Question

Currently I am using 2-level test hierarchy in DUnit (Test Project -> Test Case -> Test method; see example below). Is it possible to introduce 3rd level or even more levels?

Answer 1

You can use test suites to create as many levels of nesting as you desire. The documentation offers the following example:

The TestFramework unit exposes the TTestSuite class, the class that
implements test suites, so you can create test hierarchies using more
explicit code:

The following function, UnitTests, creates a test suite and adds the
two test classes to it:

function UnitTests: ITestSuite; 
var
  ATestSuite: TTestSuite; 
begin 
  ATestSuite := TTestSuite.create('Some trivial tests'); 
  ATestSuite.addTest(TTestArithmetic.Suite); 
  ATestSuite.addTest(TTestStringlist.Suite);  
  Result := ATestSuite; 
end;

Yet another way to implement the above function would be:

function UnitTests: ITestSuite; 
begin
  Result := TTestSuite.Create(
    'Some trivial tests',
    [TTestArithmetic.Suite, TTestStringlist.Suite]
  );
end;

In the above example, the TTestSuite constructor adds the tests in the passed array to the
suite.

You can register a test suite created in any of the above ways by
using the same call you use to register individual test cases:

initialization    
  RegisterTest('Simple Test', UnitTests);
end.

When run with GUITestRunner, you will see the new hierarchy.