Add a fix to insert the keyword late

Change-Id: I40612fd2710a1189137d8ba676c1b66b4943d677
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/151037
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

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

@@ -0,0 +1,55 @@
+// 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/dart/ast/token.dart';
+import 'package:analyzer_plugin/utilities/change_builder/change_builder_dart.dart';
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
+
+class AddLate extends CorrectionProducer {
+  @override
+  FixKind get fixKind => DartFixKind.ADD_LATE;
+
+  @override
+  Future<void> compute(DartChangeBuilder builder) async {
+    if (!libraryElement.isNonNullableByDefault) {
+      return;
+    }
+    if (node is SimpleIdentifier &&
+        node.parent is VariableDeclaration &&
+        node.parent.parent is VariableDeclarationList) {
+      var list = node.parent.parent as VariableDeclarationList;
+      if (!list.isLate) {
+        if (list.type == null) {
+          var keyword = list.keyword;
+          if (keyword == null) {
+            await _insertAt(builder, list.variables[0].offset);
+            // TODO(brianwilkerson) Consider converting this into an assist and
+            //  expand it to support converting `var` to `late` as well as
+            //  working anywhere a non-late local variable or field is selected.
+//          } else if (keyword.type == Keyword.VAR) {
+//            builder.addFileEdit(file, (builder) {
+//              builder.addSimpleReplacement(range.token(keyword), 'late');
+//            });
+          } else if (keyword.type != Keyword.CONST) {
+            await _insertAt(builder, list.variables[0].offset);
+          }
+        } else {
+          await _insertAt(builder, list.type.offset);
+        }
+      }
+    }
+  }
+
+  void _insertAt(DartChangeBuilder builder, int offset) async {
+    await builder.addFileEdit(file, (builder) {
+      builder.addSimpleInsertion(offset, 'late ');
+    });
+  }
+
+  /// Return an instance of this class. Used as a tear-off in `FixProcessor`.
+  static AddLate newInstance() => AddLate();
+}

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

@@ -154,6 +154,8 @@ class DartFixKind {
       'dart.fix.add.fieldFormalParameters',
       70,
       'Add final field formal parameters');
+  static const ADD_LATE =
+      FixKind('dart.fix.add.late', 50, "Add 'late' modifier");
   static const ADD_MISSING_ENUM_CASE_CLAUSES = FixKind(
       'dart.fix.add.missingEnumCaseClauses', 50, 'Add missing case clauses');
   static const ADD_MISSING_PARAMETER_NAMED = FixKind(

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

@@ -15,6 +15,7 @@ import 'package:analysis_server/src/services/correction/dart/add_const.dart';
 import 'package:analysis_server/src/services/correction/dart/add_diagnostic_property_reference.dart';
 import 'package:analysis_server/src/services/correction/dart/add_explicit_cast.dart';
 import 'package:analysis_server/src/services/correction/dart/add_field_formal_parameters.dart';
+import 'package:analysis_server/src/services/correction/dart/add_late.dart';
 import 'package:analysis_server/src/services/correction/dart/add_missing_enum_case_clauses.dart';
 import 'package:analysis_server/src/services/correction/dart/add_missing_parameter.dart';
 import 'package:analysis_server/src/services/correction/dart/add_missing_parameter_named.dart';
@@ -627,6 +628,9 @@ class FixProcessor extends BaseProcessor {
       ChangeTo.classOrMixin,
       CreateClass.newInstance,
     ],
+    CompileTimeErrorCode.NOT_INITIALIZED_NON_NULLABLE_INSTANCE_FIELD: [
+      AddLate.newInstance,
+    ],
     CompileTimeErrorCode.NULLABLE_TYPE_IN_EXTENDS_CLAUSE: [
       RemoveQuestionMark.newInstance,
     ],
@@ -912,6 +916,7 @@ class FixProcessor extends BaseProcessor {
       RemoveDeadIfNull.newInstance,
     ],
     StaticWarningCode.FINAL_NOT_INITIALIZED: [
+      AddLate.newInstance,
       CreateConstructorForFinalFields.newInstance,
     ],
     StaticWarningCode.FINAL_NOT_INITIALIZED_CONSTRUCTOR_1: [

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

@@ -0,0 +1,76 @@
+// 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/fix.dart';
+import 'package:analyzer/src/dart/analysis/experiments.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(AddLatePreNnbdTest);
+    defineReflectiveTests(AddLateTest);
+  });
+}
+
+@reflectiveTest
+class AddLatePreNnbdTest extends FixProcessorTest {
+  @override
+  FixKind get kind => DartFixKind.ADD_LATE;
+
+  Future<void> test_withFinal() async {
+    await resolveTestUnit('''
+class C {
+  final String s;
+}
+''');
+    await assertNoFix();
+  }
+}
+
+@reflectiveTest
+class AddLateTest extends FixProcessorTest {
+  @override
+  List<String> get experiments => [EnableString.non_nullable];
+
+  @override
+  FixKind get kind => DartFixKind.ADD_LATE;
+
+  Future<void> test_withFinal() async {
+    await resolveTestUnit('''
+class C {
+  final String s;
+}
+''');
+    await assertHasFix('''
+class C {
+  final late String s;
+}
+''');
+  }
+
+  Future<void> test_withLate() async {
+    await resolveTestUnit('''
+class C {
+  late s;
+}
+''');
+    await assertNoFix();
+  }
+
+  Future<void> test_withType() async {
+    await resolveTestUnit('''
+class C {
+  String s;
+}
+''');
+    await assertHasFix('''
+class C {
+  late String s;
+}
+''');
+  }
+}

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

@@ -12,6 +12,7 @@ import 'add_diagnostic_property_reference_test.dart'
     as add_diagnostic_property_reference;
 import 'add_explicit_cast_test.dart' as add_explicit_cast;
 import 'add_field_formal_parameters_test.dart' as add_field_formal_parameters;
+import 'add_late_test.dart' as add_late;
 import 'add_missing_enum_case_clauses_test.dart'
     as add_missing_enum_case_clauses;
 import 'add_missing_parameter_named_test.dart' as add_missing_parameter_named;
@@ -170,6 +171,7 @@ void main() {
     add_diagnostic_property_reference.main();
     add_explicit_cast.main();
     add_field_formal_parameters.main();
+    add_late.main();
     add_missing_enum_case_clauses.main();
     add_missing_parameter_named.main();
     add_missing_parameter_positional.main();