Issue 24298. Fix for 'async' function body conversion.

pkg/analysis_server/test/services/correction/assist_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.assist;
 
 import 'package:analysis_server/edit/assist/assist_core.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/correction/assist.dart';
@@ skipping 805 matching lines @@
   void test_assignToLocalVariable_void() {
     resolveTestUnit('''
 main() {
   f();
 }
 void f() {}
 ''');
     assertNoAssistAt('f();', DartAssistKind.ASSIGN_TO_LOCAL_VARIABLE);
   }
 
+  void test_convertToBlockBody_OK_async() {
+    resolveTestUnit('''
+class A {
+  mmm() async => 123;
+}
+''');
+    assertHasAssistAt(
+        'mmm()',
+        DartAssistKind.CONVERT_INTO_BLOCK_BODY,
+        '''
+class A {
+  mmm() async {
+    return 123;
+  }
+}
+''');
+  }
+
   void test_convertToBlockBody_OK_closure() {
     resolveTestUnit('''
 setup(x) {}
 main() {
   setup(() => 42);
 }
 ''');
     assertHasAssistAt(
         '() => 42',
         DartAssistKind.CONVERT_INTO_BLOCK_BODY,
@@ skipping 112 matching lines @@
 
   void test_convertToBlockBody_wrong_notExpressionBlock() {
     resolveTestUnit('''
 fff() {
   return 123;
 }
 ''');
     assertNoAssistAt('fff() {', DartAssistKind.CONVERT_INTO_BLOCK_BODY);
   }
 
+  void test_convertToExpressionBody_OK_async() {
+    resolveTestUnit('''
+class A {
+  mmm() async {
+    return 42;
+  }
+}
+''');
+    assertHasAssistAt(
+        'mmm',
+        DartAssistKind.CONVERT_INTO_EXPRESSION_BODY,
+        '''
+class A {
+  mmm() async => 42;
+}
+''');
+  }
+
   void test_convertToExpressionBody_OK_closure() {
     resolveTestUnit('''
 setup(x) {}
 main() {
   setup(() {
     return 42;
   });
 }
 ''');
     assertHasAssistAt(
@@ skipping 2673 matching lines @@
       positions.add(new Position(testFile, offset));
     }
     return positions;
   }
 
   void _setStartEndSelection() {
     offset = findOffset('// start\n') + '// start\n'.length;
     length = findOffset('// end') - offset;
   }
 }