false;
+      return false;
+    }
+    unmatchedLoadingUnits.addAll(cachedLoadingUnits);
+    final Set<int> addedNewIds = <int>{};
+    for (final LoadingUnit genUnit in generatedLoadingUnits) {
+      bool matched = false;
+      for (final LoadingUnit cacheUnit in cachedLoadingUnits) {
+        if (genUnit.equalsIgnoringPath(cacheUnit)) {
+          matched = true;
+          unmatchedLoadingUnits.remove(cacheUnit);
+          break;
+        }
+      }
+      if (!matched && !addedNewIds.contains(genUnit.id)) {
+        newLoadingUnits.add(genUnit);
+        addedNewIds.add(genUnit.id);
+      }
+    }
+    loadingUnitComparisonResults['new'] = newLoadingUnits;
+    loadingUnitComparisonResults['missing'] = unmatchedLoadingUnits;
+    loadingUnitComparisonResults['match'] = newLoadingUnits.isEmpty && unmatchedLoadingUnits.isEmpty;
+    return loadingUnitComparisonResults['match'] as bool;
+  }
+
+  List<LoadingUnit> _parseLodingUnitsCache(File cacheFile) {
+    final List<LoadingUnit> loadingUnits = <LoadingUnit>[];
+    inputs.add(cacheFile);
+    if (!cacheFile.existsSync()) {
+      return loadingUnits;
+    }
+    final YamlMap data = loadYaml(cacheFile.readAsStringSync()) as YamlMap;
+    // validate yaml format.
+    if (!data.containsKey('loading-units')) {
+      invalidFiles[cacheFile.path] = 'Invalid loading units yaml file, \'loading-units\' '
+                                       'entry did not exist.';
+      return loadingUnits;
+    } else {
+      if (data['loading-units'] is! YamlList && data['loading-units'] != null) {
+        invalidFiles[cacheFile.path] = 'Invalid loading units yaml file, \'loading-units\' '
+                                         'is not a list.';
+        return loadingUnits;
+      }
+      if (data['loading-units'] != null) {
+        for (final dynamic loadingUnitData in data['loading-units']) {
+          if (loadingUnitData is! YamlMap) {
+            invalidFiles[cacheFile.path] = 'Invalid loading units yaml file, \'loading-units\' '
+                                             'is not a list of maps.';
+            return loadingUnits;
+          }
+          final YamlMap loadingUnitDataMap = loadingUnitData as YamlMap;
+          if (loadingUnitDataMap['id'] == null) {
+            invalidFiles[cacheFile.path] = 'Invalid loading units yaml file, all '
+                                             'loading units must have an \'id\'';
+            return loadingUnits;
+          }
+          if (loadingUnitDataMap['libraries'] != null) {
+            if (loadingUnitDataMap['libraries'] is! YamlList) {
+              invalidFiles[cacheFile.path] = 'Invalid loading units yaml file, \'libraries\' '
+                                               'is not a list.';
+              return loadingUnits;
+            }
+            for (final dynamic node in loadingUnitDataMap['libraries'] as YamlList) {
+              if (node is! String) {
+                invalidFiles[cacheFile.path] = 'Invalid loading units yaml file, \'libraries\' '
+                                                 'is not a list of strings.';
+                return loadingUnits;
+              }
+            }
+          }
+        }
+      }
+    }
+
+    // Parse out validated yaml.
+    if (data.containsKey('loading-units')) {
+      if (data['loading-units'] != null) {
+        for (final dynamic loadingUnitData in data['loading-units']) {
+          final YamlMap loadingUnitDataMap = loadingUnitData as YamlMap;
+          final List<String> libraries = <String>[];
+          if (loadingUnitDataMap['libraries'] != null) {
+            for (final dynamic node in loadingUnitDataMap['libraries'] as YamlList) {
+              libraries.add(node as String);
+            }
+          }
+          loadingUnits.add(
+              LoadingUnit(
+                id: loadingUnitDataMap['id'] as int,
+                path: null,
+                libraries: libraries,
+              ));
+        }
+      }
+    }
+    return loadingUnits;
+  }
+
+  /// Writes the provided generatedLoadingUnits as `deferred_components_loading_units.yaml`
+  ///
+  /// This cache file is used to detect any changes in the loading units
+  /// produced by gen_snapshot. Running [checkAgainstLoadingUnitCache] with a
+  /// mismatching or missing cache will result in a failed validation. This
+  /// prevents unexpected changes in loading units causing misconfigured
+  /// deferred components.
+  void writeLoadingUnitsCache(List<LoadingUnit> generatedLoadingUnits) {
+    generatedLoadingUnits ??= <LoadingUnit>[];
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    outputs.add(cacheFile);
+    ErrorHandlingFileSystem.deleteIfExists(cacheFile);
+    cacheFile.createSync(recursive: true);
+
+    final StringBuffer buffer = StringBuffer();
+    buffer.write('''
+# ==============================================================================
+# The contents of this file are automatically generated and it is not
+# recommended to modify this file manually.
+# ==============================================================================
+#
+# In order to prevent unexpected splitting of deferred apps, this file records
+# the last generated set of loading units. It only possible to obtain the final
+# configuration of loading units after compilation is complete. This means
+# improperly setup deferred imports can only be detected after compilation.
+#
+# This file allows the build tool to detect any changes in the generated
+# loading units. During the next build attempt, loading units in this file are
+# compared against the newly generated loading units to check for any new or
+# removed loading units. In the case where loading units do not match, the build
+# will fail and ask the developer to verify that the `deferred-components`
+# configuration in `pubspec.yaml` is correct. Developers should make any
+# necessary changes to integrate new and changed loading units or remove no
+# longer existing loading units from the configuration. The build command should
+# then be re-run to continue the build process.
+#
+# Sometimes, changes to the generated loading units may be unintentional. If
+# the list of loading units in this file is not what is expected, the app's
+# deferred imports should be reviewed. Third party plugins and packages may
+# also introduce deferred imports that result in unexpected loading units.
+loading-units:
+''');
+    final Set<int> usedIds = <int>{};
+    for (final LoadingUnit unit in generatedLoadingUnits) {
+      if (usedIds.contains(unit.id)) {
+        continue;
+      }
+      buffer.write('  - id: ${unit.id}\n');
+      if (unit.libraries != null && unit.libraries.isNotEmpty) {
+        buffer.write('    libraries:\n');
+        for (final String lib in unit.libraries) {
+          buffer.write('      - $lib\n');
+        }
+      }
+      usedIds.add(unit.id);
+    }
+    cacheFile.writeAsStringSync(buffer.toString(), flush: true);
+  }
+}

packages/flutter_tools/lib/src/android/deferred_components_setup_validator.dart → packages/flutter_tools/lib/src/android/deferred_components_prebuild_validator.dart

@@ -6,17 +6,15 @@
 
 import 'package:meta/meta.dart';
 import 'package:xml/xml.dart';
-import 'package:yaml/yaml.dart';
 
-import '../base/common.dart';
 import '../base/deferred_component.dart';
 import '../base/error_handling_io.dart';
 import '../base/file_system.dart';
-import '../base/terminal.dart';
 import '../build_system/build_system.dart';
 import '../globals.dart' as globals;
 import '../project.dart';
 import '../template.dart';
+import 'deferred_components_validator.dart';
 
 /// A class to configure and run deferred component setup verification checks
 /// and tasks.
@@ -24,7 +22,7 @@ import '../template.dart';
 /// Once constructed, checks and tasks can be executed by calling the respective
 /// methods. The results of the checks are stored internally and can be
 /// displayed to the user by calling [displayResults].
-class DeferredComponentsSetupValidator {
+class DeferredComponentsPrebuildValidator extends DeferredComponentsValidator {
   /// Constructs a validator instance.
   ///
   /// The [env] property is used to locate the project files that are checked.
@@ -35,78 +33,14 @@ class DeferredComponentsSetupValidator {
   /// When [exitOnFail] is set to true, the [handleResults] and [attemptToolExit]
   /// methods will exit the tool when this validator detects a recommended
   /// change. This defaults to true.
-  DeferredComponentsSetupValidator(this.env, {
-    this.exitOnFail = true,
+  DeferredComponentsPrebuildValidator(Environment env, {
+    bool exitOnFail = true,
     String title,
     Directory templatesDir,
-  }) : _outputDir = env.projectDir
-        .childDirectory('build')
-        .childDirectory(kDeferredComponentsTempDirectory),
-      _inputs = <File>[],
-      _outputs = <File>[],
-      _title = title ?? 'Deferred components setup verification',
-      _templatesDir = templatesDir,
-      _generatedFiles = <String>[],
-      _modifiedFiles = <String>[],
-      _invalidFiles = <String, String>{},
-      _diffLines = <String>[];
+  }) : _templatesDir = templatesDir,
+       super(env, exitOnFail: exitOnFail, title: title);
 
-  /// The build environment that should be used to find the input files to run
-  /// checks against.
-  ///
-  /// The checks in this class are meant to be used as part of a build process,
-  /// so an environment should be available.
-  final Environment env;
-
-  /// When true, failed checks and tasks will result in [attemptToolExit]
-  /// triggering [throwToolExit].
-  final bool exitOnFail;
-
-  /// The name of the golden file that tracks the latest loading units
-  /// generated.
-  @visibleForTesting
-  static const String kDeferredComponentsGoldenFileName = 'deferred_components_golden.yaml';
-  /// The directory in the build folder to generate missing/modified files into.
-  @visibleForTesting
-  static const String kDeferredComponentsTempDirectory = 'android_deferred_components_setup_files';
-
-  final String _title;
   final Directory _templatesDir;
-  final Directory _outputDir;
-  // Files that were newly generated by this validator.
-  final List<String> _generatedFiles;
-  // Existing files that were modified by this validator.
-  final List<String> _modifiedFiles;
-  // Files that were invalid and unable to be checked. These files are input
-  // files that the validator tries to read rather than output files the
-  // validator generates. The key is the file name and the value is the message
-  // or reason it was invalid.
-  final Map<String, String> _invalidFiles;
-  // Output of the diff task.
-  // TODO(garyq): implement the diff task.
-  final List<String> _diffLines;
-  // Tracks the new and missing loading units.
-  Map<String, dynamic> _goldenComparisonResults;
-
-  /// All files read by the validator.
-  List<File> get inputs => _inputs;
-  final List<File> _inputs;
-
-  /// All files output by the validator.
-  List<File> get outputs => _outputs;
-  final List<File> _outputs;
-
-  /// Returns true if there were any recommended changes that should
-  /// be applied.
-  ///
-  /// Retuns false if no problems or recommendations were detected.
-  ///
-  /// If no checks are run, then this will default to false and will remain so
-  /// until a failing check finishes running.
-  bool get changesNeeded => _generatedFiles.isNotEmpty
-    || _modifiedFiles.isNotEmpty
-    || _invalidFiles.isNotEmpty
-    || (_goldenComparisonResults != null && !(_goldenComparisonResults['match'] as bool));
 
   /// Checks if an android dynamic feature module exists for each deferred
   /// component.
@@ -122,6 +56,10 @@ class DeferredComponentsSetupValidator {
   /// This method does not check if the contents of either of the files are
   /// valid, as there are many ways that they can be validly configured.
   Future<bool> checkAndroidDynamicFeature(List<DeferredComponent> components) async {
+    inputs.add(env.projectDir.childFile('pubspec.yaml'));
+    if (components == null || components.isEmpty) {
+      return false;
+    }
     bool changesMade = false;
     for (final DeferredComponent component in components) {
       final _DeferredComponentAndroidFiles androidFiles = _DeferredComponentAndroidFiles(
@@ -133,135 +71,20 @@ class DeferredComponentsSetupValidator {
         // generate into temp directory
         final Map<String, List<File>> results =
           await androidFiles.generateFiles(
-            alternateAndroidDir: _outputDir,
+            alternateAndroidDir: outputDir,
             clearAlternateOutputDir: true,
           );
         for (final File file in results['outputs']) {
-          _generatedFiles.add(file.path);
+          generatedFiles.add(file.path);
           changesMade = true;
         }
-        _outputs.addAll(results['outputs']);
-        _inputs.addAll(results['inputs']);
+        outputs.addAll(results['outputs']);
+        inputs.addAll(results['inputs']);
       }
     }
     return !changesMade;
   }
 
-
-  // The key used to identify the metadata element as the loading unit id to
-  // deferred component mapping.
-  static const String _mappingKey = 'io.flutter.embedding.engine.deferredcomponents.DeferredComponentManager.loadingUnitMapping';
-
-  /// Checks if the base module `app`'s `AndroidManifest.xml` contains the
-  /// required meta-data that maps loading units to deferred components.
-  ///
-  /// Returns true if the check passed with no recommended changes, and false
-  /// otherwise.
-  ///
-  /// Flutter engine uses a manifest meta-data mapping to determine which
-  /// deferred component includes a particular loading unit id. This method
-  /// checks if `app`'s `AndroidManifest.xml` contains this metadata. If not, it
-  /// will generate a modified AndroidManifest.xml with the correct metadata
-  /// entry.
-  ///
-  /// An example mapping:
-  ///
-  ///   2:componentA,3:componentB,4:componentC
-  ///
-  /// Where loading unit 2 is included in componentA, loading unit 3 is included
-  /// in componentB, and loading unit 4 is included in componentC.
-  bool checkAppAndroidManifestComponentLoadingUnitMapping(List<DeferredComponent> components, List<LoadingUnit> generatedLoadingUnits) {
-    final Directory androidDir = env.projectDir.childDirectory('android');
-
-    // We do not use the Xml package to handle the writing, as we do not want to
-    // erase any user applied formatting and comments. The changes can be
-    // applied with dart io and custom parsing.
-    final File appManifestFile = androidDir
-      .childDirectory('app')
-      .childDirectory('src')
-      .childDirectory('main')
-      .childFile('AndroidManifest.xml');
-    _inputs.add(appManifestFile);
-    if (!appManifestFile.existsSync()) {
-      _invalidFiles[appManifestFile.path] = 'Error: $appManifestFile does not '
-        'exist or could not be found. Please ensure an AndroidManifest.xml '
-        'exists for the app\'s base module.';
-      return false;
-    }
-    XmlDocument document;
-    try {
-      document = XmlDocument.parse(appManifestFile.readAsStringSync());
-    } on XmlParserException {
-      _invalidFiles[appManifestFile.path] = 'Error parsing $appManifestFile '
-        'Please ensure that the android manifest is a valid XML document and '
-        'try again.';
-      return false;
-    } on FileSystemException {
-      _invalidFiles[appManifestFile.path] = 'Error reading $appManifestFile '
-        'even though it exists. Please ensure that you have read permission for '
-        'this file and try again.';
-      return false;
-    }
-    // Create loading unit mapping.
-    final Map<int, String> mapping = <int, String>{};
-    for (final DeferredComponent component in components) {
-      component.assignLoadingUnits(generatedLoadingUnits);
-      for (final LoadingUnit unit in component.loadingUnits) {
-        if (!mapping.containsKey(unit.id)) {
-          mapping[unit.id] = component.name;
-        }
-      }
-    }
-    // Encode the mapping as a string.
-    final StringBuffer mappingBuffer = StringBuffer();
-    for (final int key in mapping.keys) {
-      mappingBuffer.write('$key:${mapping[key]},');
-    }
-    String encodedMapping = mappingBuffer.toString();
-    // remove trailing comma.
-    encodedMapping = encodedMapping.substring(0, encodedMapping.length - 1);
-    // Check for existing metadata entry and see if needs changes.
-    bool exists = false;
-    bool modified = false;
-    for (final XmlElement metaData in document.findAllElements('meta-data')) {
-      final String name = metaData.getAttribute('android:name');
-      if (name == _mappingKey) {
-        exists = true;
-        final String storedMappingString = metaData.getAttribute('android:value');
-        if (storedMappingString != encodedMapping) {
-          metaData.setAttribute('android:value', encodedMapping);
-          modified = true;
-        }
-      }
-    }
-    if (!exists) {
-      // Create an meta-data XmlElement that contains the mapping.
-      final XmlElement mappingMetadataElement = XmlElement(XmlName.fromString('meta-data'),
-        <XmlAttribute>[
-          XmlAttribute(XmlName.fromString('android:name'), _mappingKey),
-          XmlAttribute(XmlName.fromString('android:value'), encodedMapping),
-        ],
-      );
-      for (final XmlElement application in document.findAllElements('application')) {
-        application.children.add(mappingMetadataElement);
-        break;
-      }
-    }
-    if (!exists || modified) {
-      final File manifestOutput = _outputDir
-        .childDirectory('app')
-        .childDirectory('src')
-        .childDirectory('main')
-        .childFile('AndroidManifest.xml');
-      ErrorHandlingFileSystem.deleteIfExists(manifestOutput);
-      manifestOutput.createSync(recursive: true);
-      manifestOutput.writeAsStringSync(document.toXmlString(pretty: true), flush: true);
-      _modifiedFiles.add(manifestOutput.path);
-      return false;
-    }
-    return true;
-  }
-
   /// Checks if the base module `app`'s `strings.xml` contain string
   /// resources for each component's name.
   ///
@@ -284,6 +107,7 @@ class DeferredComponentsSetupValidator {
   /// `Name` as a suffix, and the text contents should be the component name.
   bool checkAndroidResourcesStrings(List<DeferredComponent> components) {
     final Directory androidDir = env.projectDir.childDirectory('android');
+    inputs.add(env.projectDir.childFile('pubspec.yaml'));
 
     // Add component name mapping to strings.xml
     final File stringRes = androidDir
@@ -293,8 +117,8 @@ class DeferredComponentsSetupValidator {
       .childDirectory('res')
       .childDirectory('values')
       .childFile('strings.xml');
-    _inputs.add(stringRes);
-    final File stringResOutput = _outputDir
+    inputs.add(stringRes);
+    final File stringResOutput = outputDir
       .childDirectory('app')
       .childDirectory('src')
       .childDirectory('main')
@@ -302,6 +126,9 @@ class DeferredComponentsSetupValidator {
       .childDirectory('values')
       .childFile('strings.xml');
     ErrorHandlingFileSystem.deleteIfExists(stringResOutput);
+    if (components == null || components.isEmpty) {
+      return true;
+    }
     final Map<String, String> requiredEntriesMap  = <String, String>{};
     for (final DeferredComponent component in components) {
       requiredEntriesMap['${component.name}Name'] = component.name;
@@ -312,7 +139,7 @@ class DeferredComponentsSetupValidator {
       try {
         document = XmlDocument.parse(stringRes.readAsStringSync());
       } on XmlParserException {
-        _invalidFiles[stringRes.path] = 'Error parsing $stringRes '
+        invalidFiles[stringRes.path] = 'Error parsing $stringRes '
         'Please ensure that the strings.xml is a valid XML document and '
         'try again.';
         return false;
@@ -348,7 +175,7 @@ class DeferredComponentsSetupValidator {
       if (modified) {
         stringResOutput.createSync(recursive: true);
         stringResOutput.writeAsStringSync(document.toXmlString(pretty: true));
-        _modifiedFiles.add(stringResOutput.path);
+        modifiedFiles.add(stringResOutput.path);
         return false;
       }
       return true;
@@ -369,321 +196,15 @@ class DeferredComponentsSetupValidator {
 
 ''');
     stringResOutput.writeAsStringSync(buffer.toString(), flush: true, mode: FileMode.append);
-    _generatedFiles.add(stringResOutput.path);
+    generatedFiles.add(stringResOutput.path);
     return false;
   }
 
-  /// Compares the provided loading units against the contents of the
-  /// `deferred_components_golden.yaml` file.
-  ///
-  /// Returns true if a golden exists and all loading units match, and false
-  /// otherwise.
-  ///
-  /// This method will parse the golden file if it exists and compare it to
-  /// the provided generatedLoadingUnits. It will distinguish between newly
-  /// added loading units and no longer existing loading units. If the golden
-  /// file does not exist, then all generatedLoadingUnits will be considered
-  /// new.
-  bool checkAgainstLoadingUnitGolden(
-      List<LoadingUnit> generatedLoadingUnits) {
-    final List<LoadingUnit> goldenLoadingUnits = _parseGolden(env.projectDir.childFile(kDeferredComponentsGoldenFileName));
-    _goldenComparisonResults = <String, dynamic>{};
-    final Set<LoadingUnit> unmatchedLoadingUnits = <LoadingUnit>{};
-    final List<LoadingUnit> newLoadingUnits = <LoadingUnit>[];
-    if (generatedLoadingUnits == null || goldenLoadingUnits == null) {
-      _goldenComparisonResults['new'] = newLoadingUnits;
-      _goldenComparisonResults['missing'] = unmatchedLoadingUnits;
-      _goldenComparisonResults['match'] = false;
-      return false;
-    }
-    _inputs.add(env.projectDir.childFile(kDeferredComponentsGoldenFileName));
-    unmatchedLoadingUnits.addAll(goldenLoadingUnits);
-    final Set<int> addedNewIds = <int>{};
-    for (final LoadingUnit genUnit in generatedLoadingUnits) {
-      bool matched = false;
-      for (final LoadingUnit goldUnit in goldenLoadingUnits) {
-        if (genUnit.equalsIgnoringPath(goldUnit)) {
-          matched = true;
-          unmatchedLoadingUnits.remove(goldUnit);
-          break;
-        }
-      }
-      if (!matched && !addedNewIds.contains(genUnit.id)) {
-        newLoadingUnits.add(genUnit);
-        addedNewIds.add(genUnit.id);
-      }
-    }
-    _goldenComparisonResults['new'] = newLoadingUnits;
-    _goldenComparisonResults['missing'] = unmatchedLoadingUnits;
-    _goldenComparisonResults['match'] = newLoadingUnits.isEmpty && unmatchedLoadingUnits.isEmpty;
-    return _goldenComparisonResults['match'] as bool;
-  }
-
-  List<LoadingUnit> _parseGolden(File goldenFile) {
-    final List<LoadingUnit> loadingUnits = <LoadingUnit>[];
-    _inputs.add(goldenFile);
-    if (!goldenFile.existsSync()) {
-      return loadingUnits;
-    }
-    final YamlMap data = loadYaml(goldenFile.readAsStringSync()) as YamlMap;
-    // validate yaml format.
-    if (!data.containsKey('loading-units')) {
-      _invalidFiles[goldenFile.path] = 'Invalid golden yaml file, \'loading-units\' '
-                                       'entry did not exist.';
-      return loadingUnits;
-    } else {
-      if (data['loading-units'] is! YamlList && data['loading-units'] != null) {
-        _invalidFiles[goldenFile.path] = 'Invalid golden yaml file, \'loading-units\' '
-                                         'is not a list.';
-        return loadingUnits;
-      }
-      if (data['loading-units'] != null) {
-        for (final dynamic loadingUnitData in data['loading-units']) {
-          if (loadingUnitData is! YamlMap) {
-            _invalidFiles[goldenFile.path] = 'Invalid golden yaml file, \'loading-units\' '
-                                             'is not a list of maps.';
-            return loadingUnits;
-          }
-          final YamlMap loadingUnitDataMap = loadingUnitData as YamlMap;
-          if (loadingUnitDataMap['id'] == null) {
-            _invalidFiles[goldenFile.path] = 'Invalid golden yaml file, all '
-                                             'loading units must have an \'id\'';
-            return loadingUnits;
-          }
-          if (loadingUnitDataMap['libraries'] != null) {
-            if (loadingUnitDataMap['libraries'] is! YamlList) {
-              _invalidFiles[goldenFile.path] = 'Invalid golden yaml file, \'libraries\' '
-                                               'is not a list.';
-              return loadingUnits;
-            }
-            for (final dynamic node in loadingUnitDataMap['libraries'] as YamlList) {
-              if (node is! String) {
-                _invalidFiles[goldenFile.path] = 'Invalid golden yaml file, \'libraries\' '
-                                                 'is not a list of strings.';
-                return loadingUnits;
-              }
-            }
-          }
-        }
-      }
-    }
-
-    // Parse out validated yaml.
-    if (data.containsKey('loading-units')) {
-      if (data['loading-units'] != null) {
-        for (final dynamic loadingUnitData in data['loading-units']) {
-          final YamlMap loadingUnitDataMap = loadingUnitData as YamlMap;
-          final List<String> libraries = <String>[];
-          if (loadingUnitDataMap['libraries'] != null) {
-            for (final dynamic node in loadingUnitDataMap['libraries'] as YamlList) {
-              libraries.add(node as String);
-            }
-          }
-          loadingUnits.add(
-              LoadingUnit(
-                id: loadingUnitDataMap['id'] as int,
-                path: null,
-                libraries: libraries,
-              ));
-        }
-      }
-    }
-    return loadingUnits;
-  }
-
-  /// Writes the provided generatedLoadingUnits as `deferred_components_golden.yaml`
-  ///
-  /// This golden file is used to detect any changes in the loading units
-  /// produced by gen_snapshot. Running [checkAgainstLoadingUnitGolden] with a
-  /// mismatching or missing golden will result in a failed validation. This
-  /// prevents unexpected changes in loading units causing misconfigured
-  /// deferred components.
-  void writeGolden(List<LoadingUnit> generatedLoadingUnits) {
-    generatedLoadingUnits ??= <LoadingUnit>[];
-    final File goldenFile = env.projectDir.childFile(kDeferredComponentsGoldenFileName);
-    _outputs.add(goldenFile);
-    ErrorHandlingFileSystem.deleteIfExists(goldenFile);
-    goldenFile.createSync(recursive: true);
-
-    final StringBuffer buffer = StringBuffer();
-    buffer.write('''
-# ===============================================================================
-# The contents of this file are automatically generated and it is not recommended
-# to modify this file manually.
-# ===============================================================================
-#
-# In order to prevent unexpected splitting of deferred apps, this golden
-# file records the last generated set of loading units. It only possible
-# to obtain the final configuration of loading units after compilation is
-# complete. This means improperly setup imports can only be detected after
-# compilation.
-#
-# This golden file allows the build tool to detect any changes in the generated
-# loading units. During the next build attempt, loading units in this file are
-# compared against the newly generated loading units to check for any new or
-# removed loading units. In the case where loading units do not match, the build
-# will fail and ask the developer to verify that the `deferred-components`
-# configuration in `pubspec.yaml` is correct. Developers should make any necessary
-# changes to integrate new and changed loading units or remove no longer existing
-# loading units from the configuration. The build command should then be
-# re-run to continue the build process.
-#
-# Sometimes, changes to the generated loading units may be unintentional. If
-# the list of loading units in this golden is not what is expected, the app's
-# deferred imports should be reviewed. Third party plugins and packages may
-# also introduce deferred imports that result in unexpected loading units.
-loading-units:
-''');
-    final Set<int> usedIds = <int>{};
-    for (final LoadingUnit unit in generatedLoadingUnits) {
-      if (usedIds.contains(unit.id)) {
-        continue;
-      }
-      buffer.write('  - id: ${unit.id}\n');
-      if (unit.libraries != null && unit.libraries.isNotEmpty) {
-        buffer.write('    libraries:\n');
-        for (final String lib in unit.libraries) {
-          buffer.write('      - $lib\n');
-        }
-      }
-      usedIds.add(unit.id);
-    }
-    goldenFile.writeAsStringSync(buffer.toString(), flush: true);
-  }
-
   /// Deletes all files inside of the validator's output directory.
   void clearOutputDir() {
-    final Directory dir = env.projectDir.childDirectory('build').childDirectory(kDeferredComponentsTempDirectory);
+    final Directory dir = env.projectDir.childDirectory('build').childDirectory(DeferredComponentsValidator.kDeferredComponentsTempDirectory);
     ErrorHandlingFileSystem.deleteIfExists(dir, recursive: true);
   }
-
-  /// Handles the results of all executed checks by calling [displayResults] and
-  /// [attemptToolExit].
-  ///
-  /// This should be called after all desired checks and tasks are executed.
-  void handleResults() {
-    displayResults();
-    attemptToolExit();
-  }
-
-  static const String _thickDivider = '=================================================================================';
-  static const String _thinDivider = '---------------------------------------------------------------------------------';
-
-  /// Displays the results of this validator's executed checks and tasks in a
-  /// human readable format.
-  ///
-  /// All checks that are desired should be run before calling this method.
-  void displayResults() {
-    if (changesNeeded) {
-      env.logger.printStatus(_thickDivider);
-      env.logger.printStatus(_title, indent: (_thickDivider.length - _title.length) ~/ 2, emphasis: true);
-      env.logger.printStatus(_thickDivider);
-      // Log any file reading/existence errors.
-      if (_invalidFiles.isNotEmpty) {
-        env.logger.printStatus('Errors checking the following files:\n', emphasis: true);
-        for (final String key in _invalidFiles.keys) {
-          env.logger.printStatus('  - $key: ${_invalidFiles[key]}\n');
-        }
-      }
-      // Log diff file contents, with color highlighting
-      if (_diffLines != null && _diffLines.isNotEmpty) {
-        env.logger.printStatus('Diff between `android` and expected files:', emphasis: true);
-        env.logger.printStatus('');
-        for (final String line in _diffLines) {
-          // We only care about diffs in files that have
-          // counterparts.
-          if (line.startsWith('Only in android')) {
-            continue;
-          }
-          TerminalColor color = TerminalColor.grey;
-          if (line.startsWith('+')) {
-            color = TerminalColor.green;
-          } else if (line.startsWith('-')) {
-            color = TerminalColor.red;
-          }
-          env.logger.printStatus(line, color: color);
-        }
-        env.logger.printStatus('');
-      }
-      // Log any newly generated and modified files.
-      if (_generatedFiles.isNotEmpty) {
-        env.logger.printStatus('Newly generated android files:', emphasis: true);
-        for (final String filePath in _generatedFiles) {
-          final String shortenedPath = filePath.substring(env.projectDir.parent.path.length + 1);
-          env.logger.printStatus('  - $shortenedPath', color: TerminalColor.grey);
-        }
-        env.logger.printStatus('');
-      }
-      if (_modifiedFiles.isNotEmpty) {
-        env.logger.printStatus('Modified android files:', emphasis: true);
-        for (final String filePath in _modifiedFiles) {
-          final String shortenedPath = filePath.substring(env.projectDir.parent.path.length + 1);
-          env.logger.printStatus('  - $shortenedPath', color: TerminalColor.grey);
-        }
-        env.logger.printStatus('');
-      }
-      if (_generatedFiles.isNotEmpty || _modifiedFiles.isNotEmpty) {
-        env.logger.printStatus('''
-The above files have been placed into `build/$kDeferredComponentsTempDirectory`,
-a temporary directory. The files should be reviewed and moved into the project's
-`android` directory.''');
-        if (_diffLines != null && _diffLines.isNotEmpty && !globals.platform.isWindows) {
-          env.logger.printStatus(r'''
-
-The recommended changes can be quickly applied by running:
-
-  $ patch -p0 < build/setup_deferred_components.diff
-''');
-        }
-        env.logger.printStatus('$_thinDivider\n');
-      }
-      // Log loading unit golden changes, if any.
-      if (_goldenComparisonResults != null) {
-        if ((_goldenComparisonResults['new'] as List<LoadingUnit>).isNotEmpty) {
-          env.logger.printStatus('New loading units were found:', emphasis: true);
-          for (final LoadingUnit unit in _goldenComparisonResults['new'] as List<LoadingUnit>) {
-            env.logger.printStatus(unit.toString(), color: TerminalColor.grey, indent: 2);
-          }
-          env.logger.printStatus('');
-        }
-        if ((_goldenComparisonResults['missing'] as Set<LoadingUnit>).isNotEmpty) {
-          env.logger.printStatus('Previously existing loading units no longer exist:', emphasis: true);
-          for (final LoadingUnit unit in _goldenComparisonResults['missing'] as Set<LoadingUnit>) {
-            env.logger.printStatus(unit.toString(), color: TerminalColor.grey, indent: 2);
-          }
-          env.logger.printStatus('');
-        }
-        if (_goldenComparisonResults['match'] as bool) {
-          env.logger.printStatus('No change in generated loading units.\n');
-        } else {
-          env.logger.printStatus('''
-It is recommended to verify that the changed loading units are expected
-and to update the `deferred-components` section in `pubspec.yaml` to
-incorporate any changes. The full list of generated loading units can be
-referenced in the $kDeferredComponentsGoldenFileName file located alongside
-pubspec.yaml.
-
-This loading unit check will not fail again on the next build attempt
-if no additional changes to the loading units are detected.
-$_thinDivider\n''');
-        }
-      }
-      // TODO(garyq): Add link to web tutorial/guide once it is written.
-      env.logger.printStatus('''
-Setup verification can be skipped by passing the `--no-verify-deferred-components`
-flag, however, doing so may put your app at risk of not functioning even if the
-build is successful.
-$_thickDivider''');
-      return;
-    }
-    env.logger.printStatus('$_title passed.');
-  }
-
-  void attemptToolExit() {
-    if (exitOnFail && changesNeeded) {
-      throwToolExit('Setup for deferred components incomplete. See recommended actions.', exitCode: 1);
-    }
-  }
 }
 
 // Handles a single deferred component's android dynamic feature module

packages/flutter_tools/lib/src/android/deferred_components_validator.dart

+// 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.
+
+// @dart = 2.8
+
+import '../base/common.dart';
+import '../base/deferred_component.dart';
+import '../base/file_system.dart';
+import '../base/terminal.dart';
+import '../build_system/build_system.dart';
+import '../globals.dart' as globals;
+
+/// A class to configure and run deferred component setup verification checks
+/// and tasks.
+///
+/// Once constructed, checks and tasks can be executed by calling the respective
+/// methods. The results of the checks are stored internally and can be
+/// displayed to the user by calling [displayResults].
+///
+/// The results of each check are handled internally as they are not meant to
+/// be run isolated.
+abstract class DeferredComponentsValidator {
+  DeferredComponentsValidator(this.env, {
+    this.exitOnFail = true,
+    String title,
+  }) : outputDir = env.projectDir
+        .childDirectory('build')
+        .childDirectory(kDeferredComponentsTempDirectory),
+      inputs = <File>[],
+      outputs = <File>[],
+      title = title ?? 'Deferred components setup verification',
+      generatedFiles = <String>[],
+      modifiedFiles = <String>[],
+      invalidFiles = <String, String>{},
+      diffLines = <String>[];
+  /// The build environment that should be used to find the input files to run
+  /// checks against.
+  ///
+  /// The checks in this class are meant to be used as part of a build process,
+  /// so an environment should be available.
+  final Environment env;
+
+  /// When true, failed checks and tasks will result in [attemptToolExit]
+  /// triggering [throwToolExit].
+  final bool exitOnFail;
+
+  /// The name of the golden file that tracks the latest loading units
+  /// generated.
+  static const String kLoadingUnitsCacheFileName = 'deferred_components_loading_units.yaml';
+  /// The directory in the build folder to generate missing/modified files into.
+  static const String kDeferredComponentsTempDirectory = 'android_deferred_components_setup_files';
+
+  /// The title printed at the top of the results of [displayResults]
+  final String title;
+
+  /// The temporary directory that the validator writes recommended files into.
+  final Directory outputDir;
+
+  /// Files that were newly generated by this validator.
+  final List<String> generatedFiles;
+
+  /// Existing files that were modified by this validator.
+  final List<String> modifiedFiles;
+
+  /// Files that were invalid and unable to be checked. These files are input
+  /// files that the validator tries to read rather than output files the
+  /// validator generates. The key is the file name and the value is the message
+  /// or reason it was invalid.
+  final Map<String, String> invalidFiles;
+
+  // TODO(garyq): implement the diff task.
+  /// Output of the diff task.
+  final List<String> diffLines;
+
+  /// Tracks the new and missing loading units.
+  Map<String, dynamic> loadingUnitComparisonResults;
+
+  /// All files read by the validator.
+  final List<File> inputs;
+  /// All files output by the validator.
+  final List<File> outputs;
+
+  /// Returns true if there were any recommended changes that should
+  /// be applied.
+  ///
+  /// Retuns false if no problems or recommendations were detected.
+  ///
+  /// If no checks are run, then this will default to false and will remain so
+  /// until a failing check finishes running.
+  bool get changesNeeded => generatedFiles.isNotEmpty
+    || modifiedFiles.isNotEmpty
+    || invalidFiles.isNotEmpty
+    || (loadingUnitComparisonResults != null && !(loadingUnitComparisonResults['match'] as bool));
+
+  /// Handles the results of all executed checks by calling [displayResults] and
+  /// [attemptToolExit].
+  ///
+  /// This should be called after all desired checks and tasks are executed.
+  void handleResults() {
+    displayResults();
+    attemptToolExit();
+  }
+
+  static const String _thickDivider = '=================================================================================';
+  static const String _thinDivider = '---------------------------------------------------------------------------------';
+
+  /// Displays the results of this validator's executed checks and tasks in a
+  /// human readable format.
+  ///
+  /// All checks that are desired should be run before calling this method.
+  void displayResults() {
+    if (changesNeeded) {
+      env.logger.printStatus(_thickDivider);
+      env.logger.printStatus(title, indent: (_thickDivider.length - title.length) ~/ 2, emphasis: true);
+      env.logger.printStatus(_thickDivider);
+      // Log any file reading/existence errors.
+      if (invalidFiles.isNotEmpty) {
+        env.logger.printStatus('Errors checking the following files:\n', emphasis: true);
+        for (final String key in invalidFiles.keys) {
+          env.logger.printStatus('  - $key: ${invalidFiles[key]}\n');
+        }
+      }
+      // Log diff file contents, with color highlighting
+      if (diffLines != null && diffLines.isNotEmpty) {
+        env.logger.printStatus('Diff between `android` and expected files:', emphasis: true);
+        env.logger.printStatus('');
+        for (final String line in diffLines) {
+          // We only care about diffs in files that have
+          // counterparts.
+          if (line.startsWith('Only in android')) {
+            continue;
+          }
+          TerminalColor color = TerminalColor.grey;
+          if (line.startsWith('+')) {
+            color = TerminalColor.green;
+          } else if (line.startsWith('-')) {
+            color = TerminalColor.red;
+          }
+          env.logger.printStatus(line, color: color);
+        }
+        env.logger.printStatus('');
+      }
+      // Log any newly generated and modified files.
+      if (generatedFiles.isNotEmpty) {
+        env.logger.printStatus('Newly generated android files:', emphasis: true);
+        for (final String filePath in generatedFiles) {
+          final String shortenedPath = filePath.substring(env.projectDir.parent.path.length + 1);
+          env.logger.printStatus('  - $shortenedPath', color: TerminalColor.grey);
+        }
+        env.logger.printStatus('');
+      }
+      if (modifiedFiles.isNotEmpty) {
+        env.logger.printStatus('Modified android files:', emphasis: true);
+        for (final String filePath in modifiedFiles) {
+          final String shortenedPath = filePath.substring(env.projectDir.parent.path.length + 1);
+          env.logger.printStatus('  - $shortenedPath', color: TerminalColor.grey);
+        }
+        env.logger.printStatus('');
+      }
+      if (generatedFiles.isNotEmpty || modifiedFiles.isNotEmpty) {
+        env.logger.printStatus('''
+The above files have been placed into `build/$kDeferredComponentsTempDirectory`,
+a temporary directory. The files should be reviewed and moved into the project's
+`android` directory.''');
+        if (diffLines != null && diffLines.isNotEmpty && !globals.platform.isWindows) {
+          env.logger.printStatus(r'''
+
+The recommended changes can be quickly applied by running:
+
+  $ patch -p0 < build/setup_deferred_components.diff
+''');
+        }
+        env.logger.printStatus('$_thinDivider\n');
+      }
+      // Log loading unit golden changes, if any.
+      if (loadingUnitComparisonResults != null) {
+        if ((loadingUnitComparisonResults['new'] as List<LoadingUnit>).isNotEmpty) {
+          env.logger.printStatus('New loading units were found:', emphasis: true);
+          for (final LoadingUnit unit in loadingUnitComparisonResults['new'] as List<LoadingUnit>) {
+            env.logger.printStatus(unit.toString(), color: TerminalColor.grey, indent: 2);
+          }
+          env.logger.printStatus('');
+        }
+        if ((loadingUnitComparisonResults['missing'] as Set<LoadingUnit>).isNotEmpty) {
+          env.logger.printStatus('Previously existing loading units no longer exist:', emphasis: true);
+          for (final LoadingUnit unit in loadingUnitComparisonResults['missing'] as Set<LoadingUnit>) {
+            env.logger.printStatus(unit.toString(), color: TerminalColor.grey, indent: 2);
+          }
+          env.logger.printStatus('');
+        }
+        if (loadingUnitComparisonResults['match'] as bool) {
+          env.logger.printStatus('No change in generated loading units.\n');
+        } else {
+          env.logger.printStatus('''
+It is recommended to verify that the changed loading units are expected
+and to update the `deferred-components` section in `pubspec.yaml` to
+incorporate any changes. The full list of generated loading units can be
+referenced in the $kLoadingUnitsCacheFileName file located alongside
+pubspec.yaml.
+
+This loading unit check will not fail again on the next build attempt
+if no additional changes to the loading units are detected.
+$_thinDivider\n''');
+        }
+      }
+      // TODO(garyq): Add link to web tutorial/guide once it is written.
+      env.logger.printStatus('''
+Setup verification can be skipped by passing the `--no-verify-deferred-components`
+flag, however, doing so may put your app at risk of not functioning even if the
+build is successful.
+$_thickDivider''');
+      return;
+    }
+    env.logger.printStatus('$title passed.');
+  }
+
+  void attemptToolExit() {
+    if (exitOnFail && changesNeeded) {
+      throwToolExit('Setup for deferred components incomplete. See recommended actions.', exitCode: 1);
+    }
+  }
+}

packages/flutter_tools/lib/src/build_system/build_system.dart

@@ -250,6 +250,29 @@ abstract class Target {
   }
 }
 
+/// Target that contains multiple other targets.
+///
+/// This target does not do anything in its own [build]
+/// and acts as a wrapper around multiple other targets.
+class CompositeTarget extends Target {
+  CompositeTarget(this.dependencies);
+
+  @override
+  final List<Target> dependencies;
+
+  @override
+  String get name => '_composite';
+
+  @override
+  Future<void> build(Environment environment) async { }
+
+  @override
+  List<Source> get inputs => <Source>[];
+
+  @override
+  List<Source> get outputs => <Source>[];
+}
+
 /// The [Environment] defines several constants for use during the build.
 ///
 /// The environment contains configuration and file paths that are safe to

packages/flutter_tools/lib/src/build_system/targets/deferred_components.dart

+// 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.
+
+// @dart = 2.8
+
+import 'package:meta/meta.dart';
+
+import '../../android/deferred_components_gen_snapshot_validator.dart';
+import '../../base/deferred_component.dart';
+import '../../project.dart';
+import '../build_system.dart';
+import '../depfile.dart';
+
+/// Creates a [DeferredComponentsGenSnapshotValidator], runs the checks, and displays the validator
+/// output to the developer if changes are recommended.
+class DeferredComponentsGenSnapshotValidatorTarget extends Target {
+  /// Create an [AndroidAotDeferredComponentsBundle] implementation for a given [targetPlatform] and [buildMode].
+  DeferredComponentsGenSnapshotValidatorTarget({
+    @required this.dependency,
+    @required this.abis,
+    this.title,
+    this.exitOnFail = true,
+    String name = 'deferred_components_setup_validator',
+  }) : _name = name;
+
+  /// The [AndroidAotDeferredComponentsBundle] derived target instances this rule depends on packed
+  /// as a [CompositeTarget].
+  final CompositeTarget dependency;
+
+  /// The title of the [DeferredComponentsGenSnapshotValidator] that is
+  /// displayed to the developer when logging results.
+  final String title;
+
+  /// Whether to exit the tool if a recommended change is found by the
+  /// [DeferredComponentsGenSnapshotValidator].
+  final bool exitOnFail;
+
+  /// The abis to validate.
+  final List<String> abis;
+
+  @override
+  String get name => _name;
+  final String _name;
+
+  @override
+  List<Source> get inputs => const <Source>[];
+
+  @override
+  List<Source> get outputs => const <Source>[];
+
+  @override
+  List<String> get depfiles => <String>[
+    'flutter_$name.d',
+  ];
+
+  @override
+  List<Target> get dependencies => dependency == null ? <Target>[] : <Target>[dependency];
+
+  @visibleForTesting
+  DeferredComponentsGenSnapshotValidator validator;
+
+  @override
+  Future<void> build(Environment environment) async {
+    final DepfileService depfileService = DepfileService(
+      fileSystem: environment.fileSystem,
+      logger: environment.logger,
+    );
+    validator = DeferredComponentsGenSnapshotValidator(
+      environment,
+      title: title,
+      exitOnFail: exitOnFail,
+    );
+
+    final List<LoadingUnit> generatedLoadingUnits = LoadingUnit.parseGeneratedLoadingUnits(
+        environment.outputDir,
+        environment.logger,
+        abis: abis
+    );
+
+    validator
+      ..checkAppAndroidManifestComponentLoadingUnitMapping(
+          FlutterProject.current().manifest.deferredComponents,
+          generatedLoadingUnits,
+      )
+      ..checkAgainstLoadingUnitsCache(generatedLoadingUnits)
+      ..writeLoadingUnitsCache(generatedLoadingUnits);
+
+    validator.handleResults();
+
+    depfileService.writeToFile(
+      Depfile(validator.inputs, validator.outputs),
+      environment.buildDir.childFile('flutter_$name.d'),
+    );
+  }
+}

packages/flutter_tools/lib/src/commands/assemble.dart

@@ -227,7 +227,7 @@ class AssembleCommand extends FlutterCommand {
   @override
   Future<FlutterCommandResult> runCommand() async {
     final List<Target> targets = createTargets();
-    final Target target = targets.length == 1 ? targets.single : _CompositeTarget(targets);
+    final Target target = targets.length == 1 ? targets.single : CompositeTarget(targets);
     final BuildResult result = await globals.buildSystem.build(
       target,
       createEnvironment(),
@@ -308,22 +308,3 @@ void writePerformanceData(Iterable<PerformanceMeasurement> measurements, File ou
   }
   outFile.writeAsStringSync(json.encode(jsonData));
 }
-
-class _CompositeTarget extends Target {
-  _CompositeTarget(this.dependencies);
-
-  @override
-  final List<Target> dependencies;
-
-  @override
-  String get name => '_composite';
-
-  @override
-  Future<void> build(Environment environment) async { }
-
-  @override
-  List<Source> get inputs => <Source>[];
-
-  @override
-  List<Source> get outputs => <Source>[];
-}

packages/flutter_tools/test/general.shard/android/deferred_components_setup_validator_test.dart → packages/flutter_tools/test/general.shard/android/deferred_components_gen_snapshot_validator_test.dart

@@ -5,7 +5,8 @@
 // @dart = 2.8
 
 import 'package:file/memory.dart';
-import 'package:flutter_tools/src/android/deferred_components_setup_validator.dart';
+import 'package:flutter_tools/src/android/deferred_components_gen_snapshot_validator.dart';
+import 'package:flutter_tools/src/android/deferred_components_validator.dart';
 import 'package:flutter_tools/src/base/deferred_component.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/logger.dart';
@@ -14,7 +15,6 @@ import 'package:flutter_tools/src/build_system/targets/common.dart';
 import 'package:flutter_tools/src/globals.dart' as globals;
 
 import '../../src/common.dart';
-import '../../src/context.dart';
 
 void main() {
   FileSystem fileSystem;
@@ -48,7 +48,7 @@ void main() {
   });
 
   testWithoutContext('No checks passes', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
@@ -58,29 +58,17 @@ void main() {
     expect(logger.statusText, 'test check passed.\n');
   });
 
-  testWithoutContext('clearTempDir passes', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
-      env,
-      exitOnFail: false,
-      title: 'test check',
-    );
-    validator.displayResults();
-    validator.attemptToolExit();
-
-    expect(logger.statusText, 'test check passed.\n');
-  });
-
-  testWithoutContext('writeGolden passes', () async {
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+  testWithoutContext('writeCache passes', () async {
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    validator.writeGolden(
+    validator.writeLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 2, libraries: <String>['lib1']),
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
@@ -91,7 +79,7 @@ void main() {
 
     expect(logger.statusText, 'test check passed.\n');
 
-    final File expectedFile = env.projectDir.childFile('deferred_components_golden.yaml');
+    final File expectedFile = env.projectDir.childFile('deferred_components_loading_units.yaml');
 
     expect(expectedFile.existsSync(), true);
     const String expectedContents =
@@ -108,18 +96,18 @@ loading-units:
     expect(expectedFile.readAsStringSync().contains(expectedContents), true);
   });
 
-  testWithoutContext('loadingUnitGolden identical passes', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache identical passes', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - id: 2
     libraries:
@@ -129,7 +117,7 @@ loading-units:
       - lib2
       - lib3
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 2, libraries: <String>['lib1']),
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
@@ -141,25 +129,25 @@ loading-units:
     expect(logger.statusText, 'test check passed.\n');
   });
 
-  testWithoutContext('loadingUnitGolden finds new loading units', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache finds new loading units', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - id: 3
     libraries:
       - lib2
       - lib3
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 2, libraries: <String>['lib1']),
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
@@ -171,18 +159,18 @@ loading-units:
     expect(logger.statusText.contains('New loading units were found:\n\n  LoadingUnit 2\n    Libraries:\n    - lib1\n'), true);
   });
 
-  testWithoutContext('loadingUnitGolden finds missing loading units', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache finds missing loading units', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - id: 2
     libraries:
@@ -192,7 +180,7 @@ loading-units:
       - lib2
       - lib3
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -203,17 +191,17 @@ loading-units:
     expect(logger.statusText.contains('Previously existing loading units no longer exist:\n\n  LoadingUnit 2\n    Libraries:\n    - lib1\n'), true);
   });
 
-  testWithoutContext('missing golden file counts as all new loading units', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('missing cache file counts as all new loading units', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 2, libraries: <String>['lib1']),
       ],
@@ -224,18 +212,18 @@ loading-units:
     expect(logger.statusText.contains('New loading units were found:\n\n  LoadingUnit 2\n    Libraries:\n    - lib1\n'), true);
   });
 
-  testWithoutContext('loadingUnitGolden validator detects malformed file: missing main entry', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache validator detects malformed file: missing main entry', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units-spelled-wrong:
   - id: 2
     libraries:
@@ -245,7 +233,7 @@ loading-units-spelled-wrong:
       - lib2
       - lib3
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -254,26 +242,26 @@ loading-units-spelled-wrong:
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Errors checking the following files:'), true);
-    expect(logger.statusText.contains('Invalid golden yaml file, \'loading-units\' entry did not exist.'), true);
+    expect(logger.statusText.contains('Invalid loading units yaml file, \'loading-units\' entry did not exist.'), true);
 
     expect(logger.statusText.contains('Previously existing loading units no longer exist:\n\n  LoadingUnit 2\n    Libraries:\n    - lib1\n'), false);
   });
 
-  testWithoutContext('loadingUnitGolden validator detects malformed file: not a list', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache validator detects malformed file: not a list', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units: hello
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -282,26 +270,26 @@ loading-units: hello
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Errors checking the following files:'), true);
-    expect(logger.statusText.contains('Invalid golden yaml file, \'loading-units\' is not a list.'), true);
+    expect(logger.statusText.contains('Invalid loading units yaml file, \'loading-units\' is not a list.'), true);
   });
 
-  testWithoutContext('loadingUnitGolden validator detects malformed file: not a list', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache validator detects malformed file: not a list', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - 2
   - 3
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -310,21 +298,21 @@ loading-units:
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Errors checking the following files:'), true);
-    expect(logger.statusText.contains('Invalid golden yaml file, \'loading-units\' is not a list of maps.'), true);
+    expect(logger.statusText.contains('Invalid loading units yaml file, \'loading-units\' is not a list of maps.'), true);
   });
 
-  testWithoutContext('loadingUnitGolden validator detects malformed file: missing id', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache validator detects malformed file: missing id', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - id: 2
     libraries:
@@ -333,7 +321,7 @@ loading-units:
       - lib2
       - lib3
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -342,21 +330,21 @@ loading-units:
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Errors checking the following files:'), true);
-    expect(logger.statusText.contains('Invalid golden yaml file, all loading units must have an \'id\''), true);
+    expect(logger.statusText.contains('Invalid loading units yaml file, all loading units must have an \'id\''), true);
   });
 
-  testWithoutContext('loadingUnitGolden validator detects malformed file: libraries is list', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache validator detects malformed file: libraries is list', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - id: 2
     libraries:
@@ -364,7 +352,7 @@ loading-units:
   - id: 3
     libraries: hello
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -373,21 +361,21 @@ loading-units:
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Errors checking the following files:'), true);
-    expect(logger.statusText.contains('Invalid golden yaml file, \'libraries\' is not a list.'), true);
+    expect(logger.statusText.contains('Invalid loading units yaml file, \'libraries\' is not a list.'), true);
   });
 
-  testWithoutContext('loadingUnitGolden validator detects malformed file: libraries is list of strings', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache validator detects malformed file: libraries is list of strings', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - id: 2
     libraries:
@@ -397,7 +385,7 @@ loading-units:
       - blah: hello
         blah2: hello2
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -406,21 +394,21 @@ loading-units:
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Errors checking the following files:'), true);
-    expect(logger.statusText.contains('Invalid golden yaml file, \'libraries\' is not a list of strings.'), true);
+    expect(logger.statusText.contains('Invalid loading units yaml file, \'libraries\' is not a list of strings.'), true);
   });
 
-  testWithoutContext('loadingUnitGolden validator detects malformed file: empty libraries allowed', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+  testWithoutContext('loadingUnitCache validator detects malformed file: empty libraries allowed', () async {
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
-    final File goldenFile = env.projectDir.childFile(DeferredComponentsSetupValidator.kDeferredComponentsGoldenFileName);
-    if (goldenFile.existsSync()) {
-      goldenFile.deleteSync();
+    final File cacheFile = env.projectDir.childFile(DeferredComponentsValidator.kLoadingUnitsCacheFileName);
+    if (cacheFile.existsSync()) {
+      cacheFile.deleteSync();
     }
-    goldenFile.createSync(recursive: true);
-    goldenFile.writeAsStringSync('''
+    cacheFile.createSync(recursive: true);
+    cacheFile.writeAsStringSync('''
 loading-units:
   - id: 2
     libraries:
@@ -428,7 +416,7 @@ loading-units:
   - id: 3
     libraries:
 ''', flush: true, mode: FileMode.append);
-    validator.checkAgainstLoadingUnitGolden(
+    validator.checkAgainstLoadingUnitsCache(
       <LoadingUnit>[
         LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
       ],
@@ -439,231 +427,13 @@ loading-units:
     expect(logger.statusText.contains('Errors checking the following files:'), false);
   });
 
-  testUsingContext('androidComponentSetup build.gradle does not exist', () async {
-    final Directory templatesDir = env.flutterRootDir.childDirectory('templates').childDirectory('deferred_component');
-    final File buildGradleTemplate = templatesDir.childFile('build.gradle.tmpl');
-    final File androidManifestTemplate = templatesDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml.tmpl');
-    if (templatesDir.existsSync()) {
-      templatesDir.deleteSync(recursive: true);
-    }
-    buildGradleTemplate.createSync(recursive: true);
-    androidManifestTemplate.createSync(recursive: true);
-    buildGradleTemplate.writeAsStringSync('fake build.gradle template {{componentName}}', flush: true, mode: FileMode.append);
-    androidManifestTemplate.writeAsStringSync('fake AndroidManigest.xml template {{componentName}}', flush: true, mode: FileMode.append);
-
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
-      env,
-      exitOnFail: false,
-      title: 'test check',
-      templatesDir: templatesDir,
-    );
-    final Directory componentDir = env.projectDir.childDirectory('android').childDirectory('component1');
-    final File file = componentDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
-    if (file.existsSync()) {
-      file.deleteSync();
-    }
-    file.createSync(recursive: true);
-    await validator.checkAndroidDynamicFeature(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1'),
-      ],
-    );
-    validator.displayResults();
-    validator.attemptToolExit();
-
-    file.deleteSync();
-    expect(logger.statusText.contains('Newly generated android files:\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/component1/build.gradle\n'), true);
-  });
-
-  testUsingContext('androidComponentSetup AndroidManifest.xml does not exist', () async {
-    final Directory templatesDir = env.flutterRootDir.childDirectory('templates').childDirectory('deferred_component');
-    final File buildGradleTemplate = templatesDir.childFile('build.gradle.tmpl');
-    final File androidManifestTemplate = templatesDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml.tmpl');
-    if (templatesDir.existsSync()) {
-      templatesDir.deleteSync(recursive: true);
-    }
-    buildGradleTemplate.createSync(recursive: true);
-    androidManifestTemplate.createSync(recursive: true);
-    buildGradleTemplate.writeAsStringSync('fake build.gradle template {{componentName}}', flush: true, mode: FileMode.append);
-    androidManifestTemplate.writeAsStringSync('fake AndroidManigest.xml template {{componentName}}', flush: true, mode: FileMode.append);
-
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
-      env,
-      exitOnFail: false,
-      title: 'test check',
-      templatesDir: templatesDir,
-    );
-    final Directory componentDir = env.projectDir.childDirectory('android').childDirectory('component1');
-    final File file = componentDir.childFile('build.gradle');
-    if (file.existsSync()) {
-      file.deleteSync();
-    }
-    file.createSync(recursive: true);
-    await validator.checkAndroidDynamicFeature(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1'),
-      ],
-    );
-    validator.displayResults();
-    validator.attemptToolExit();
-
-    file.deleteSync();
-    expect(logger.statusText.contains('Newly generated android files:\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/component1/src/main/AndroidManifest.xml\n'), true);
-  });
-
-  testUsingContext('androidComponentSetup all files exist passes', () async {
-    final Directory templatesDir = env.flutterRootDir.childDirectory('templates').childDirectory('deferred_component');
-    final File buildGradleTemplate = templatesDir.childFile('build.gradle.tmpl');
-    final File androidManifestTemplate = templatesDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml.tmpl');
-    if (templatesDir.existsSync()) {
-      templatesDir.deleteSync(recursive: true);
-    }
-    buildGradleTemplate.createSync(recursive: true);
-    androidManifestTemplate.createSync(recursive: true);
-    buildGradleTemplate.writeAsStringSync('fake build.gradle template {{componentName}}', flush: true, mode: FileMode.append);
-    androidManifestTemplate.writeAsStringSync('fake AndroidManigest.xml template {{componentName}}', flush: true, mode: FileMode.append);
-
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
-      env,
-      exitOnFail: false,
-      title: 'test check',
-      templatesDir: templatesDir,
-    );
-    final Directory componentDir = env.projectDir.childDirectory('android').childDirectory('component1');
-    final File buildGradle = componentDir.childFile('build.gradle');
-    if (buildGradle.existsSync()) {
-      buildGradle.deleteSync();
-    }
-    buildGradle.createSync(recursive: true);
-    final File manifest = componentDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
-    if (manifest.existsSync()) {
-      manifest.deleteSync();
-    }
-    manifest.createSync(recursive: true);
-    await validator.checkAndroidDynamicFeature(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1'),
-      ],
-    );
-    validator.displayResults();
-    validator.attemptToolExit();
-
-    manifest.deleteSync();
-    buildGradle.deleteSync();
-    expect(logger.statusText, 'test check passed.\n');
-  });
-
-  testWithoutContext('androidStringMapping creates new file', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
-      env,
-      exitOnFail: false,
-      title: 'test check',
-    );
-    final Directory baseModuleDir = env.projectDir.childDirectory('android').childDirectory('app');
-    final File stringRes = baseModuleDir.childDirectory('src').childDirectory('main').childDirectory('res').childDirectory('values').childFile('strings.xml');
-    if (stringRes.existsSync()) {
-      stringRes.deleteSync();
-    }
-    final File manifest = baseModuleDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
-    if (manifest.existsSync()) {
-      manifest.deleteSync();
-    }
-    manifest.createSync(recursive: true);
-    manifest.writeAsStringSync('''
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.example.splitaot">
-    <application
-        android:name="io.flutter.app.FlutterPlayStoreSplitApplication"
-        android:label="splitaot"
-        android:extractNativeLibs="false">
-        <activity
-            android:name=".MainActivity"
-            android:launchMode="singleTop"
-            android:windowSoftInputMode="adjustResize">
-        </activity>
-        <!-- Don't delete the meta-data below.
-             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
-        <meta-data
-            android:name="flutterEmbedding"
-            android:value="2" />
-        <meta-data
-            android:name="io.flutter.embedding.engine.deferredcomponents.DeferredComponentManager.loadingUnitMapping"
-            android:value="invalidmapping" />
-    </application>
-</manifest>
-''', flush: true, mode: FileMode.append);
-    validator.checkAppAndroidManifestComponentLoadingUnitMapping(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1', libraries: <String>['lib2']),
-        DeferredComponent(name: 'component2', libraries: <String>['lib1', 'lib4']),
-      ],
-      <LoadingUnit>[
-        LoadingUnit(id: 2, libraries: <String>['lib1']),
-        LoadingUnit(id: 3, libraries: <String>['lib2', 'lib3']),
-        LoadingUnit(id: 4, libraries: <String>['lib4', 'lib5']),
-      ],
-    );
-    validator.checkAndroidResourcesStrings(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1', libraries: <String>['lib2']),
-        DeferredComponent(name: 'component2', libraries: <String>['lib1', 'lib4']),
-      ],
-    );
-    validator.displayResults();
-    validator.attemptToolExit();
-
-    expect(logger.statusText.contains('Modified android files:\n'), true);
-    expect(logger.statusText.contains('Newly generated android files:\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/AndroidManifest.xml\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/res/values/strings.xml\n'), true);
-
-    final File stringsOutput = env.projectDir
-      .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
-      .childDirectory('app')
-      .childDirectory('src')
-      .childDirectory('main')
-      .childDirectory('res')
-      .childDirectory('values')
-      .childFile('strings.xml');
-    expect(stringsOutput.existsSync(), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component1Name">component1</string>'), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component2Name">component2</string>'), true);
-
-    final File manifestOutput = env.projectDir
-      .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
-      .childDirectory('app')
-      .childDirectory('src')
-      .childDirectory('main')
-      .childFile('AndroidManifest.xml');
-    expect(manifestOutput.existsSync(), true);
-    expect(manifestOutput.readAsStringSync().contains('<meta-data android:name="io.flutter.embedding.engine.deferredcomponents.DeferredComponentManager.loadingUnitMapping" android:value="3:component1,2:component2,4:component2"/>'), true);
-    expect(manifestOutput.readAsStringSync().contains('android:value="invalidmapping"'), false);
-    expect(manifestOutput.readAsStringSync().contains('<!-- Don\'t delete the meta-data below.'), true);
-  });
-
   testWithoutContext('androidStringMapping modifies strings file', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
     final Directory baseModuleDir = env.projectDir.childDirectory('android').childDirectory('app');
-    final File stringRes = baseModuleDir.childDirectory('src').childDirectory('main').childDirectory('res').childDirectory('values').childFile('strings.xml');
-    if (stringRes.existsSync()) {
-      stringRes.deleteSync();
-    }
-    stringRes.createSync(recursive: true);
-    stringRes.writeAsStringSync('''
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <string name="component1Name">component1</string>
-</resources>
-
-''', flush: true, mode: FileMode.append);
     final File manifest = baseModuleDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
     if (manifest.existsSync()) {
       manifest.deleteSync();
@@ -706,35 +476,15 @@ loading-units:
         LoadingUnit(id: 4, libraries: <String>['lib4', 'lib5']),
       ],
     );
-    validator.checkAndroidResourcesStrings(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1', libraries: <String>['lib2']),
-        DeferredComponent(name: 'component2', libraries: <String>['lib1', 'lib4']),
-      ],
-    );
     validator.displayResults();
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Modified android files:\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/AndroidManifest.xml\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/res/values/strings.xml\n'), true);
-
-    final File stringsOutput = env.projectDir
-      .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
-      .childDirectory('app')
-      .childDirectory('src')
-      .childDirectory('main')
-      .childDirectory('res')
-      .childDirectory('values')
-      .childFile('strings.xml');
-    expect(stringsOutput.existsSync(), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component1Name">component1</string>'), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component2Name">component2</string>'), true);
+    expect(logger.statusText.contains('build/${DeferredComponentsValidator.kDeferredComponentsTempDirectory}/app/src/main/AndroidManifest.xml\n'), true);
 
     final File manifestOutput = env.projectDir
       .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
+      .childDirectory(DeferredComponentsValidator.kDeferredComponentsTempDirectory)
       .childDirectory('app')
       .childDirectory('src')
       .childDirectory('main')
@@ -746,24 +496,12 @@ loading-units:
   });
 
   testWithoutContext('androidStringMapping adds mapping when no existing mapping', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
     final Directory baseModuleDir = env.projectDir.childDirectory('android').childDirectory('app');
-    final File stringRes = baseModuleDir.childDirectory('src').childDirectory('main').childDirectory('res').childDirectory('values').childFile('strings.xml');
-    if (stringRes.existsSync()) {
-      stringRes.deleteSync();
-    }
-    stringRes.createSync(recursive: true);
-    stringRes.writeAsStringSync('''
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <string name="component1Name">component1</string>
-</resources>
-
-''', flush: true, mode: FileMode.append);
     final File manifest = baseModuleDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
     if (manifest.existsSync()) {
       manifest.deleteSync();
@@ -800,35 +538,15 @@ loading-units:
         LoadingUnit(id: 4, libraries: <String>['lib4', 'lib5']),
       ],
     );
-    validator.checkAndroidResourcesStrings(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1', libraries: <String>['lib2']),
-        DeferredComponent(name: 'component2', libraries: <String>['lib1', 'lib4']),
-      ],
-    );
     validator.displayResults();
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Modified android files:\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/AndroidManifest.xml\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/res/values/strings.xml\n'), true);
-
-    final File stringsOutput = env.projectDir
-      .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
-      .childDirectory('app')
-      .childDirectory('src')
-      .childDirectory('main')
-      .childDirectory('res')
-      .childDirectory('values')
-      .childFile('strings.xml');
-    expect(stringsOutput.existsSync(), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component1Name">component1</string>'), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component2Name">component2</string>'), true);
+    expect(logger.statusText.contains('build/${DeferredComponentsValidator.kDeferredComponentsTempDirectory}/app/src/main/AndroidManifest.xml\n'), true);
 
     final File manifestOutput = env.projectDir
       .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
+      .childDirectory(DeferredComponentsValidator.kDeferredComponentsTempDirectory)
       .childDirectory('app')
       .childDirectory('src')
       .childDirectory('main')
@@ -840,24 +558,12 @@ loading-units:
 
   // Tests if all of the regexp whitespace detection is working.
   testWithoutContext('androidStringMapping handles whitespace within entry', () async {
-    final DeferredComponentsSetupValidator validator = DeferredComponentsSetupValidator(
+    final DeferredComponentsGenSnapshotValidator validator = DeferredComponentsGenSnapshotValidator(
       env,
       exitOnFail: false,
       title: 'test check',
     );
     final Directory baseModuleDir = env.projectDir.childDirectory('android').childDirectory('app');
-    final File stringRes = baseModuleDir.childDirectory('src').childDirectory('main').childDirectory('res').childDirectory('values').childFile('strings.xml');
-    if (stringRes.existsSync()) {
-      stringRes.deleteSync();
-    }
-    stringRes.createSync(recursive: true);
-    stringRes.writeAsStringSync('''
-<?xml version="1.0" encoding="utf-8"?>
-<resources>
-    <string name="component1Name">component1</string>
-</resources>
-
-''', flush: true, mode: FileMode.append);
     final File manifest = baseModuleDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
     if (manifest.existsSync()) {
       manifest.deleteSync();
@@ -901,35 +607,15 @@ loading-units:
         LoadingUnit(id: 4, libraries: <String>['lib4', 'lib5']),
       ],
     );
-    validator.checkAndroidResourcesStrings(
-      <DeferredComponent>[
-        DeferredComponent(name: 'component1', libraries: <String>['lib2']),
-        DeferredComponent(name: 'component2', libraries: <String>['lib1', 'lib4']),
-      ],
-    );
     validator.displayResults();
     validator.attemptToolExit();
 
     expect(logger.statusText.contains('Modified android files:\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/AndroidManifest.xml\n'), true);
-    expect(logger.statusText.contains('build/${DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory}/app/src/main/res/values/strings.xml\n'), true);
-
-    final File stringsOutput = env.projectDir
-      .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
-      .childDirectory('app')
-      .childDirectory('src')
-      .childDirectory('main')
-      .childDirectory('res')
-      .childDirectory('values')
-      .childFile('strings.xml');
-    expect(stringsOutput.existsSync(), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component1Name">component1</string>'), true);
-    expect(stringsOutput.readAsStringSync().contains('<string name="component2Name">component2</string>'), true);
+    expect(logger.statusText.contains('build/${DeferredComponentsValidator.kDeferredComponentsTempDirectory}/app/src/main/AndroidManifest.xml\n'), true);
 
     final File manifestOutput = env.projectDir
       .childDirectory('build')
-      .childDirectory(DeferredComponentsSetupValidator.kDeferredComponentsTempDirectory)
+      .childDirectory(DeferredComponentsValidator.kDeferredComponentsTempDirectory)
       .childDirectory('app')
       .childDirectory('src')
       .childDirectory('main')

packages/flutter_tools/test/general.shard/android/deferred_components_prebuild_validator_test.dart

+// 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.
+
+// @dart = 2.8
+
+import 'package:file/memory.dart';
+import 'package:flutter_tools/src/android/deferred_components_prebuild_validator.dart';
+import 'package:flutter_tools/src/android/deferred_components_validator.dart';
+import 'package:flutter_tools/src/base/deferred_component.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/base/logger.dart';
+import 'package:flutter_tools/src/build_system/build_system.dart';
+import 'package:flutter_tools/src/build_system/targets/common.dart';
+import 'package:flutter_tools/src/globals.dart' as globals;
+
+import '../../src/common.dart';
+import '../../src/context.dart';
+
+void main() {
+  FileSystem fileSystem;
+  BufferLogger logger;
+  Environment env;
+
+  Environment createEnvironment() {
+    final Map<String, String> defines = <String, String>{ kSplitAot: 'true' };
+    final Environment result = Environment(
+      outputDir: fileSystem.directory('/output'),
+      buildDir: fileSystem.directory('/build'),
+      projectDir: fileSystem.directory('/project'),
+      defines: defines,
+      inputs: <String, String>{},
+      cacheDir: fileSystem.directory('/cache'),
+      flutterRootDir: fileSystem.directory('/flutter_root'),
+      artifacts: globals.artifacts,
+      fileSystem: fileSystem,
+      logger: logger,
+      processManager: globals.processManager,
+      engineVersion: 'invalidEngineVersion',
+      generateDartPluginRegistry: false,
+    );
+    return result;
+  }
+
+  setUp(() {
+    fileSystem = MemoryFileSystem.test();
+    logger = BufferLogger.test();
+    env = createEnvironment();
+  });
+
+  testWithoutContext('No checks passes', () async {
+    final DeferredComponentsPrebuildValidator validator = DeferredComponentsPrebuildValidator(
+      env,
+      exitOnFail: false,
+      title: 'test check',
+    );
+    validator.displayResults();
+    validator.attemptToolExit();
+    expect(logger.statusText, 'test check passed.\n');
+  });
+
+  testWithoutContext('clearTempDir passes', () async {
+    final DeferredComponentsPrebuildValidator validator = DeferredComponentsPrebuildValidator(
+      env,
+      exitOnFail: false,
+      title: 'test check',
+    );
+    validator.displayResults();
+    validator.attemptToolExit();
+
+    expect(logger.statusText, 'test check passed.\n');
+  });
+
+  testUsingContext('androidComponentSetup build.gradle does not exist', () async {
+    final Directory templatesDir = env.flutterRootDir.childDirectory('templates').childDirectory('deferred_component');
+    final File buildGradleTemplate = templatesDir.childFile('build.gradle.tmpl');
+    final File androidManifestTemplate = templatesDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml.tmpl');
+    if (templatesDir.existsSync()) {
+      templatesDir.deleteSync(recursive: true);
+    }
+    buildGradleTemplate.createSync(recursive: true);
+    androidManifestTemplate.createSync(recursive: true);
+    buildGradleTemplate.writeAsStringSync('fake build.gradle template {{componentName}}', flush: true, mode: FileMode.append);
+    androidManifestTemplate.writeAsStringSync('fake AndroidManigest.xml template {{componentName}}', flush: true, mode: FileMode.append);
+
+    final DeferredComponentsPrebuildValidator validator = DeferredComponentsPrebuildValidator(
+      env,
+      exitOnFail: false,
+      title: 'test check',
+      templatesDir: templatesDir,
+    );
+    final Directory componentDir = env.projectDir.childDirectory('android').childDirectory('component1');
+    final File file = componentDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
+    if (file.existsSync()) {
+      file.deleteSync();
+    }
+    file.createSync(recursive: true);
+    await validator.checkAndroidDynamicFeature(
+      <DeferredComponent>[
+        DeferredComponent(name: 'component1'),
+      ],
+    );
+    validator.displayResults();
+    validator.attemptToolExit();
+
+    file.deleteSync();
+    expect(logger.statusText.contains('Newly generated android files:\n'), true);
+    expect(logger.statusText.contains('build/${DeferredComponentsValidator.kDeferredComponentsTempDirectory}/component1/build.gradle\n'), true);
+  });
+
+  testUsingContext('androidComponentSetup AndroidManifest.xml does not exist', () async {
+    final Directory templatesDir = env.flutterRootDir.childDirectory('templates').childDirectory('deferred_component');
+    final File buildGradleTemplate = templatesDir.childFile('build.gradle.tmpl');
+    final File androidManifestTemplate = templatesDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml.tmpl');
+    if (templatesDir.existsSync()) {
+      templatesDir.deleteSync(recursive: true);
+    }
+    buildGradleTemplate.createSync(recursive: true);
+    androidManifestTemplate.createSync(recursive: true);
+    buildGradleTemplate.writeAsStringSync('fake build.gradle template {{componentName}}', flush: true, mode: FileMode.append);
+    androidManifestTemplate.writeAsStringSync('fake AndroidManigest.xml template {{componentName}}', flush: true, mode: FileMode.append);
+
+    final DeferredComponentsPrebuildValidator validator = DeferredComponentsPrebuildValidator(
+      env,
+      exitOnFail: false,
+      title: 'test check',
+      templatesDir: templatesDir,
+    );
+    final Directory componentDir = env.projectDir.childDirectory('android').childDirectory('component1');
+    final File file = componentDir.childFile('build.gradle');
+    if (file.existsSync()) {
+      file.deleteSync();
+    }
+    file.createSync(recursive: true);
+    await validator.checkAndroidDynamicFeature(
+      <DeferredComponent>[
+        DeferredComponent(name: 'component1'),
+      ],
+    );
+    validator.displayResults();
+    validator.attemptToolExit();
+
+    file.deleteSync();
+    expect(logger.statusText.contains('Newly generated android files:\n'), true);
+    expect(logger.statusText.contains('build/${DeferredComponentsValidator.kDeferredComponentsTempDirectory}/component1/src/main/AndroidManifest.xml\n'), true);
+  });
+
+  testUsingContext('androidComponentSetup all files exist passes', () async {
+    final Directory templatesDir = env.flutterRootDir.childDirectory('templates').childDirectory('deferred_component');
+    final File buildGradleTemplate = templatesDir.childFile('build.gradle.tmpl');
+    final File androidManifestTemplate = templatesDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml.tmpl');
+    if (templatesDir.existsSync()) {
+      templatesDir.deleteSync(recursive: true);
+    }
+    buildGradleTemplate.createSync(recursive: true);
+    androidManifestTemplate.createSync(recursive: true);
+    buildGradleTemplate.writeAsStringSync('fake build.gradle template {{componentName}}', flush: true, mode: FileMode.append);
+    androidManifestTemplate.writeAsStringSync('fake AndroidManigest.xml template {{componentName}}', flush: true, mode: FileMode.append);
+
+    final DeferredComponentsPrebuildValidator validator = DeferredComponentsPrebuildValidator(
+      env,
+      exitOnFail: false,
+      title: 'test check',
+      templatesDir: templatesDir,
+    );
+    final Directory componentDir = env.projectDir.childDirectory('android').childDirectory('component1');
+    final File buildGradle = componentDir.childFile('build.gradle');
+    if (buildGradle.existsSync()) {
+      buildGradle.deleteSync();
+    }
+    buildGradle.createSync(recursive: true);
+    final File manifest = componentDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
+    if (manifest.existsSync()) {
+      manifest.deleteSync();
+    }
+    manifest.createSync(recursive: true);
+    await validator.checkAndroidDynamicFeature(
+      <DeferredComponent>[
+        DeferredComponent(name: 'component1'),
+      ],
+    );
+    validator.displayResults();
+    validator.attemptToolExit();
+
+    manifest.deleteSync();
+    buildGradle.deleteSync();
+    expect(logger.statusText, 'test check passed.\n');
+  });
+
+  testWithoutContext('androidStringMapping creates new file', () async {
+    final DeferredComponentsPrebuildValidator validator = DeferredComponentsPrebuildValidator(
+      env,
+      exitOnFail: false,
+      title: 'test check',
+    );
+    final Directory baseModuleDir = env.projectDir.childDirectory('android').childDirectory('app');
+    final File stringRes = baseModuleDir.childDirectory('src').childDirectory('main').childDirectory('res').childDirectory('values').childFile('strings.xml');
+    if (stringRes.existsSync()) {
+      stringRes.deleteSync();
+    }
+    final File manifest = baseModuleDir.childDirectory('src').childDirectory('main').childFile('AndroidManifest.xml');
+    if (manifest.existsSync()) {
+      manifest.deleteSync();
+    }
+    manifest.createSync(recursive: true);
+    manifest.writeAsStringSync('''
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.splitaot">
+    <application
+        android:name="io.flutter.app.FlutterPlayStoreSplitApplication"
+        android:label="splitaot"
+        android:extractNativeLibs="false">
+        <activity
+            android:name=".MainActivity"
+            android:launchMode="singleTop"
+            android:windowSoftInputMode="adjustResize">
+        </activity>
+        <!-- Don't delete the meta-data below.
+             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
+        <meta-data
+            android:name="flutterEmbedding"
+            android:value="2" />
+        <meta-data
+            android:name="io.flutter.embedding.engine.deferredcomponents.DeferredComponentManager.loadingUnitMapping"
+            android:value="invalidmapping" />
+    </application>
+</manifest>
+''', flush: true, mode: FileMode.append);
+    validator.checkAndroidResourcesStrings(
+      <DeferredComponent>[
+        DeferredComponent(name: 'component1', libraries: <String>['lib2']),
+        DeferredComponent(name: 'component2', libraries: <String>['lib1', 'lib4']),
+      ],
+    );
+    validator.displayResults();
+    validator.attemptToolExit();
+
+    expect(logger.statusText.contains('Modified android files:\n'), false);
+    expect(logger.statusText.contains('Newly generated android files:\n'), true);
+    expect(logger.statusText.contains('build/${DeferredComponentsValidator.kDeferredComponentsTempDirectory}/app/src/main/res/values/strings.xml\n'), true);
+
+    final File stringsOutput = env.projectDir
+      .childDirectory('build')
+      .childDirectory(DeferredComponentsValidator.kDeferredComponentsTempDirectory)
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childDirectory('res')
+      .childDirectory('values')
+      .childFile('strings.xml');
+    expect(stringsOutput.existsSync(), true);
+    expect(stringsOutput.readAsStringSync().contains('<string name="component1Name">component1</string>'), true);
+    expect(stringsOutput.readAsStringSync().contains('<string name="component2Name">component2</string>'), true);
+  });
+
+  testWithoutContext('androidStringMapping modifies strings file', () async {
+    final DeferredComponentsPrebuildValidator validator = DeferredComponentsPrebuildValidator(
+      env,
+      exitOnFail: false,
+      title: 'test check',
+    );
+    final Directory baseModuleDir = env.projectDir.childDirectory('android').childDirectory('app');
+    final File stringRes = baseModuleDir.childDirectory('src').childDirectory('main').childDirectory('res').childDirectory('values').childFile('strings.xml');
+    if (stringRes.existsSync()) {
+      stringRes.deleteSync();
+    }
+    stringRes.createSync(recursive: true);
+    stringRes.writeAsStringSync('''
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="component1Name">component1</string>
+</resources>
+
+''', flush: true, mode: FileMode.append);
+    validator.checkAndroidResourcesStrings(
+      <DeferredComponent>[
+        DeferredComponent(name: 'component1', libraries: <String>['lib2']),
+        DeferredComponent(name: 'component2', libraries: <String>['lib1', 'lib4']),
+      ],
+    );
+    validator.displayResults();
+    validator.attemptToolExit();
+
+    expect(logger.statusText.contains('Newly generated android files:\n'), false);
+    expect(logger.statusText.contains('Modified android files:\n'), true);
+    expect(logger.statusText.contains('build/${DeferredComponentsValidator.kDeferredComponentsTempDirectory}/app/src/main/res/values/strings.xml\n'), true);
+
+    final File stringsOutput = env.projectDir
+      .childDirectory('build')
+      .childDirectory(DeferredComponentsValidator.kDeferredComponentsTempDirectory)
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childDirectory('res')
+      .childDirectory('values')
+      .childFile('strings.xml');
+    expect(stringsOutput.existsSync(), true);
+    expect(stringsOutput.readAsStringSync().contains('<string name="component1Name">component1</string>'), true);
+    expect(stringsOutput.readAsStringSync().contains('<string name="component2Name">component2</string>'), true);
+  });
+}

packages/flutter_tools/test/general.shard/build_system/targets/deferred_components_test.dart

+// 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.
+
+// @dart = 2.8
+
+import 'package:file/memory.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/base/logger.dart';
+import 'package:flutter_tools/src/build_info.dart';
+import 'package:flutter_tools/src/build_system/build_system.dart';
+import 'package:flutter_tools/src/build_system/targets/deferred_components.dart';
+import 'package:flutter_tools/src/build_system/targets/android.dart';
+import 'package:flutter_tools/src/build_system/targets/common.dart';
+
+import '../../../src/common.dart';
+import '../../../src/context.dart';
+
+// These tests perform a simple check to verify if the check/task was executed at all.
+// Detailed per-check tests are in android/deferred_components_setup_validator_test.dart.
+void main() {
+  FileSystem fileSystem;
+  BufferLogger logger;
+
+  setUp(() {
+    logger = BufferLogger.test();
+    fileSystem = MemoryFileSystem.test();
+  });
+
+  testUsingContext('checkAppAndroidManifestComponentLoadingUnitMapping checks runs', () async {
+    final Environment environment = Environment.test(
+      fileSystem.currentDirectory,
+      outputDir: fileSystem.directory('out')..createSync(),
+      buildDir: fileSystem.directory('build')..createSync(),
+      projectDir: fileSystem.directory('project')..createSync(),
+      defines: <String, String>{
+        kSplitAot: 'true',
+      },
+      artifacts: null,
+      processManager: null,
+      fileSystem: fileSystem,
+      logger: logger,
+    );
+    environment.buildDir.createSync(recursive: true);
+    const AndroidAot androidAot = AndroidAot(TargetPlatform.android_arm64, BuildMode.release);
+    const AndroidAotBundle androidAotBundle = AndroidAotBundle(androidAot);
+    final CompositeTarget androidDefBundle = CompositeTarget(<Target>[androidAotBundle]);
+    final CompositeTarget compositeTarget = CompositeTarget(<Target>[androidDefBundle]);
+    final DeferredComponentsGenSnapshotValidatorTarget validatorTarget = DeferredComponentsGenSnapshotValidatorTarget(
+      dependency: compositeTarget,
+      abis: <String>['arm64-v8a'],
+      title: 'test checks',
+      exitOnFail: false,
+    );
+
+    await validatorTarget.build(environment);
+
+    // We check the inputs to determine if the task was executed.
+    expect(validatorTarget.validator.inputs.length, 3);
+    expect(validatorTarget.validator.inputs[0].path, 'project/pubspec.yaml');
+    expect(validatorTarget.validator.inputs[1].path, 'project/android/app/src/main/AndroidManifest.xml');
+  });
+
+  testUsingContext('checkAgainstLoadingUnitsCache checks runs', () async {
+    final Environment environment = Environment.test(
+      fileSystem.currentDirectory,
+      outputDir: fileSystem.directory('out')..createSync(),
+      buildDir: fileSystem.directory('build')..createSync(),
+      projectDir: fileSystem.directory('project')..createSync(),
+      defines: <String, String>{
+        kSplitAot: 'true',
+      },
+      artifacts: null,
+      processManager: null,
+      fileSystem: fileSystem,
+      logger: logger,
+    );
+    environment.buildDir.createSync(recursive: true);
+    const AndroidAot androidAot = AndroidAot(TargetPlatform.android_arm64, BuildMode.release);
+    const AndroidAotBundle androidAotBundle = AndroidAotBundle(androidAot);
+    final CompositeTarget androidDefBundle = CompositeTarget(<Target>[androidAotBundle]);
+    final CompositeTarget compositeTarget = CompositeTarget(<Target>[androidDefBundle]);
+    final DeferredComponentsGenSnapshotValidatorTarget validatorTarget = DeferredComponentsGenSnapshotValidatorTarget(
+      dependency: compositeTarget,
+      abis: <String>['arm64-v8a'],
+      title: 'test checks',
+      exitOnFail: false,
+    );
+
+    await validatorTarget.build(environment);
+
+    // We check the inputs to determine if the task was executed.
+    expect(validatorTarget.validator.inputs.length, 3);
+    expect(validatorTarget.validator.inputs[2].path, 'project/deferred_components_loading_units.yaml');
+  });
+
+  testUsingContext('writeLoadingUnitsCache task runs', () async {
+    final Environment environment = Environment.test(
+      fileSystem.currentDirectory,
+      outputDir: fileSystem.directory('out')..createSync(),
+      buildDir: fileSystem.directory('build')..createSync(),
+      projectDir: fileSystem.directory('project')..createSync(),
+      defines: <String, String>{
+        kSplitAot: 'true',
+      },
+      artifacts: null,
+      processManager: null,
+      fileSystem: fileSystem,
+      logger: logger,
+    );
+    environment.buildDir.createSync(recursive: true);
+    const AndroidAot androidAot = AndroidAot(TargetPlatform.android_arm64, BuildMode.release);
+    const AndroidAotBundle androidAotBundle = AndroidAotBundle(androidAot);
+    final CompositeTarget androidDefBundle = CompositeTarget(<Target>[androidAotBundle]);
+    final CompositeTarget compositeTarget = CompositeTarget(<Target>[androidDefBundle]);
+    final DeferredComponentsGenSnapshotValidatorTarget validatorTarget = DeferredComponentsGenSnapshotValidatorTarget(
+      dependency: compositeTarget,
+      abis: <String>['arm64-v8a'],
+      title: 'test checks',
+      exitOnFail: false,
+    );
+
+    await validatorTarget.build(environment);
+
+    // We check the inputs to determine if the task was executed.
+    expect(validatorTarget.validator.outputs.length, 1);
+    expect(validatorTarget.validator.outputs[0].path, 'project/deferred_components_loading_units.yaml');
+  });
+}