ABAP_to_the_Future

3
ABAP Unit and Test-Driven Development
These variables are then set up during
shown in Listing 3.5.
construction of the object instance, as
METHOD constructor.
CREATE OBJECT mo_logger.
CREATE OBJECT mo_pers_layer
EXPORTING
io_logger = mo_logger " Logging Class
id_valid_on = sy-datum. " Validaty Date
ENDMETHOD.
"constructor
Listing 3.5 Variables Set Up During Construction of Object Instance
However, as you can see, this design does not include any mock objects, which
means that you have no chance to run unit tests against the class. To solve this
problem, you need a way to get the mock objects you created earlier inside the
class under test. The best time to do this is when an instance of the class under
test is being created.
When creating an instance of the class under test, you use a technique called constructor
injection to make the code use the mock objects so that it behaves differently
than it would when running produc tively. With this technique, you still
have private instance variables of the da tabase access classes (for example), but
now you make these into optional import parameters of the constructor. The constructor
definition and implementation now looks like the code in Listing 3.6.
PUBLIC SECTION.
METHODS: constructor IMPORTING
io_pers_layer TYPE REF TO ycl_monster_pers_layer OPTIONAL
io_logger TYPE REF TO ycl_logger OPTIONAL.
METHOD constructor."Implementation
IF io_logger IS SUPPLIED.
mo_logger = io_logger.
ELSE.
CREATE OBJECT mo_logger.
ENDIF.
IF io_pers_layer IS SUPPLIED.
mo_pers_layer = io_pers_layer.
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