When testing applications, you may need to verify different files. This is often done to make sure that the application under test generates correct output data (for example, a list of orders).

Quite often the generated files contain information that is modified from one copy to another, whereas the major information remains the same. For example, the current date or time, document’s ID, owner name and so on. The byte-by-byte comparison performed by the file checkpoints or by the Compare Files operation and the Files.Compare method is ineffective, since the compared files are not identical.

As a solution, you can exclude those variable parts from verification. The general idea is to find the altering fragment and replace it with the unified fragment.

You can perform this task by writing special script code that will use regular expression for verification.

Note: JavaScript, JScript, Python, VBScript, C#Script and C++Script have internal support for regular expressions. To learn how to use regular expressions in these scripting languages, read the Introduction to Regular Expressions (Scripting) article in the MSDN library. For DelphiScript, regular expressions are implemented via the RegExpr object, which is provided by the HISUtils plugin (installed and enabled by default). This object can also be used in JavaScript, JScript, Python, VBScript, C#Script and C++Script code.

The code below demonstrates how to use regular expressions to compare text files ignoring the date/time stamps.

JavaScript

function CompareFiles(fileName1, fileName2)
{
  var fso, file1, file2, regEx;
  var fileText1, fileText2, newText1, newText2;
  const ForReading = 1;

  // Creates the FileSystemObject object
  fso = getActiveXObject("Scripting.FileSystemObject");

  // Reads the first text file
  file1 = fso.OpenTextFile(fileName1, ForReading);
  fileText1 = file1.ReadAll();
  file1.Close();

  // Reads the second text file
  file2 = fso.OpenTextFile(fileName2, ForReading);
  fileText2 = file2.ReadAll();
  file2.Close();

  // Specifies the regular expression pattern for the date/time mask
  // MM/DD/YYYY HH:MM:SSLL (for example: 4/25/2006 10:51:35AM)
  regEx = /\d{1,2}.\d{1,2}.\d{2,4}\s\d{1,2}:\d{2}:\d{2}\w{2}/gim;

  // Replaces the text matching the specified date/time format with <ignore>
  newText1 = fileText1.replace(regEx, "<ignore>");
  newText2 = fileText2.replace(regEx, "<ignore>");

  // Compares the text
  return equal(newText1, newText2);
}

function Main()
{
  var fileName1 = "d:\\text1.txt";
  var fileName2 = "d:\\text2.txt";

  if (CompareFiles(fileName1, fileName2))
    Log.Message("The files are equal");
  else
    Log.Error("The files are different");
}

JScript

function CompareFiles(fileName1, fileName2)
{
  var fso, file1, file2, regEx;
  var fileText1, fileText2, newText1, newText2;
  var ForReading = 1;

  // Creates the FileSystemObject object
  fso = new ActiveXObject("Scripting.FileSystemObject");

  // Reads the first text file
  file1 = fso.OpenTextFile(fileName1, ForReading);
  fileText1 = file1.ReadAll();
  file1.Close();

  // Reads the second text file
  file2 = fso.OpenTextFile(fileName2, ForReading);
  fileText2 = file2.ReadAll();
  file2.Close();

  // Specifies the regular expression pattern for the date/time mask
  // MM/DD/YYYY HH:MM:SSLL (for example: 4/25/2006 10:51:35AM)
  regEx = /\d{1,2}.\d{1,2}.\d{2,4}\s\d{1,2}:\d{2}:\d{2}\w{2}/gim;

  // Replaces the text matching the specified date/time format with <ignore>
  newText1 = fileText1.replace(regEx, "<ignore>");
  newText2 = fileText2.replace(regEx, "<ignore>");

  // Compares the text
  return (newText1 == newText2);
}

function Main()
{
  var fileName1 = "d:\\text1.txt";
  var fileName2 = "d:\\text2.txt";

  if (CompareFiles(fileName1, fileName2))
    Log.Message("The files are equal");
  else
    Log.Error("The files are different");
}

Python

def CompareFiles(fileName1, fileName2):
  ForReading = 1

  # Creates the FileSystemObject object
  fso = Sys.OleObject["Scripting.FileSystemObject"]

  # Reads the first text file
  file1 = fso.OpenTextFile(fileName1, ForReading)
  fileText1 = file1.ReadAll()
  file1.Close()

  # Reads the second text file
  file2 = fso.OpenTextFile(fileName2, ForReading)
  fileText2 = file2.ReadAll()
  file2.Close()

  # Specifies the regular expression pattern for the date/time mask
  # MM/DD/YYYY HH:MM:SSLL (for example: 4/25/2006 10:51:35AM)
  regEx = "/\d{1,2}.\d{1,2}.\d{2,4}\s\d{1,2}:\d{2}:\d{2}\w{2}/gim"

  # Replaces the text matching the specified date/time format with <ignore> 
  newText1 = fileText1.replace(regEx, "<ignore>")
  newText2 = fileText2.replace(regEx, "<ignore>")

  # Compares the text
  return (newText1 == newText2)

def Main():
  fileName1 = "d:\\text1.txt"
  fileName2 = "d:\\text2.txt"

  if (CompareFiles(fileName1, fileName2)):
    Log.Message("The files are equal")
  else:
    Log.Error("The files are different")

VBScript

Function CompareFiles(fileName1, fileName2)
  Dim fso, file1, file2, regEx
  Dim fileText1, fileText2, newText1, newText2
  Const ForReading = 1

  ' Creates the FileSystemObject object
  Set fso = CreateObject("Scripting.FileSystemObject")

  ' Reads the first text file
  Set file1 = fso.OpenTextFile(fileName1, ForReading)
  fileText1 = file1.ReadAll
  file1.Close

  ' Reads the second text file
  Set file2 = fso.OpenTextFile(fileName2, ForReading)
  fileText2 = file2.ReadAll
  file2.Close

  ' Creates the regular expression object
  Set regEx = New RegExp

  ' Specifies the pattern for the date/time mask
  ' MM/DD/YYYY HH:MM:SSLL (for example: 4/25/2006 10:51:35AM)
  regEx.Pattern = "\d{1,2}.\d{1,2}.\d{2,4}\s\d{1,2}:\d{2}:\d{2}\w{2}"
  regEx.IgnoreCase = True
  regEx.Global = True

  ' Replaces the text matching the specified date/time format with <ignore>
  newText1 = regEx.Replace(fileText1, "<ignore>")
  newText2 = regEx.Replace(fileText2, "<ignore>")

  ' Compares the text
  CompareFiles = (newText1 = newText2)
End Function

Sub Main
  Dim fileName1, fileName2

  fileName1 = "d:\text1.txt"
  fileName2 = "d:\text2.txt"

  If CompareFiles(fileName1, fileName2) Then
    Log.Message("The files are equal")
  Else
    Log.Error("The files are different")
  End If
End Sub

DelphiScript

function CompareFiles(fileName1, fileName2);
const
  ForReading = 1;
var
  fso, regEx;
  file1, file2;
  fileText1, fileText2, newText1, newText2;
begin
  // Creates the FileSystemObject object
  fso := Sys.OleObject('Scripting.FileSystemObject');

  // Reads the first text file
  file1 := fso.OpenTextFile(fileName1, ForReading);
  fileText1 := file1.ReadAll;
  file1.Close;

  // Reads the second text file
  file2 := fso.OpenTextFile(fileName2, ForReading);
  fileText2 := file2.ReadAll;
  file2.Close;

  // Creates the regular expression object
  regEx := HISUtils.RegExpr;

  // Specifies the pattern for the date/time mask
  // MM/DD/YYYY HH:MM:SSLL (for example: 4/25/2006 10:51:35AM)
  regEx.Expression := '(?i)\d{1,2}.\d{1,2}.\d{2,4}\s\d{1,2}:\d{2}:\d{2}\w{2}';

  // Replaces the text matching the specified date/time format with <ignore>
  newText1 := regEx.Replace(fileText1, '<ignore>');
  newText2 := regEx.Replace(fileText2, '<ignore>');

  // Compares the text
  Result := (newText1 = newText2);
end;

procedure Main;
var
  fileName1, fileName2;
begin
  fileName1 := 'd:\text1.txt';
  fileName2 := 'd:\text2.txt';

  if CompareFiles(fileName1, fileName2) then
    Log.Message('The files are equal')
  else
    Log.Error('The files are different');
end;

C++Script, C#Script

function CompareFiles(fileName1, fileName2)
{
  var fso, file1, file2, regEx;
  var fileText1, fileText2, newText1, newText2;
  var ForReading = 1;

  // Creates the FileSystemObject object
  fso = new ActiveXObject("Scripting.FileSystemObject");

  // Reads the first text file
  file1 = fso["OpenTextFile"](fileName1, ForReading);
  fileText1 = file1["ReadAll"]();
  file1["Close"]();

  // Reads the second text file
  file2 = fso["OpenTextFile"](fileName2, ForReading);
  fileText2 = file2["ReadAll"]();
  file2["Close"]();

  // Specifies the regular expression pattern for the date/time mask
  // MM/DD/YYYY HH:MM:SSLL (for example: 4/25/2006 10:51:35AM)
  regEx = /\d{1,2}.\d{1,2}.\d{2,4}\s\d{1,2}:\d{2}:\d{2}\w{2}/gim;

  // Replaces the text matching the specified date/time format with <ignore>
  newText1 = fileText1["replace"](regEx, "<ignore>");
  newText2 = fileText2["replace"](regEx, "<ignore>");

  // Compares the text
  return (newText1 == newText2);
}

function Main()
{
  var fileName1 = "d:\\text1.txt";
  var fileName2 = "d:\\text2.txt";

  if (CompareFiles(fileName1, fileName2))
    Log["Message"]("The files are equal");
  else
    Log["Error"]("The files are different");
}

Verifying Files With Variable Parts

See Also