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 278 matching lines @@
   test_addMissingParameter_function_positional_hasNamed() async {
     await resolveTestUnit('''
 test({int a}) {}
 main() {
   test(1);
 }
 ''');
     await assertNoFix(DartFixKind.ADD_MISSING_PARAMETER_POSITIONAL);
   }
 
+  void _addMetaPackageSource() {

[scheglov, 2017/02/14 22:06:07]

Please format and sort and files that you change in analyzer and analysis
server.

[pquitslund, 2017/02/14 23:41:38]

Whoops!  I got confused by the "Rearrange Code" action which I *thought* was
doing the right thing.  (PS: it's annoying that it doesn't!)

+    addPackageSource('meta', 'meta.dart', r'''
+library meta;
+
+const Required required = const Required();
+
+class Required {
+  final String reason;
+  const Required([this.reason]);
+}
+''');
+  }
+
+  test_addMissingRequiredParam_single() async {
+    _addMetaPackageSource();
+
+    await resolveTestUnit('''
+import 'package:meta/meta.dart';
+
+test({@required int a}) {}
+main() {
+  test();
+}
+''');
+    await assertHasFix(
+        DartFixKind.ADD_MISSING_REQUIRED_PARAMETER,
+        '''
+import 'package:meta/meta.dart';
+
+test({@required int a}) {}
+main() {
+  test(a: null);
+}
+''');
+  }
+
+  test_addMissingRequiredParam_multiple() async {

[scheglov, 2017/02/14 22:06:07]

This looks like "_hasOtherArgument" test.
But yes, adding multiple required arguments should be nice.

[pquitslund, 2017/02/14 23:41:38]

Acknowledged.

+    _addMetaPackageSource();
+
+    await resolveTestUnit('''
+import 'package:meta/meta.dart';
+
+test({@required int a, @required int b}) {}
+main() {
+  test(a: 3);
+}
+''');
+    await assertHasFix(
+        DartFixKind.ADD_MISSING_REQUIRED_PARAMETER,
+        '''
+import 'package:meta/meta.dart';
+
+test({@required int a, @required int b}) {}
+main() {
+  test(a: 3, b: null);
+}
+''');
+  }
+
   test_addMissingParameter_function_positional_hasZero() async {
     await resolveTestUnit('''
 test() {}
 main() {
   test(1);
 }
 ''');
     await assertHasFix(
         DartFixKind.ADD_MISSING_PARAMETER_POSITIONAL,
         '''
@@ skipping 5345 matching lines @@
 
   @override
   final CompilationUnit unit;
 
   @override
   final AnalysisError error;
 
   _DartFixContextImpl(this.resourceProvider, this.getTopLevelDeclarations,
       this.analysisContext, this.astProvider, this.unit, this.error);
 }