Can I pass a set to a test case in DUnitX?

Question

I'm trying to check the state of an object after running a test. This state is contained in a set. Is it possible to pass the expected state to the test case using DUnitX Attributes, so that I can use the same test for all different inputs?

I tried to pass the set as a constant or as a set, but in my Test routine it always arrives as an empty set.

• Is this possible at all using attributes?
• How would you test if sets are identical?

Example code:

type
  TResult = (resOK,resWarn,resError);
  TResultSet = set of TResult;

const
  cErrWarn : TResultSet = [resWarn];

type
  [TestFixture]
  TMyTest = class(TBaseTest)
    [Test]
    [TestCase('Demo1','InputA,[resWarn]')] // <-- tried as a set
    [TestCase('Demo2','InputB,cErrWarn')]  // <-- tried as a constant

    procedure Test(Input:string; ExpectedResult: TResultSet);
  end;

procedure TMyTest.Test(Input:string; ExpectedResult: TResultSet);
begin
  // ExpectedResult is always the empty set []
  RunTests(MyObject(Input));
  Assert.AreEqual(ExpectedResult, MyObject.ResultSet);
end;

I also tried to define the Expected result as array, but then DUnitX doesn't even call the test anymore. Probably that's just "too much"

    procedure Test(Input:string; ExpectedResult: array of TResult);

The best I could come up with so far was to use the following approach. Take a sample of up to three (insert your favourite integer here...) expected states and check for these separately. This is not really what I was hoping for, but it does the trick.

    procedure Test(Input:string; R1,R2,R3: TResult);

Help is greatly appreciated. :)

Answer 1

You are using TestCaseAttribute to specify the arguments to be passed to your test method. However, it simply does not offer any support for passing sets as arguments. You can see that this is so by looking at the constant Conversions declared in the DUnitX.Utils unit. It maps any conversion to a set to ConvFail.

So, if you want to specify this data using attributes you are going to need to extend the testing framework. You could derive your own descendent from CustomTestCaseSourceAttribute and override GetCaseInfoArray to decode your set arguments. As a crude example, you could use this:

type
  MyTestCaseAttribute = class(CustomTestCaseSourceAttribute)
  private
    FCaseInfo: TestCaseInfoArray;
  protected
    function GetCaseInfoArray: TestCaseInfoArray; override;
  public
    constructor Create(const ACaseName: string; const AInput: string; const AExpectedResult: TResultSet);
  end;

constructor MyTestCaseAttribute.Create(const ACaseName, AInput: string; const AExpectedResult: TResultSet);
begin
  inherited Create;
  SetLength(FCaseInfo, 1);
  FCaseInfo[0].Name := ACaseName;
  SetLength(FCaseInfo[0].Values, 2);
  FCaseInfo[0].Values[0] := TValue.From<string>(AInput);
  FCaseInfo[0].Values[1] := TValue.From<TResultSet>(AExpectedResult);
end;

function MyTestCaseAttribute.GetCaseInfoArray: TestCaseInfoArray;
begin
  Result := FCaseInfo;
end;

You can then add the following attribute to your test method:

[MyTestCase('Demo2', 'InputB', [resWarn])]
procedure Test(Input: string; ExpectedResult: TResultSet);

I've avoided using RTTI here for simplicity, but using RTTI would give you more flexibility. You'd pass the argument as a string, and decode it using RTTI, just as the code in DUnitX does. This means you don't need to write bespoke attributes every time you want to use a set argument.

Even better would be to implement this within DUnitX by extending the Conversions map to cover sets, and submit this as a patch. I'm sure others would find it useful.

Answer 2

Add this conversion function to DUnitX.Utils and put it into the Conversions matrix for tkUString to tkSet (due to limitations of StringToSet and TValue this only works for sets up to 32 elements, for larger sets of up to 256 elements there is more code required though):

function ConvStr2Set(const ASource: TValue; ATarget: PTypeInfo; out AResult: TValue): Boolean;
begin
  TValue.Make(StringToSet(ATarget, ASource.AsString), ATarget, AResult);
  Result := True;
end;

Also you need to use a different separator char for the parameters or it will split them wrong:

[TestCase('Demo1','InputA;[resWarn,resError]', ';')]