delphiXtreme

I don’t how I didn’t know this until now but it turns out there’s a whole section of DUnit designed to help you test GUI elements. What follows is small write up about how to do it. Read more…

XP dunit, engineering, GUI, TDD, unit testing

This post is a follow up to Busting the great TDD Myth. If you haven’t already read it, please check it out.

Lets review the code from the last post:

function TLogin.GetConnectionString : string;
var
  reg : TRegIniFile;
begin
  reg := TRegIniFile.Create('Software\MyApp');
  Result := reg.ReadString('Database', 'ConnectionString', '');
  FreeAndNil(reg);
end;
 
function TLogin.Execute(const UserName, Password : string) : Boolean;
var
  UserQuery : TADOQuery;
  DBUserPassword : string;
begin
  UserQuery := TADOQuery.Create(nil);
  try
    UserQuery.ConnectionString := GetConnectionString;
    UserQuery.SQL.Text := 'SELECT Password FROM Users WHERE UserName = ' + 
                         QuotedStr(UserName);
    UserQuery.Open;
    DBUserPassword := UserQuery.FieldByName('Password').AsString;
    UserQuery.Free;
    Result := DBUserPassword = Password;
  except
    Result := False;
  end;
end;

Now lets review the problems:

• Hidden dependencies - TLogin does not publish the fact that it relies on a connection to the database and needs a connection string from the registry.
• Mixing concerns - Business logic and object creation occur in the same block of code. This means you can’t test business logic without creating the dependencies.

All of these problems can be summed up as: Too much ceremony and too little essence. What is this class trying to do? Does creating a connection to the database, querying a table and handling exceptions have much to do with the purpose of logging in to the system?

Read more…

XP engineering, patterns, refactoring, TDD, unit testing

WARNING
There’s a lot going on in this article. It is intended to be humorous and slightly inflammatory. It’s also the first of a series. I intend to show you how the average Joe digs himself into a hole and then how to get out. I hope you enjoy the read.

On with the show …

You will not learn what you need to know from a TDD course/book/lecture. When you walk away you will not be able to write better software. You will not be able to test drive all your code in a fully automated test suite. Your expectations will not be met and you will quickly dump the whole concept of Test Driven Development.

It’s true.

The problem has nothing to do with TDD. The problem is that you don’t know how to write better software. TDD will not make you a coding rock star. You will not be the envy of your peers. Your face will not be printed on a t-shirt (I don’t think that’s ever happened but it would be cool).

Read more…

XP engineering, TDD, unit testing