[flutter_plugin_tools] Preserve Dart SDK version in all-plugins-app (#5281)

Fixes `all-plugins-app` to preserve the original application's Dart SDK
version to avoid changing language feature opt-ins that the template may
rely on.

Author: stuartmorgan-g

.ci/flutter_master.version

@@ -1 +1 @@
-2b8333240d38cf72b8e13580e24d01f5a188e26c
+329ceaef666ff8cebd4dc36325ab6bfebdc7c8ef

script/tool/CHANGELOG.md

@@ -2,6 +2,9 @@
 
 - Adds a new `readme-check` command.
 - Updates `publish-plugin` command documentation.
+- Fixes `all-plugins-app` to preserve the original application's Dart SDK
+  version to avoid changing language feature opt-ins that the template may
+  rely on.
 
 ## 0.8.2
 

script/tool/lib/src/create_all_plugins_app_command.dart

@@ -147,16 +147,27 @@ class CreateAllPluginsAppCommand extends PluginCommand {
   }
 
   Future<void> _genPubspecWithAllPlugins() async {
+    final RepositoryPackage buildAllApp = RepositoryPackage(appDirectory);
+    // Read the old pubspec file's Dart SDK version, in order to preserve it
+    // in the new file. The template sometimes relies on having opted in to
+    // specific language features via SDK version, so using a different one
+    // can cause compilation failures.
+    final Pubspec originalPubspec = buildAllApp.parsePubspec();
+    const String dartSdkKey = 'sdk';
+    final VersionConstraint dartSdkConstraint =
+        originalPubspec.environment?[dartSdkKey] ??
+            VersionConstraint.compatibleWith(
+              Version.parse('2.12.0'),
+            );
+
     final Map<String, PathDependency> pluginDeps =
         await _getValidPathDependencies();
     final Pubspec pubspec = Pubspec(
       'all_plugins',
       description: 'Flutter app containing all 1st party plugins.',
       version: Version.parse('1.0.0+1'),
       environment: <String, VersionConstraint>{
-        'sdk': VersionConstraint.compatibleWith(
-          Version.parse('2.12.0'),
-        ),
+        dartSdkKey: dartSdkConstraint,
       },
       dependencies: <String, Dependency>{
         'flutter': SdkDependency('flutter'),
@@ -166,8 +177,7 @@ class CreateAllPluginsAppCommand extends PluginCommand {
       },
       dependencyOverrides: pluginDeps,
     );
-    final File pubspecFile = appDirectory.childFile('pubspec.yaml');
-    pubspecFile.writeAsStringSync(_pubspecToString(pubspec));
+    buildAllApp.pubspecFile.writeAsStringSync(_pubspecToString(pubspec));
   }
 
   Future<Map<String, PathDependency>> _getValidPathDependencies() async {
@@ -212,7 +222,12 @@ dev_dependencies:${_pubspecMapString(pubspec.devDependencies)}
     for (final MapEntry<String, dynamic> entry in values.entries) {
       buffer.writeln();
       if (entry.value is VersionConstraint) {
-        buffer.write('  ${entry.key}: ${entry.value}');
+        String value = entry.value.toString();
+        // Range constraints require quoting.
+        if (value.startsWith('>') || value.startsWith('<')) {
+          value = "'$value'";
+        }
+        buffer.write('  ${entry.key}: $value');
       } else if (entry.value is SdkDependency) {
         final SdkDependency dep = entry.value as SdkDependency;
         buffer.write('  ${entry.key}: \n    sdk: ${dep.sdk}');

script/tool/test/create_all_plugins_app_command_test.dart

@@ -2,10 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:io' as io;
+
 import 'package:args/command_runner.dart';
 import 'package:file/file.dart';
 import 'package:file/local.dart';
+import 'package:flutter_plugin_tools/src/common/repository_package.dart';
 import 'package:flutter_plugin_tools/src/create_all_plugins_app_command.dart';
+import 'package:platform/platform.dart';
+import 'package:pubspec_parse/pubspec_parse.dart';
 import 'package:test/test.dart';
 
 import 'util.dart';
@@ -76,14 +81,31 @@ void main() {
           ]));
     });
 
-    test('pubspec is compatible with null-safe app code', () async {
+    test('pubspec preserves existing Dart SDK version', () async {
+      const String baselineProjectName = 'baseline';
+      final Directory baselineProjectDirectory =
+          testRoot.childDirectory(baselineProjectName);
+      io.Process.runSync(
+        getFlutterCommand(const LocalPlatform()),
+        <String>[
+          'create',
+          '--template=app',
+          '--project-name=$baselineProjectName',
+          baselineProjectDirectory.path,
+        ],
+      );
+      final Pubspec baselinePubspec =
+          RepositoryPackage(baselineProjectDirectory).parsePubspec();
+
       createFakePlugin('plugina', packagesDir);
 
       await runCapturingPrint(runner, <String>['all-plugins-app']);
-      final String pubspec =
-          command.appDirectory.childFile('pubspec.yaml').readAsStringSync();
+      final Pubspec generatedPubspec =
+          RepositoryPackage(command.appDirectory).parsePubspec();
 
-      expect(pubspec, contains(RegExp('sdk:\\s*(?:["\']>=|[^])2\\.12\\.')));
+      const String dartSdkKey = 'sdk';
+      expect(generatedPubspec.environment?[dartSdkKey],
+          baselinePubspec.environment?[dartSdkKey]);
     });
 
     test('handles --output-dir', () async {