Add two fixes for avoid_returning_null_for_future

Change-Id: I6ece892025233fe3dd51ececb7b92368be9669ae
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/138321
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: bwilkerson

pkg/analysis_server/lib/src/services/correction/dart/wrap_in_future.dart

@@ -0,0 +1,38 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analysis_server/src/services/correction/dart/abstract_producer.dart';
+import 'package:analysis_server/src/services/correction/fix.dart';
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer_plugin/utilities/change_builder/change_builder_dart.dart';
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
+import 'package:analyzer_plugin/utilities/range_factory.dart';
+
+class WrapInFuture extends CorrectionProducer {
+  @override
+  FixKind get fixKind => DartFixKind.WRAP_IN_FUTURE;
+
+  @override
+  Future<void> compute(DartChangeBuilder builder) async {
+    //
+    // Extract the information needed to build the edit.
+    //
+    Expression expression;
+    if (node is ReturnStatement) {
+      expression = (node as ReturnStatement).expression;
+    } else if (node is Expression) {
+      expression = node;
+    } else {
+      return;
+    }
+    var value = utils.getNodeText(expression);
+    //
+    // Build the edit.
+    //
+    await builder.addFileEdit(file, (DartFileEditBuilder builder) {
+      builder.addSimpleReplacement(
+          range.node(expression), 'Future.value($value)');
+    });
+  }
+}

pkg/analysis_server/lib/src/services/correction/fix.dart

@@ -409,6 +409,8 @@ class DartFixKind {
           "Use != null instead of 'is! Null' everywhere in file");
   static const USE_RETHROW =
       FixKind('USE_RETHROW', 50, 'Replace throw with rethrow');
+  static const WRAP_IN_FUTURE =
+      FixKind('WRAP_IN_FUTURE', 50, "Wrap in 'Future.value'");
 }
 
 /// An enumeration of quick fix kinds for the errors found in an Android

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

@@ -21,6 +21,7 @@ import 'package:analysis_server/src/services/correction/dart/convert_to_where_ty
 import 'package:analysis_server/src/services/correction/dart/remove_dead_if_null.dart';
 import 'package:analysis_server/src/services/correction/dart/remove_if_null_operator.dart';
 import 'package:analysis_server/src/services/correction/dart/replace_with_eight_digit_hex.dart';
+import 'package:analysis_server/src/services/correction/dart/wrap_in_future.dart';
 import 'package:analysis_server/src/services/correction/fix.dart';
 import 'package:analysis_server/src/services/correction/fix/dart/top_level_declarations.dart';
 import 'package:analysis_server/src/services/correction/levenshtein.dart';
@@ -629,6 +630,9 @@ class FixProcessor extends BaseProcessor {
       if (name == LintNames.avoid_return_types_on_setters) {
         await _addFix_removeTypeAnnotation();
       }
+      if (name == LintNames.avoid_returning_null_for_future) {
+        await _addFix_addAsync();
+      }
       if (name == LintNames.avoid_types_on_closure_parameters) {
         await _addFix_replaceWithIdentifier();
       }
@@ -4713,7 +4717,9 @@ class FixProcessor extends BaseProcessor {
       await compute(RemoveDeadIfNull());
     } else if (errorCode is LintCode) {
       String name = errorCode.name;
-      if (name == LintNames.prefer_collection_literals) {
+      if (name == LintNames.avoid_returning_null_for_future) {
+        await compute(WrapInFuture());
+      } else if (name == LintNames.prefer_collection_literals) {
         await compute(ConvertToListLiteral());
         await compute(ConvertToMapLiteral());
         await compute(ConvertToSetLiteral());

pkg/analysis_server/lib/src/services/linter/lint_names.dart

@@ -19,6 +19,8 @@ class LintNames {
   static const String avoid_relative_lib_imports = 'avoid_relative_lib_imports';
   static const String avoid_return_types_on_setters =
       'avoid_return_types_on_setters';
+  static const String avoid_returning_null_for_future =
+      'avoid_returning_null_for_future';
   static const String avoid_types_on_closure_parameters =
       'avoid_types_on_closure_parameters';
   static const String await_only_futures = 'await_only_futures';

pkg/analysis_server/test/src/services/correction/fix/add_async_test.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analysis_server/src/services/correction/fix.dart';
+import 'package:analysis_server/src/services/linter/lint_names.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
@@ -13,6 +14,7 @@ import 'fix_processor.dart';
 void main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(AddAsyncTest);
+    defineReflectiveTests(AvoidReturningNullForFutureTest);
   });
 }
 
@@ -183,3 +185,25 @@ main() async {
 ''');
   }
 }
+
+@reflectiveTest
+class AvoidReturningNullForFutureTest extends FixProcessorLintTest {
+  @override
+  FixKind get kind => DartFixKind.ADD_ASYNC;
+
+  @override
+  String get lintCode => LintNames.avoid_returning_null_for_future;
+
+  Future<void> test_asyncFor() async {
+    await resolveTestUnit('''
+Future<String> f() {
+  return null;
+}
+''');
+    await assertHasFix('''
+Future<String> f() async {
+  return null;
+}
+''');
+  }
+}

pkg/analysis_server/test/src/services/correction/fix/test_all.dart

@@ -150,6 +150,7 @@ import 'use_eq_eq_null_test.dart' as use_eq_eq_null;
 import 'use_is_not_empty_test.dart' as use_is_not_empty;
 import 'use_not_eq_null_test.dart' as use_not_eq_null;
 import 'use_rethrow_test.dart' as use_rethrow;
+import 'wrap_in_future_test.dart' as wrap_in_future;
 
 void main() {
   defineReflectiveSuite(() {
@@ -283,5 +284,6 @@ void main() {
     use_is_not_empty.main();
     use_not_eq_null.main();
     use_rethrow.main();
+    wrap_in_future.main();
   }, name: 'fix');
 }

pkg/analysis_server/test/src/services/correction/fix/wrap_in_future_test.dart

@@ -0,0 +1,38 @@
+// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analysis_server/src/services/correction/fix.dart';
+import 'package:analysis_server/src/services/linter/lint_names.dart';
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import 'fix_processor.dart';
+
+void main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(WrapInFutureTest);
+  });
+}
+
+@reflectiveTest
+class WrapInFutureTest extends FixProcessorLintTest {
+  @override
+  FixKind get kind => DartFixKind.WRAP_IN_FUTURE;
+
+  @override
+  String get lintCode => LintNames.avoid_returning_null_for_future;
+
+  Future<void> test_asyncFor() async {
+    await resolveTestUnit('''
+Future<String> f() {
+  return null;
+}
+''');
+    await assertHasFix('''
+Future<String> f() {
+  return Future.value(null);
+}
+''');
+  }
+}