Does abap unit testclass can get acces to private methods of classes to tes

Question

Hi,
I want to do a abap unit test inside a user program. the program calls my class and i want some of the methods there to be tested (i.e. db layer, some business logic etc).
My problem is, that I can define unit test very goog on program level or even for public methods of the class.
But what should I do if I want the maybe 3 private methods called by the public method to be tested standalone?
Does anyone have a idea for that?
THX
regards,
Jens

Answer 1

Hello Jens,
you may test private methods with the help of the FRIEND statement. For sample you place a local testclass in the class pool. In order to get friendship you may than use the following sequence of statements.
  class ltc_Repository definition deferred.
  class cl_Global definition local friends ltc_Repository.
  class ltc_Repository                     "#AU Risk Level Harmless
    definition for testing.
    private section.
      methods:
        retrieve_Fails_For_Bad_Key   for testing,
        update_Fails_For_Dup_Key     for testing.
endclass.
or
  interface lif_Unit_Test.
  endinterface.
  class cl_Global definition local friends lif_Unit_Test.
  class ltc_Repository                     "#AU Risk Level Harmless
    definition for testing.
    public section.
      interfaces: lif_Unit_Test.
    private section.
      methods:
        retrieve_Fails_For_Bad_Key   for testing,
        update_Fails_For_Dup_Key     for testing.
endclass.
By this technique you can grant access to private members of the global class to any local class. Without exposing something to the outside world! This code can be placed in the local implementation include of the class pool, or in test class include from release 7.02 onwards.
Using transaction /nABAPHELP provides all details on the FRIEND statement.
Testing private methods can be useful but also tends to result in [fragile tests|http://xunitpatterns.com/Fragile%20Test.html]. That means changes to the implementation may make your test turn red without any violation of the outside contract.
Ciao
  Klaus