In this article we will talk about the file systems and files, but the  most attention will be focused on the key points of testing of software that works with NTFS and FAT file systems.

  At the end we will give our check list for testing of software, working  with the FAT and NTFS file systems - we hope that it will help you in  development of testing plan for your software.

Written by:
Tatyana Kit, QA Special_ist; Natalya Novotnaya, Team Leader of Testing Team,
ApriorIT Inc. 

Table  of Content

  1.      Introduction
  2.      Testing  of applications working with the file systems
  2.1.       Creation of the file system
  2.2.       FilesFolders and work with them
  2.3.       Properties of files and folders
  2.4.       NTFS Links.
  2.5.       NTFS Alternative Data Streams (ADS)
  3.      Additional  points from general testing principles.
  4.      Conclusion.
  Appendix1        Check List for testing.
 

1. Introduction

File system is a part of the operating system. All necessary information  is stored in files which we work with. So corrupted or disappeared without  trace file makes us, at least, not very happy.   Thus, if the developed software does not handle the storing of user  information then it is synonymous to failure.

  In this article we will talk about the file systems and files, but the  most attention will be focused on the key moments of testing of software that  works with them.

  At the end we will give our check list for testing of software, working  with the FAT and NTFS file systems - we hope that it will help you in  development of testing plan for your software.

 

For example:

 

   
• applications that create disk image
   
• applications that mount disk image as a driver and  allow user to work with it as with the real drive
   
• applications that analyze information on the disk
   
• applications that archive/encrypt data.
 

 

2. Testing of applications working with the file  systems

In the internet - and not only there - you can find a lot of sources on  the file systems describing their type, structure, history and features.  Therefore let’s believe that all readers have such knowledge.

  First let’s define the basic principle in our testing as following: the  result of all actions must be the same to the one obtained when the operating  system works without us. We can work better, but never worse.

  As experience shows, the operations are the first that occur when we  start talking about the file systems and files. It is not difficult to list  them: to create, copy, move, rename, modify and delete. Exactly this list will  help us in testing.

2.1 Creation of the file system

Our testing starts where the file system is created, namely in the  moment of disk formatting. During this process user chooses the system to be  created: FAT or NTFS. Pay attention that all of disks are formatted with a  standard (by default) cluster size.

   

  Figure 1 Formatting dialog form

  Thus, we must check:

   

     
• Formatting of empty disk with the new file system FATNTFS.
     
• Formatting of not empty disk with the new file system FAT  NTFS. I.e. we already had the file system and files on a disk before formatting.
     
• Formatting with the non-standard size of a cluster. It’s  important when we choose file size for testing of the NTFS file system. In fact  if the file size will be less than 2 clusters (cell of MFT table) then the file  will be fully placed in MTF table. And so we won’ be able to check up work on  difficult transitions between the disk clusters.
     
• Fast formatting function for FATNTFS.
     
• Option of information compression during the  formatting in NTFS systems (economy of disk space).
     
•  Change  properties of data compression for NTFS file systems on the fly in the disk  properties:
   

  Figure 2 NTFS disk properties form

  This option also creates additional test surroundings  - compressed not compressed NTFS disk - for testing of file operations.

     
• Correctness of volume identifier, sizes of used and  free spaces, capacity.

2.2 FilesFolders and work  with them

Verification of file operations is the essential part of testing of  software with the file systems. We will mark that talking about the file  systems and files we do not mention the folders but always have them in mind.

  There are not a lot of file operation: it’s just reading and writing.  But they look differently for user: create, copy, move, rename and delete a  file(s) folder(s).

  Therefore we will test:

   

     
• Creation of a file by means of explorer or application  menu. Pay attention that an application usually creates file not with the  Create function but with the Save one. Another interesting moment is  installation when we specify our disk for the software. After that the  application should not only be installed but also start and work.
     
• Copying Moving files and folders within the one disk and  to the other one.
     
• Option to rename a fileolder. Especially when it is  locked by other applications.
     
• Deleting file to the recycle bin and directly. Naturally  we should check that after restoring from the bin files are still valid.
   

Take into account  (!) the fact that an  operation depends on the application that executes it, therefore provide yourself  with a few file managers, not only Windows explorer.

  Let’s continue testing. Each file has a lot of properties. And if not  all then many of them should be checked.

2.3 Properties of files and folders

Properties of  files and folders have a lot in common, but there are differences. We test:

   

     
• Work with the files/ folders with the simple names:  lines of the defined format. Here it is the set of allowed characters.
   

For example: Test1.txt

     
• Empty line as a filename.
     
• Long name that has more than 8 characters and includes  blanks.

For example: Testing  is the most exiting activities in the World.txt

   

     
• Name containing the special characters: /:*? ” <>|
   

Now let us take into account a specialty of folders: there  can be subfolders. So we get additional tests on work with the subfolders. But what  number of subfolders will be enough? About 10 must be enough for an ordinary  user, but sometimes there are exceptions. User profile can tell more about it.  

   

     
• We check up work with the folder nesting  equal to 10 subfolders.
     
• Check file creation/modification date and time. Size  on disk and the real file size should be checked too.
   

  Figure 3 File properties form

   

     
• Also there are file attributes: readonly, hidden,  system and additional attributes (compressed file, encrypted file, indexation  attributes).
   

  Figure 4 Advanced file properties

   

     
• File icons should be shown as they are defined in the operating  system. It’s user-friend requirement.
     
•  Talking about  icons, we step up to the file types. It’s very important aspect of testing,  because it is necessary to check the different types of files. You can start  with the most popular ones, for example ms office, pdf, dvju, exe files, installations  and so on.
   

2.4 NTFS Links.

We start this section with a small piece of theoretical material.

  The Windows kernel supports the  followings types of links:

 
• Hard Links. Available since Windows NT4. They can be       created only to files.
 
• Junction Points is symbolic links. Available since Windows 2000.       They can be created only to directories.
 
• Symbolic Links. Available since Windows Vista. They can be       created both to folders and files.

HardLink is simply another record in the  folder for this file.

  When hard link is created the file is not copied  physically, and only appears under another name or in another place, while its  old name and location remain untouched. After this moment hard link is the same  to the primary record in the folder. The only difference is that the short file  name is not created for the hard link, therefore it is not visible from the DOS  programs.

  When a size or file date/time changes all  corresponding records in folders are refreshed automatically. At the delete of  file he does not retire physically until all of hard connections, indicative on  him, will not be remote. The order of their delete of value does not have. After  deleting the hard link to the recycle bin the number of links for the file  remains the same.

  Creating hard links is possible only in the same  partition where the initial file is located.

  NTFS since 5.0 version (Windows 2000/XP) supports symbolic  links (SymLink). Folder symbolic links in Windows 2000/XP are known as «Directory  junctions»  - the technology that enables  to represent any local folders to any other local folders. For example, if the  folder D:SYMLINK is linked to C:WINNTSYSTEM32 as its target, then the  program addressing to D:SYMLINKDRIVERS will actually address to C:WINNTSYSTEM32DRIVERS.

  Unlike hard links symbolic links not necessary address  to the same partition. Thus the character links can be broken if we change the  structure of partitions.

  Even Windows explorer is not able to work correctly with  everything supported by the kernel. Therefore when testing the applications taking  disk images and also different file managers you should check them for work  with ntfs links.

  Usually there are no problems with hard links, however  symbolic links sometimes behave rather strange.

  When testing the applications with built-in file  managers you should check:

   

     
• If the symbolic links are shown correctly.
     
• If the transition by the symbolic links is performed  correctly. As soon as junction point can be created in such way that it will  refer to itself or to the paternal directory, it is necessary to test such  cases separately. Many known file managers can fall into recursion when  attempting to follow such links.
     
• If the size of directory containing links is detected correctly.  And problems here can be both with symbolic and hard links.
     
• If the links are copied correctly. The correct behavior  in this case is to make the copy of link, but not copy of the folder which it  refers to. The case when the copying is performed to another hdd should be also  considered. Another case is when folder contains broken links – you should  check if it can be opened.
     
• If the links are correctly deleted. Some file managers  delete not only the link but also the directory which it refers to. In this  case there is the real risk to lose information. Most likely there will not be  such problem for the hard links but nevertheless you should check that it’s  impossible to delete the file before all its links will be deleted. There can  be also a case to check if user can delete file link when file is opened by  another link.
     
• If the links are correctly moved.  Actually moving consists of copying and deleting  but it’s always better to check one more time.
   

When you test applications that create disk images or mount them you  should check them for link cases too. Created and mounted image should show  links correctly, go to the corresponding folders following the links, including  recursive ones, and should not crash at the broken links.

  When you test archiving and encrypting applications you should also  check them with the folder containing the usual links, recursive and broken  ones. The application should not crash or hang while achieving/encrypting. And  links should remain working after extracting/decoding to the same partition.

  We can recommend the following software for working with the NTFS links:

  Utilities from Microsoft:

  mklink command was  added in Windows Vista to make symbolic and hard links. Syntax and examples can  be found here: http://technet.microsoft.com/en-us/library/cc753194(WS.10).aspx

  In Windows 2000 and higher Hard links can be created  from command line by the command fsutil and its parameter hardlink.  Description can be found here: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/fsutil.mspx?mfr=true

  Microsoft Windows Resource Kit can be used to work with junction points http://www.microsoft.com/downloads/details.aspx?familyid=9d467a69-57ff-4ae7-96ee-b18c4790cffd&displaylang=en

Linkd.exe, Mountvol.exe and Delrp.exe utilities might be required for  this kit – see description  and examples here: http://support.microsoft.com/kb/205524

You can also use junction.exe utility from Microsoft to work with  junction points. Its advantage is that you don’t have to download the whole Resource  Kit. Download and description here: http://technet.microsoft.com/en-us/sysinternals/bb896768.aspx

Extensions for Explorer

Additionally to all mentioned console utilities there  are a number of free programs that integrate in Windows Explorer add their  commands to the pop-up menus and allow to work with links of all types. In  addition, they hook the Explorer calls providing normal moving/copying/deleting  of the created links.

NTFS Link:  http://elsdoerfer.name/=ntfslink

NTFS Links: http://alax.info/blog/ntfslinks

Personally we recommend Link Shell  Extension – it has wide functionality and detailed description: http://schinagl.priv.at/nt/hardlinkshellext/hardlinkshellext.html

Other utilities

FAR file manager (http://www.farmanager.com/) supports Hard  Links and Junction Points. You can use Alt-F6 combination to create links.

Junction Link  Magic — easy to use free  program with gGUI to work with links except for Hard links. See it here: http://www.rekenwonder.com/linkmagic.htm

2.5 NTFS Alternative Data Streams (ADS)

The alternative data streams appeared in Windows NT together with NTFS file  system. It was done for providing of compatibility with HFS (old file system of  Macintosh), which divided each file into the file of data and file of  resources. 

  Windows Explorer and other applications work with a standard stream and  cannot read information from the alternative streams. Alternative streams are  not shown in the Explorer; their size is not counted in the file size. When you  copy a file to the disk with FAT system or to the network share alternative  streams are not copied. They are chopped off also if you upload a file on the  web server or attach it to the email.

  Testing

  To date not everybody knows about existence of ADS. Meantime, they must  be taken into account when testing applications that make disk images or perform  search of hidden information.

  While testing file managers you should check:

 
   
     
1. If the file with ADS is correctly opened
     
2. Whether ADS are kept after a file is copied on NTFS partition
     
3. If the size of file with ADS is correctly counted
     
4. If a file is opened correctly after ADS are deleted.
   
 

Testing of applications that make disk images (and  also archiving and encrypting programs) requires checking that they correctly  add files with ADS in the image, i.e. after mounting (extraction/decoding) of  this image it is possible to browse data in the alternative streams.

    Creation of test data

  We’ll use command line to create  test file. First let’s create a file in the standard stream:

 

  C:>echo Visible text>file.txt  C:>type file.txt    Visible text

 

This file can be opened in Notepad  and you can see text there: Visible text. Now we can create an alternative  stream in this file. To address to the alternative stream colon operator is  used:

 

  C:>echo you cannot see this text>file.txt:altstream.txt

dir, type commands and Windows Explorer  won’t help you to see the content of alternative stream. Instead we will use  more command:

  C:>more < file.txt:altstream.txt  You cannot see this text

It is also possible to see the content  of alternative stream in the Notepad:

  C: notepad file.txt:altstream.txt

See the size of file.txt – it is  14 byte, i.e. content of alternative stream is not counted in the file size.

  It is possible to create a few  alternative streams for each file.

An alternative stream can be  attached not only to the file but also to the folder.

  Let’s create a folder:

 

  C:>md folder  

Attach some text in the  alternative stream:

  C:>cd folder  C: folder >echo Hidden  text >:altstream.txt

If we browse the content of the folder  we can’t see hidden text:

  C: folder >dir  Volume in drive C has no label.  Volume Serial Number is DC9B-ABBE   Directory of C:older  07/04/2009 10:19 AM .  07/04/2009 10:19 AM .  0 File(s) 0 bytes2 Dir(s)  12,253,208,576 bytes free

The hidden text can be seen in  the Notepad:

  C:older>notepad  : altstream.txt

To delete alternative streams from the file by means of standard Windows  tools you can move the file to the disk with the FAT file system.

  Thus we can create test information as alternative streams attached to  the files and folders and browse them by means of standard Windows tools.

  If the name of the stream is unknown we cannot address to it. To search for  all streams of the file or folder Microsoft offers the simple console utility Streams.exe.  To download it and learn syntax go here: http://technet.microsoft.com/en-us/sysinternals/bb897440.aspx

  There is also a number of GUI of utilities to work with streams.  Unfortunately, basic functionality of these utilities includes only scanning a  file or folder to discover ADS and deleting some of them. Not all of such  programs even show content of the streams. So they are not very useful for  testing purposes.

  We can recommend ADSTools (http://www.brothersoft.com/adstools-60658.html). This utility enables to create streams, edit,  rename, delete, scan files and folders to discover ADS and has a number of  other features.

   FAR plug-in to work with ADS is  also rather useful. It enables  to create  streams for files and folders, browse streams of any file, delete streams etc.  This plug-in is free: http://plugring.farmanager.com/cgi-bin/downld.cgi?Lang=Eng&Draw=List&Sort=Date&SelectCateg=Addons&Select=PlugIn&SelectPlugIn=234&SelectAuthor=0&SelectOther=1&SearchText=

3. Additional points from general testing principles

And a few words in conclusion about general things.

   

     
1. Check your application not only for the correct work  but also for performance. Time spent on file operations should be adequate to  the input data. For example creation of empty file for 2 minutes is obviously  not adequately and confusing.
     
2. You should remember that your application is a guest of  the operating system and so it must behave properly. It especially applies to  the memory and memory leaks – so measure the amount of memory used during the work  with files. You should pay attention on two aspects. First is its optimal amount:  using 100 MB for the zero file is obviously strange. And the second is that  after closing the application memory should be returned to the proprietor, i.e.  to the operating system.
     
3. Do not forget also that the file system is a part of  the operating system, and so standard things should work such as hotkeys.
   

4. Conclusion.

This theme - testing of applications workings with the file systems - is  very interesting, and it’s much wider than we showed in this article. We will try  to continue this theme in the following articles.

  On this point we say good-bye. Also we’ve added some templates of check lists  which you can use for your testing.

Appendix1: Check List for testing

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           

Create file system
Test name			Test Result
Formatting    empty disk with FAT file system    and default cluster size			0
Formatting    empty disk with NTFS file system    and default cluster size			x
Formatting FAT disk with FAT file system and    default cluster size			0
Formatting NTFS disk with FAT file system and    default cluster size			0
Formatting FAT disk with NTFS  file system and default cluster size
Formatting NTFS disk with NTFS  file system and default cluster size
Formatting    disk with FAT file system and custom cluster size
Formatting    disk with NTFS file system and custom cluster size
Quick    formatting with FAT file system
Quick    formatting with NTFS file system
Format NTFS with compressing data
Compress data for exist NTFS disk
Validate NTFS disk properties: Name, Capacity,    etc
Validate FAT disk properties: Name, Capacity,    etc
Files Folders and    work with them
Test name	NTFS compressed	NTFS not compressed		FAT
Create file from explorer menu	0	0		0
Save as from application file to disk	0	x		0
Install Application into disk
Extract archive to disk
Copy file    (s) to another folder to the same    disk
Copy folder    (s) to another folder to the same    disk
Copy file    (s) to another folder to the another    disk
Copy folder    (s) to another folder to the another    disk
Copy with    explorer
Copy    files with another file manager
Move file    (s) to another folder to the same    disk
Move folder (s) to another folder to the same disk
Move file (s) to another folder to the another disk
Move folder (s) to another folder to the another disk
Move with    explorer
Move    files with another file manager
Rename file in explorer
Rename Folder in explorer
Rename file in another file manager
Rename Folder in another file manager
Delete file (s) into Recycle
Delete folder (s) into Recycle
Restore file (s) from Recycle
Restore folder (s) from Recycle
Permanent delete file (s)
Permanent delete folder (s)
Properties file (s) and    Folder (s)
Test name	NTFS compressed	NTFS not compressed		FAT
File type, for example txt       (this block is repeated for all file types    that included  into testing data)
Enter correct name of the file, for example    test1.txt	0	0		0
Enter empty name of the file	0	x		0
Enter long name with space of the file, for    example Testing is the most exited activities in the World.txt
Enter file name with forbidden symbols /:*?    ” <>|
Validate dates of the file (creation, modified,    accessed)
Validate size of the file (size, size on disk)
Validate attributes of the file (read-only, hidden)
Validate attributes of the file (read-only, hidden)
Validate advanced attributes of the file (Archive and Index attributes,    Compress or Encrypted attributes)
Validate    correct icon display for file
Folder
Enter correct name of the folder	0	x		0
Enter empty name of the folder
Enter long name with space of the folder
Enter folder name with forbidden symbols /:*?    ” <>|
Create folder structure with 10 level of    subfolders
Validate dates of the folder (created)
Validate size of the folder (size, size on disk,    Contains)
Validate attributes of the folder (read-only, hidden)
Validate advanced attributes of the folder (Archive and Index attributes,    Compress or Encrypted attributes)
Validate    correct icon display for folder