[flutter_tools] add package_config.json to analyze_once_test.dart (#69059)

* [flutter_tools] add package_config.json to analyze_once_test.dart

packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart

@@ -65,7 +65,7 @@ void main() {
     logger.clear();
   }
 
-  void _createDotPackages(String projectPath) {
+  void _createDotPackages(String projectPath, [bool nullSafe = false]) {
     final StringBuffer flutterRootUri = StringBuffer('file://');
     final String canonicalizedFlutterRootPath = fileSystem.path.canonicalize(Cache.flutterRoot);
     if (platform.isWindows) {
@@ -76,12 +76,32 @@ void main() {
       flutterRootUri.write(canonicalizedFlutterRootPath);
     }
     final String dotPackagesSrc = '''
-# Generated
-flutter:$flutterRootUri/packages/flutter/lib/
-sky_engine:$flutterRootUri/bin/cache/pkg/sky_engine/lib/
-flutter_project:lib/
+{
+  "configVersion": 2,
+  "packages": [
+    {
+      "name": "flutter",
+      "rootUri": "$flutterRootUri/packages/flutter",
+      "packageUri": "lib/",
+      "languageVersion": "2.10"
+    },
+    {
+      "name": "sky_engine",
+      "rootUri": "$flutterRootUri/bin/cache/pkg/sky_engine",
+      "packageUri": "lib/",
+      "languageVersion": "2.10"
+    },
+    {
+      "name": "flutter_project",
+      "rootUri": "../",
+      "packageUri": "lib/",
+      "languageVersion": "${nullSafe ? "2.10" : "2.7"}"
+    }
+  ]
+}
 ''';
-    fileSystem.file(fileSystem.path.join(projectPath, '.packages'))
+
+    fileSystem.file(fileSystem.path.join(projectPath, '.dart_tool', 'package_config.json'))
       ..createSync(recursive: true)
       ..writeAsStringSync(dotPackagesSrc);
   }
@@ -330,7 +350,7 @@ StringBuffer bar = StringBuffer('baz');
 int? bar;
 ''';
     final Directory tempDir = fileSystem.systemTempDirectory.createTempSync('flutter_analyze_once_test_null_safety.');
-    _createDotPackages(tempDir.path);
+    _createDotPackages(tempDir.path, true);
 
     tempDir.childFile('main.dart').writeAsStringSync(contents);
     try {