Locate the template directory using a TemplatePathProvider. (#132156)

So that the paths can be overridden.

packages/flutter_tools/lib/src/ios/application_package.dart

@@ -191,7 +191,7 @@ class BuildableIOSApp extends IOSApp {
 
   // Template asset's images are in flutter_template_images package.
   Future<String> _templateImageAssetDirNameForImages(String asset) async {
-    final Directory imageTemplate = await templateImageDirectory(null, globals.fs, globals.logger);
+    final Directory imageTemplate = await templatePathProvider.imageDirectory(null, globals.fs, globals.logger);
     return globals.fs.path.join(imageTemplate.path, _templateImageAssetDirNameSuffix(asset));
   }
 

packages/flutter_tools/lib/src/template.dart

@@ -7,6 +7,7 @@ import 'package:package_config/package_config.dart';
 import 'package:package_config/package_config_types.dart';
 
 import 'base/common.dart';
+import 'base/context.dart';
 import 'base/file_system.dart';
 import 'base/logger.dart';
 import 'base/template.dart';
@@ -19,6 +20,38 @@ import 'dart/package_map.dart';
 /// https://kotlinlang.org/docs/keyword-reference.html
 const List<String> kReservedKotlinKeywords = <String>['when', 'in', 'is'];
 
+/// Provides the path where templates used by flutter_tools are stored.
+class TemplatePathProvider {
+  const TemplatePathProvider();
+
+  /// Returns the directory containing the 'name' template directory.
+  Directory directoryInPackage(String name, FileSystem fileSystem) {
+    final String templatesDir = fileSystem.path.join(Cache.flutterRoot!,
+        'packages', 'flutter_tools', 'templates');
+    return fileSystem.directory(fileSystem.path.join(templatesDir, name));
+  }
+
+  /// Returns the directory containing the 'name' template directory in
+  /// flutter_template_images, to resolve image placeholder against.
+  /// if 'name' is null, return the parent template directory.
+  Future<Directory> imageDirectory(String? name, FileSystem fileSystem, Logger logger) async {
+    final String toolPackagePath = fileSystem.path.join(
+        Cache.flutterRoot!, 'packages', 'flutter_tools');
+    final String packageFilePath = fileSystem.path.join(toolPackagePath, '.dart_tool', 'package_config.json');
+    final PackageConfig packageConfig = await loadPackageConfigWithLogging(
+      fileSystem.file(packageFilePath),
+      logger: logger,
+    );
+    final Uri? imagePackageLibDir = packageConfig['flutter_template_images']?.packageUriRoot;
+    final Directory templateDirectory = fileSystem.directory(imagePackageLibDir)
+        .parent
+        .childDirectory('templates');
+    return name == null ? templateDirectory : templateDirectory.childDirectory(name);
+  }
+}
+
+TemplatePathProvider get templatePathProvider => context.get<TemplatePathProvider>() ?? const TemplatePathProvider();
+
 /// Expands templates in a directory to a destination. All files that must
 /// undergo template expansion should end with the '.tmpl' extension. All files
 /// that should be replaced with the corresponding image from
@@ -100,8 +133,8 @@ class Template {
     required TemplateRenderer templateRenderer,
   }) async {
     // All named templates are placed in the 'templates' directory
-    final Directory templateDir = _templateDirectoryInPackage(name, fileSystem);
-    final Directory imageDir = await templateImageDirectory(name, fileSystem, logger);
+    final Directory templateDir = templatePathProvider.directoryInPackage(name, fileSystem);
+    final Directory imageDir = await templatePathProvider.imageDirectory(name, fileSystem, logger);
     return Template._(
       <Directory>[templateDir],
       <Directory>[imageDir],
@@ -122,12 +155,12 @@ class Template {
     return Template._(
       <Directory>[
         for (final String name in names)
-          _templateDirectoryInPackage(name, fileSystem),
+          templatePathProvider.directoryInPackage(name, fileSystem),
       ],
       <Directory>[
         for (final String name in names)
-          if ((await templateImageDirectory(name, fileSystem, logger)).existsSync())
-            await templateImageDirectory(name, fileSystem, logger),
+          if ((await templatePathProvider.imageDirectory(name, fileSystem, logger)).existsSync())
+            await templatePathProvider.imageDirectory(name, fileSystem, logger),
       ],
       fileSystem: fileSystem,
       logger: logger,
@@ -344,30 +377,6 @@ class Template {
   }
 }
 
-Directory _templateDirectoryInPackage(String name, FileSystem fileSystem) {
-  final String templatesDir = fileSystem.path.join(Cache.flutterRoot!,
-      'packages', 'flutter_tools', 'templates');
-  return fileSystem.directory(fileSystem.path.join(templatesDir, name));
-}
-
-/// Returns the directory containing the 'name' template directory in
-/// flutter_template_images, to resolve image placeholder against.
-/// if 'name' is null, return the parent template directory.
-Future<Directory> templateImageDirectory(String? name, FileSystem fileSystem, Logger logger) async {
-  final String toolPackagePath = fileSystem.path.join(
-      Cache.flutterRoot!, 'packages', 'flutter_tools');
-  final String packageFilePath = fileSystem.path.join(toolPackagePath, '.dart_tool', 'package_config.json');
-  final PackageConfig packageConfig = await loadPackageConfigWithLogging(
-    fileSystem.file(packageFilePath),
-    logger: logger,
-  );
-  final Uri? imagePackageLibDir = packageConfig['flutter_template_images']?.packageUriRoot;
-  final Directory templateDirectory = fileSystem.directory(imagePackageLibDir)
-      .parent
-      .childDirectory('templates');
-  return name == null ? templateDirectory : templateDirectory.childDirectory(name);
-}
-
 String _escapeKotlinKeywords(String androidIdentifier) {
   final List<String> segments = androidIdentifier.split('.');
   final List<String> correctedSegments = segments.map(

packages/flutter_tools/test/general.shard/template_test.dart

@@ -51,8 +51,9 @@ void main() {
       FileSystem: () => MemoryFileSystem.test(),
       ProcessManager: () => FakeProcessManager.any(),
     };
+    const TemplatePathProvider templatePathProvider = TemplatePathProvider();
 
-    testUsingContext('templateImageDirectory returns parent template directory if passed null name', () async {
+    testUsingContext('templatePathProvider.imageDirectory returns parent template directory if passed null name', () async {
       final String packageConfigPath = globals.fs.path.join(
         Cache.flutterRoot!,
         'packages',
@@ -77,7 +78,7 @@ void main() {
 }
 ''');
       expect(
-          (await templateImageDirectory(null, globals.fs, globals.logger)).path,
+          (await templatePathProvider.imageDirectory(null, globals.fs, globals.logger)).path,
           globals.fs.path.absolute(
             'flutter_template_images',
             'templates',
@@ -85,7 +86,7 @@ void main() {
       );
     }, overrides: overrides);
 
-    testUsingContext('templateImageDirectory returns the directory containing the `name` template directory', () async {
+    testUsingContext('templatePathProvider.imageDirectory returns the directory containing the `name` template directory', () async {
       final String packageConfigPath = globals.fs.path.join(
         Cache.flutterRoot!,
         'packages',
@@ -109,7 +110,7 @@ void main() {
 }
 ''');
       expect(
-        (await templateImageDirectory('app_shared', globals.fs, globals.logger)).path,
+        (await templatePathProvider.imageDirectory('app_shared', globals.fs, globals.logger)).path,
         globals.fs.path.absolute(
           'flutter_template_images',
           'templates',