Quick Fix for missing 'part of' directive.

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 144 matching lines @@
     assertHasFix(DartFixKind.ADD_FIELD_FORMAL_PARAMETERS, '''
 class Test {
   final int a;
   final int b;
   final int c;
   Test(this.a, this.b, [this.c]);
 }
 ''');
   }
 
+  void test_addPartOfDirective() {
+    String partCode = r'''
+// Comment first.
+// Comment second.
+
+class A {}
+''';
+    addSource('/part.dart', partCode);
+    resolveTestUnit('''
+library my.lib;
+part 'part.dart';
+''');
+    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.
+// Comment second.
+
+part of my.lib;
+
+class A {}
+''');
+  }
+
   void test_addSync_BAD_nullFunctionBody() {
     resolveTestUnit('''
 var F = await;
 ''');
     assertNoFix(DartFixKind.ADD_ASYNC);
   }
 
   void test_addSync_blockFunctionBody() {
     resolveTestUnit('''
 foo() {}
@@ skipping 3499 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;
   }
 }