delphidunitunit-testing

How to access fields of a TTestCase in a TTestSetup class


I am creating unit tests with DUnit. I have a class that takes quite a long time to initialize.

I derive a class TMyTestSetup from TTestSetup and override its Setup method. This SetUp method is only called once for all the tests in my TTestCase. I put the Initialization process in the TMyTestSetup.SetUp routine to increase performance.

My problem is how can I access the object I want to initialize, which is a field of my TMyTest in the TestSetup class? Is the only way to do it declaring it globally?

untested short example:

TMyTestSetup = class(TTestSetup)
  protected
    procedure SetUp; override;
end;

TMyTest = class(TTestcase)
public
    fTakes4Ever2Init : TInits4Ever2Init;
published
  procedure Test1;     
end;

implementation

procedure TMyTestSetup.Setup;
begin
   // How can I access fTakes4Ever2Init from here?
  fTakes4Ever2Init.create // This is the call that takes long
end;

procedure TMyTest.Test1;
begin
  fTakes4Ever2Init.DoSomething;
end;

initialization
  RegisterTest(TMyTestSetup.Create(TMyTest.Suite));

Solution

  • The trick is to use a public class variable in the TMyTestSetup class.

    Like this (tested and working, complete) example:

    unit TestTestUnit;
    
    interface
    
    uses
      TestFramework, TestExtensions;
    
    type
      TInits4Ever2Init = class
      private
        FValue: integer;
      public
        constructor Create;
        procedure   DoSomething1;
        procedure   DoSomething2;
        procedure   DoSomething3;
      end;
    
    type
      TMyTestSetup = class(TTestSetup)
      public class var
        fTakes4Ever2Init: TInits4Ever2Init;
      protected
        procedure SetUp; override;
      end;
    
      TMyTest = class(TTestCase)
      published
        procedure Test1;
        procedure Test2;
        procedure Test3;
      end;
    
    implementation
    
    uses
      SysUtils, Windows;
    
    { TMyTestSetup }
    
    procedure TMyTestSetup.Setup;
    begin
      fTakes4Ever2Init := TInits4Ever2Init.create; // This is the call that takes long
    end;
    
    { TMyTest }
    
    procedure TMyTest.Test1;
    begin
      TMyTestSetup.fTakes4Ever2Init.DoSomething1;
    end;
    
    procedure TMyTest.Test2;
    begin
      TMyTestSetup.fTakes4Ever2Init.DoSomething2;
    end;
    
    procedure TMyTest.Test3;
    begin
      TMyTestSetup.fTakes4Ever2Init.DoSomething3;
    end;
    
    { TInits4Ever2Init }
    
    constructor TInits4Ever2Init.Create;
    begin
      inherited Create;
    
      // FValue and Format('%p, %d', [Pointer(Self), FValue])) are to confirm
      //   that we are talking to the same object for all the tests,
      //   but that the object is different each time we run the test suite.
    
      Randomize;
      FValue := Random(10000);
    
      OutputDebugString(pAnsiChar('-- TInits4Ever2Init.Create: '
        + Format('%p, %d', [Pointer(Self), FValue])));
    end;
    
    procedure TInits4Ever2Init.DoSomething1;
    begin
      OutputDebugString(pAnsiChar('-- TInits4Ever2Init.DoSomething1: '
        + Format('%p, %d', [Pointer(Self), FValue])));
    end;
    
    procedure TInits4Ever2Init.DoSomething2;
    begin
      OutputDebugString(pAnsiChar('-- TInits4Ever2Init.DoSomething2: '
        + Format('%p, %d', [Pointer(Self), FValue])));
    end;
    
    procedure TInits4Ever2Init.DoSomething3;
    begin
      OutputDebugString(pAnsiChar('-- TInits4Ever2Init.DoSomething3: '
        + Format('%p, %d', [Pointer(Self), FValue])));
    end;
    
    initialization
      RegisterTest(TMyTestSetup.Create(TMyTest.Suite));
    end.
    

    As the comments in the sample indicate, I have used a randomised private variable, and some debug trace output, to confirm that each test call with the test suite is to the same copy of the target object, but that we are getting a different copy of the target object each time the test suite is run.