AUnit - Usefullness of the `Test_Caller` package

Question

There seem to be two different ways to do the same thing when using the AUnit library:

Using the AUnit.Test_Cases.Test_Case type, creating some function tests, then register each tests with the AUnit.Test_Cases.Register_Tests function. We can then add this Test_Case to a Suite using the function AUnit.Test_Suites.Add_Test.

There some example of this:

• the example of the cookbook
• this SO answer
• in the unit test of AdaYaml

(Surprisingly, there no examples using this way in the AUnit repository.)

The other way is to use the AUnit.Test_Fixtures.Test_Fixture type, creating some function tests. These tests can then be added to a Suite using the generic package AUnit.Test_Caller with the functions AUnit.Test_Suites.Add_Test and AUnit.Test_Caller.Create.

I can see way of using Test_Caller in:

• the example of the cookbook
• the examples AUint repo
• in the unit test of json-ada

The only difference I can see is that, when using the AUnit.Test_Cases.Test_Case, you can override the Set_Up_Case, Set_Up, Tear_Down and Tear_Down_Case functions. While with the AUnit.Test_Fixtures.Test_Fixture you can only override the Set_Up and Tear_Down functions (because the tests are not group under a Test_Case).

Appart from that, I don't really see much difference.

So, what is the use of the AUnit.Test_Fixtures.Test_Fixture type with the generic package AUnit.Test_Caller ? Why would use this over the (simpler ?) AUnit.Test_Cases.Test_Case type ?

Every example I have seen in one format can be transformed into the other (the Set_Up_Case and Tear_Down_Case set appart). Could give an example which use one but cannot be done by the other ?