Decide if unit without directives is a part or a library.

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 'package:analysis_server/edit/fix/fix_core.dart';
 import 'package:analysis_server/src/protocol.dart' hide AnalysisError;
 import 'package:analysis_server/src/services/correction/fix.dart';
 import 'package:analysis_server/src/services/correction/fix_internal.dart';
@@ skipping 258 matching lines @@
 // Comment first.
 // Comment second.
 
 class A {}
 ''';
     addSource('/part.dart', partCode);
     resolveTestUnit('''
 library my.lib;
 part 'part.dart';
 ''');
+    _performAnalysis();
     AnalysisError error = _findErrorToFix();
     fix = _assertHasFix(DartFixKind.ADD_PART_OF, error);
     change = fix.change;
     // apply to "file"
     List<SourceFileEdit> fileEdits = change.edits;
     expect(fileEdits, hasLength(1));
     SourceFileEdit fileEdit = change.edits[0];
     expect(fileEdit.file, '/part.dart');
     expect(SourceEdit.applySequence(partCode, fileEdit.edits), r'''
 // Comment first.
@@ skipping 3619 matching lines @@
   }
 
   List<Position> _findResultPositions(List<String> searchStrings) {
     List<Position> positions = <Position>[];
     for (String search in searchStrings) {
       int offset = resultCode.indexOf(search);
       positions.add(new Position(testFile, offset));
     }
     return positions;
   }
+
+  void _performAnalysis() {
+    while (context.performAnalysisTask().hasMoreWork);
+  }
 }