Add support to dartfix to fix unnecessary new and const lints

Change-Id: I8345ea6afd5aa43bda4855b24d101c04b177ae80
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/128522
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

pkg/analysis_server/lib/src/edit/fix/basic_fix_lint_error_task.dart

@@ -50,4 +50,20 @@ class BasicFixLintErrorTask extends FixLintTask {
           DartFixKind.REPLACE_WITH_IS_NOT_EMPTY, listener),
     );
   }
+
+  static void unnecessaryConst(DartFixRegistrar registrar,
+      DartFixListener listener, EditDartfixParams params) {
+    registrar.registerLintTask(
+      Registry.ruleRegistry['unnecessary_const'],
+      new BasicFixLintErrorTask(DartFixKind.REMOVE_UNNECESSARY_CONST, listener),
+    );
+  }
+
+  static void unnecessaryNew(DartFixRegistrar registrar,
+      DartFixListener listener, EditDartfixParams params) {
+    registrar.registerLintTask(
+      Registry.ruleRegistry['unnecessary_new'],
+      new BasicFixLintErrorTask(DartFixKind.REMOVE_UNNECESSARY_NEW, listener),
+    );
+  }
 }

pkg/analysis_server/lib/src/edit/fix/dartfix_info.dart

@@ -106,6 +106,32 @@ will be converted to
     isDefault: false,
     isPedantic: true,
   ),
+  const DartFixInfo(
+    'unnecessary-const',
+    '''
+Remove unnecessary `const` keywords.
+
+For example, this
+  static const digits = const ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'];
+
+will be converted to
+  static const digits = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'];''',
+    BasicFixLintErrorTask.unnecessaryConst,
+    isPedantic: true,
+  ),
+  const DartFixInfo(
+    'unnecessary-new',
+    '''
+Remove unnecessary `new` keywords.
+
+For example, this
+  var marker = new Object();
+
+will be converted to
+  var marker = Object();''',
+    BasicFixLintErrorTask.unnecessaryNew,
+    isPedantic: true,
+  ),
   //
   // Other fixes
   //

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

@@ -3197,9 +3197,16 @@ class FixProcessor extends BaseProcessor {
   }
 
   Future<void> _addFix_removeConstKeyword() async {
-    final instanceCreationExpression = node;
-    if (instanceCreationExpression is InstanceCreationExpression) {
-      final constToken = instanceCreationExpression.keyword;
+    final expression = node;
+    if (expression is InstanceCreationExpression) {
+      final constToken = expression.keyword;
+      var changeBuilder = _newDartChangeBuilder();
+      await changeBuilder.addFileEdit(file, (DartFileEditBuilder builder) {
+        builder.addDeletion(range.startStart(constToken, constToken.next));
+      });
+      _addFixFromBuilder(changeBuilder, DartFixKind.REMOVE_UNNECESSARY_CONST);
+    } else if (expression is TypedLiteralImpl) {
+      final constToken = expression.constKeyword;
       var changeBuilder = _newDartChangeBuilder();
       await changeBuilder.addFileEdit(file, (DartFileEditBuilder builder) {
         builder.addDeletion(range.startStart(constToken, constToken.next));

pkg/analysis_server/test/domain_edit_dartfix_test.dart

@@ -136,17 +136,17 @@ const double myDouble = 42.0;
     addTestFile('''
 class A<T> { A.from(Object obj) { } }
 main() {
-  print(new A.from<String>([]));
+  print(A.from<String>([]));
 }
     ''');
     createProject();
     EditDartfixResult result = await performFix();
     expect(result.suggestions, hasLength(1));
-    expectSuggestion(result.suggestions[0], 'type arguments', 65, 8);
+    expectSuggestion(result.suggestions[0], 'type arguments', 61, 8);
     expectEdits(result.edits, '''
 class A<T> { A.from(Object obj) { } }
 main() {
-  print(new A<String>.from([]));
+  print(A<String>.from([]));
 }
     ''');
   }

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

@@ -128,6 +128,7 @@ import 'replace_with_is_not_empty_test.dart' as replace_with_is_not_empty;
 import 'replace_with_null_aware_test.dart' as replace_with_null_aware;
 import 'replace_with_tear_off_test.dart' as replace_with_tear_off;
 import 'sort_child_property_last_test.dart' as sort_properties_last;
+import 'unnecessary_const_test.dart' as unnecessary_const;
 import 'update_sdk_constraints_test.dart' as update_sdk_constraints;
 import 'use_const_test.dart' as use_const;
 import 'use_effective_integer_division_test.dart'
@@ -249,6 +250,7 @@ main() {
     replace_with_null_aware.main();
     replace_with_tear_off.main();
     sort_properties_last.main();
+    unnecessary_const.main();
     update_sdk_constraints.main();
     use_const.main();
     use_effective_integer_division.main();

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

@@ -0,0 +1,43 @@
+// Copyright (c) 2019, 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';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(UnnecessaryConstTest);
+  });
+}
+
+@reflectiveTest
+class UnnecessaryConstTest extends FixProcessorLintTest {
+  @override
+  FixKind get kind => DartFixKind.REMOVE_UNNECESSARY_CONST;
+
+  @override
+  String get lintCode => LintNames.unnecessary_const;
+
+  test_instanceCreation() async {
+    await resolveTestUnit('''
+const list = /*LINT*/const List();
+''');
+    await assertHasFix('''
+const list = /*LINT*/List();
+''', length: 5);
+  }
+
+  test_typedLiteral() async {
+    await resolveTestUnit('''
+const list = /*LINT*/const [];
+''');
+    await assertHasFix('''
+const list = /*LINT*/[];
+''', length: 5);
+  }
+}