Add fix for missing @required params.

pkg/analysis_server/test/services/correction/fix_test.dart

 // Copyright (c) 2014, 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.
 
 library test.services.correction.fix;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/edit/fix/fix_core.dart';
 import 'package:analysis_server/plugin/edit/fix/fix_dart.dart';
@@ skipping 409 matching lines @@
         '''
 class A {
   test(int i) {}
   main() {
     test(1);
   }
 }
 ''');
   }
 
+  test_addMissingRequiredArg_cons_single() async {
+    _addMetaPackageSource();
+
+    await resolveTestUnit('''
+import 'package:meta/meta.dart';
+
+class A {
+  A({@required int a}) {}
+}
+main() {
+  A a = new A();
+}
+''');
+    await assertHasFix(
+        DartFixKind.ADD_MISSING_REQUIRED_ARGUMENT,
+        '''
+import 'package:meta/meta.dart';
+
+class A {
+  A({@required int a}) {}
+}
+main() {
+  A a = new A(a: null);
+}
+''');
+  }
+
+  test_addMissingRequiredArg_multiple() async {
+    _addMetaPackageSource();
+
+    await resolveTestUnit('''
+import 'package:meta/meta.dart';
+
+test({@required int a, @required int bcd}) {}
+main() {
+  test(a: 3);
+}
+''');
+    await assertHasFix(
+        DartFixKind.ADD_MISSING_REQUIRED_ARGUMENT,
+        '''
+import 'package:meta/meta.dart';
+
+test({@required int a, @required int bcd}) {}
+main() {
+  test(a: 3, bcd: null);
+}
+''');
+  }
+
+  test_addMissingRequiredArg_single() async {
+    _addMetaPackageSource();
+
+    await resolveTestUnit('''
+import 'package:meta/meta.dart';
+
+test({@required int abc}) {}
+main() {
+  test();
+}
+''');
+    await assertHasFix(
+        DartFixKind.ADD_MISSING_REQUIRED_ARGUMENT,
+        '''
+import 'package:meta/meta.dart';
+
+test({@required int abc}) {}
+main() {
+  test(abc: null);
+}
+''');
+  }
+
+  test_addMissingRequiredArg_single_normal() async {
+    _addMetaPackageSource();
+
+    await resolveTestUnit('''
+import 'package:meta/meta.dart';
+
+test(String x, {@required int abc}) {}
+main() {
+  test("foo");
+}
+''');
+    await assertHasFix(
+        DartFixKind.ADD_MISSING_REQUIRED_ARGUMENT,
+        '''
+import 'package:meta/meta.dart';
+
+test(String x, {@required int abc}) {}
+main() {
+  test("foo", abc: null);
+}
+''');
+  }
+
   test_addSync_asyncFor() async {
     await resolveTestUnit('''
 import 'dart:async';
 void main(Stream<String> names) {
   await for (String name in names) {
     print(name);
   }
 }
 ''');
     await assertHasFix(
@@ skipping 4889 matching lines @@
     await assertHasFix(
         DartFixKind.IMPORT_LIBRARY_PREFIX,
         '''
 import 'dart:math' as pref;
 main() {
   print(pref.E);
   print(pref.PI);
 }
 ''');
   }
+
+  void _addMetaPackageSource() {
+    addPackageSource('meta', 'meta.dart', r'''
+library meta;
+
+const Required required = const Required();
+
+class Required {
+  final String reason;
+  const Required([this.reason]);
+}
+''');
+  }
 }
 
 @reflectiveTest
 class FixProcessorTest_Driver extends FixProcessorTest {
   @override
   bool get enableNewAnalysisDriver => true;
 
   @failingTest
   @override
   test_importLibrarySdk_withClass_AsExpression() {
@@ skipping 305 matching lines @@
 
   @override
   final CompilationUnit unit;
 
   @override
   final AnalysisError error;
 
   _DartFixContextImpl(this.resourceProvider, this.getTopLevelDeclarations,
       this.analysisContext, this.astProvider, this.unit, this.error);
 }