use 'dart pub' instead of calling the pub executable directly (#97749)

use 'dart pub' instead of calling the pub executable directly

dev/tools/dartdoc.dart

@@ -91,12 +91,12 @@ Future<void> main(List<String> arguments) async {
     pubEnvironment['PUB_CACHE'] = pubCachePath;
   }
 
-  final String pubExecutable = '$flutterRoot/bin/cache/dart-sdk/bin/pub';
+  final String dartExecutable = '$flutterRoot/bin/cache/dart-sdk/bin/dart';
 
   // Run pub.
-  ProcessWrapper process = ProcessWrapper(await Process.start(
-    pubExecutable,
-    <String>['get'],
+  ProcessWrapper process = ProcessWrapper(await runPubProcess(
+    dartBinaryPath: dartExecutable,
+    arguments: <String>['get'],
     workingDirectory: kDocsRoot,
     environment: pubEnvironment,
   ));
@@ -120,8 +120,9 @@ Future<void> main(List<String> arguments) async {
 
   // Verify which version of snippets and dartdoc we're using.
   final ProcessResult snippetsResult = Process.runSync(
-    pubExecutable,
+    dartExecutable,
     <String>[
+      'pub',
       'global',
       'list',
     ],
@@ -216,11 +217,11 @@ Future<void> main(List<String> arguments) async {
   ];
 
   String quote(String arg) => arg.contains(' ') ? "'$arg'" : arg;
-  print('Executing: (cd $kDocsRoot ; $pubExecutable ${dartdocArgs.map<String>(quote).join(' ')})');
+  print('Executing: (cd $kDocsRoot ; $dartExecutable ${dartdocArgs.map<String>(quote).join(' ')})');
 
-  process = ProcessWrapper(await Process.start(
-    pubExecutable,
-    dartdocArgs,
+  process = ProcessWrapper(await runPubProcess(
+    dartBinaryPath: dartExecutable,
+    arguments: dartdocArgs,
     workingDirectory: kDocsRoot,
     environment: pubEnvironment,
   ));
@@ -464,7 +465,6 @@ void putRedirectInOldIndexLocation() {
   File('$kPublishRoot/flutter/index.html').writeAsStringSync(metaTag);
 }
 
-
 void writeSnippetsIndexFile() {
   final Directory snippetsDir = Directory(path.join(kPublishRoot, 'snippets'));
   if (snippetsDir.existsSync()) {
@@ -531,3 +531,18 @@ void printStream(Stream<List<int>> stream, { String prefix = '', List<Pattern> f
         print('$prefix$line'.trim());
     });
 }
+
+Future<Process> runPubProcess({
+  required String dartBinaryPath,
+  required List<String> arguments,
+  String? workingDirectory,
+  Map<String, String>? environment,
+  @visibleForTesting
+  ProcessManager processManager = const LocalProcessManager(),
+}) {
+  return processManager.start(
+    <Object>[dartBinaryPath, 'pub', ...arguments],
+    workingDirectory: workingDirectory,
+    environment: environment,
+  );
+}

dev/tools/test/dartdoc_test.dart

@@ -6,7 +6,7 @@ import 'package:platform/platform.dart';
 import 'package:test/test.dart';
 
 import '../../../packages/flutter_tools/test/src/fake_process_manager.dart';
-import '../dartdoc.dart' show getBranchName;
+import '../dartdoc.dart' show getBranchName, runPubProcess;
 
 void main() {
   const String branchName = 'stable';
@@ -77,4 +77,22 @@ void main() {
     );
     expect(processManager, hasNoRemainingExpectations);
   });
+
+  test("runPubProcess doesn't use the pub binary", () {
+    final ProcessManager processManager = FakeProcessManager.list(
+      <FakeCommand>[
+        const FakeCommand(
+          command: <String>['dart', 'pub', '--one', '--two'],
+        ),
+      ],
+    );
+
+    runPubProcess(
+      dartBinaryPath: 'dart',
+      arguments: <String>['--one', '--two'],
+      processManager: processManager,
+    );
+
+    expect(processManager, hasNoRemainingExpectations);
+  });
 }