Fix for 'returnType' when extract a method with a single expression.

pkg/analysis_server/test/services/refactoring/extract_method_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.refactoring.extract_method;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/refactoring/extract_method.dart';
@@ skipping 1014 matching lines @@
     return refactoring.checkInitialConditions().then((_) {
       expect(
           refactoring.names,
           unorderedEquals(['selectedItem', 'item', 'my', 'treeItem2']));
     });
   }
 
   test_offsets_lengths() {
     indexTestUnit('''
 main() {
-main() {
   int a = 1 + 2;
   int b = 1 +  2;
 }
-}
 ''');
     _createRefactoringForString('1 +  2');
     // apply refactoring
     return refactoring.checkInitialConditions().then((_) {
       expect(
           refactoring.offsets,
           unorderedEquals([findOffset('1 + 2'), findOffset('1 +  2')]));
       expect(refactoring.lengths, unorderedEquals([5, 6]));
     });
   }
 
+  test_returnType_expression() {
+    indexTestUnit('''
+main() {
+  int a = 1 + 2;
+}
+''');
+    _createRefactoringForString('1 + 2');
+    // do check
+    return refactoring.checkInitialConditions().then((_) {
+      expect(refactoring.returnType, 'int');
+    });
+  }
+
+  test_returnType_statements() {
+    indexTestUnit('''
+main() {
+// start
+  double v = 5.0;
+// end
+  print(v);
+}
+''');
+    _createRefactoringForStartEndComments();
+    // do check
+    return refactoring.checkInitialConditions().then((_) {
+      expect(refactoring.returnType, 'double');
+    });
+  }
+
+  test_returnType_statements_void() {
+    indexTestUnit('''
+main() {
+// start
+  print(42);
+// end
+}
+''');
+    _createRefactoringForStartEndComments();
+    // do check
+    return refactoring.checkInitialConditions().then((_) {
+      expect(refactoring.returnType, 'void');
+    });
+  }
+
   test_setExtractGetter() {
     indexTestUnit('''
 main() {
   int a = 1 + 2;
 }
 ''');
     _createRefactoringForString('1 + 2');
     // apply refactoring
     return assertRefactoringConditionsOK().then((_) {
       expect(refactoring.canCreateGetter, true);
@@ skipping 1194 matching lines @@
     int length = search.length;
     _createRefactoring(offset, length);
   }
 
   void _createRefactoringWithSuffix(String selectionSearch, String suffix) {
     int offset = findOffset(selectionSearch + suffix);
     int length = selectionSearch.length;
     _createRefactoring(offset, length);
   }
 }