delphiunit-testingdunit

How can I test private methods with DUnit?


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)
  private
    procedure PrivateMethod;
  public
    procedure PublicMethod;
  end;

In order to write a unit test for this class I have to make all the methods public.

Is there a different way to declare the private methods so that I can still test them but they are not public?


Solution

  • 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.