ABAP_to_the_Future

3
ABAP Unit and Test-Driven Development
Step Three: Calling the Production Code to Be Tested
The time has come to actually invoke th e code to be tested: you are calling precisely
one method or other type of routine, you pass in your hard-coded dummy
values, you call the routine, and you usua lly get some sort of result back. The
important thing is that the routine being called does not know it is being called
from a test method; the business logic behaves exactly as it would in production,
with the exception that when it interacts with the database or another external
system it is really dealing with mock classes.
In this example, when you pass in the hard-coded input data, the real business logic
will be executed, and a list of monster components is passed back (Listing 3.17).
"WHEN..........................
METHOD when_bom_is_calculated.
mo_class_under_test->simulate_bom(
EXPORTING is_bom_input_data = ms_input_data
IMPORTING et_bom = mt_bom_data ).
ENDMETHOD."when_bom_is_calculated
Listing 3.17 Calling the Production Code to Be Tested
The method that calls the code to be tested should be very short—for example, a
call to a single function module or a method—for two reasons:
왘 Clarity
Anyone reading the test code should be able to tell exactly what the input data
is, what routine processes this data, and what form the result data comes back
in. Calling several methods in a row distracts someone reading the code and
makes them have to spend extra time working out what is going on.
왘 Ease of maintenance
You want to hide the implementation de tails of what is being tested from the
test method; this way, even if those implementation details change, the test
method does not need to change.
For example, in a procedural prog ram, you may call two or three PERFORM statements
in a row when it would be better to do a call to a single FORM routine—so
that if you were to add another FORM routine in the real program, you wouldn’t
have to go and add it to the test method as well. With procedural programs, it
would be good if you had a signature with the input and output values, but a lot
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