Fix for truncated unlinked summaries in ByteStore.

pkg/analyzer/test/src/dart/analysis/file_state_test.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:typed_data';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
@@ skipping 583 matching lines @@
     print(222);
   }
 }
 ''');
     bool apiSignatureChanged = file.refresh();
     expect(apiSignatureChanged, isFalse);
 
     expect(file.apiSignature, signature);
   }
 
+  test_store_zeroLengthUnlinked() {
+    String path = _p('/test.dart');
+    provider.newFile(path, 'class A {}');
+
+    // Get the file, prepare unlinked.
+    FileState file = fileSystemState.getFileForPath(path);
+    expect(file.unlinked, isNotNull);
+
+    // Make the unlinked unit in the byte store zero-length, damaged.
+    byteStore.put(file.test.unlinkedKey, <int>[]);
+
+    // Refresh should not fail, zero bytes in the store are ignored.
+    file.refresh();
+    expect(file.unlinked, isNotNull);
+  }
+
   test_subtypedNames() {
     String path = _p('/test.dart');
     provider.newFile(path, r'''
 class X extends A {}
 class Y extends A with B {}
 class Z implements C, D {}
 ''');
     FileState file = fileSystemState.getFileForPath(path);
     expect(file.referencedNames, unorderedEquals(['A', 'B', 'C', 'D']));
   }
@@ skipping 196 matching lines @@
   String _p(String path) => provider.convertPath(path);
 
   static String _md5(String content) {
     return hex.encode(md5.convert(UTF8.encode(content)).bytes);
   }
 }
 
 class _GeneratedUriResolverMock extends Mock implements UriResolver {}
 
 class _SourceMock extends Mock implements Source {}