third_party/WebKit/LayoutTests/fast/filesystem/resources/file-writer-sync-truncate-extend.js

   1 if (this.importScripts) {
   2     importScripts('../resources/fs-worker-common.js');
   3     importScripts('../../../resources/js-test.js');
   4     importScripts('../resources/fs-test-util.js');
   5     importScripts('../resources/file-writer-utils.js');
   6 }
   7
   8 description("Test using FileWriterSync.truncate to extend a file.");
   9
  10 // Start with an empty FileSystem.
  11 var fileSystem = webkitRequestFileSystemSync(this.TEMPORARY, 100);
  12 removeAllInDirectorySync(fileSystem.root);
  13
  14 // Prepare a file with sample contents.
  15 var entry = fileSystem.root.getFile('a', {create:true, exclusive:true});
  16 var writer = entry.createWriter();
  17 assert(!writer.position);
  18 var testData = "test data";
  19 writer.write(new Blob([testData]));
  20 assert(writer.length == testData.length);
  21 assert(writer.position == writer.length);
  22
  23 // Extend the file via truncate.
  24 var extensionLength = 10;
  25 writer.truncate(writer.length + extensionLength);
  26
  27 // Verify the contents.
  28 assert(writer.length == testData.length + extensionLength);
  29 assert(writer.position == testData.length);
  30 var file = entry.file();
  31 var reader = new FileReaderSync();
  32 var contents = reader.readAsBinaryString(file);
  33 var i;
  34 for (i = 0; i < testData.length; ++i)
  35     assert(contents.charCodeAt(i) == testData.charCodeAt(i));
  36 for (; i < writer.length; ++i)
  37     assert(!contents.charCodeAt(i));
  38
  39 testPassed("Truncate extension verified.");
  40 finishJSTest();