How can I test private methods with DUnit?

Question

I have a class that I am unit testing into with DUnit. It has a number of methods some public methods and private methods.

type
  TAuth = class(TDataModule)
         


        

Answer 1

You don't need to make them public. Protected will do. Then you can subtype the class for unit testing and surface the protected methods. Example:

type
  TAuth = class(TDataModule)
  protected
    procedure MethodIWantToUnitTest;
  public
    procedure PublicMethod;
  end;

Now you can subtype it for your unit test:

interface

uses
  TestFramework, Classes, AuthDM;

type
  // Test methods for class TAuthDM
  TestAuthDM = class(TTestCase)
     // stuff
  end;

  TAuthDMTester = class(TAuthDM)
  public
    procedure MethodIWantToUnitTestMadePublic;
  end;

implementation

procedure TAuthDMTester.MethodIWantToUnitTestMadePublic;
begin
  MethodIWantToUnitTest;
end;

However, if the methods you want to unit test are doing things so intimately with the data module that it is not safe to have them anything but private, then you should really consider refactoring the methods in order to segregate the code which needs to be unit tested and the code which accesses the innards of the data module.