METHOD simple_configuration.

    DATA:  lo_currency_converter_double TYPE REF TO      if_td_currency_converter,
          lo_expense_manager          TYPE REF TO      cl_td_expense_manager,
          lv_total_expense            TYPE              i.

*create test double object
    lo_currency_converter_double ?= cl_abap_testdouble=>create( ‘if_td_currency_converter’ ).

*configuration for stubbing method ‘convert’:

*step 1: set the desired returning value for the method call
    cl_abap_testdouble=>configure_call( lo_currency_converter_double )->returning( 80 ).

*step 2: specifying which method should get stubbed
    lo_currency_converter_double->convert(
          EXPORTING
        amount          = 100
        source_currency = ‘USD’
        target_currency = ‘EUR’
        ).

*injecting the test double into the object being tested
    CREATE OBJECT lo_expense_manager EXPORTING currency_converter = lo_currency_converter_double.

*add one expense item
    lo_expense_manager->add_expense_item(
          EXPORTING
        description  = ‘Line item 1’
        currency_code = ‘USD’
        amount        = ‘100’
        ).

*actual method call
    lv_total_expense = lo_expense_manager->calculate_total_expense( currency_code = ‘EUR’ ).

*assertion
    cl_abap_unit_assert=>assert_equals( exp = 80 act = lv_total_expense ).

  ENDMETHOD.