Using the correct method call syntax to request a unit test assertion
This blog represents part 6 of this 10-part series Getting acquainted with automating ABAP unit testing.
Part 5 – Fix the production code bug identified by the first unit test
To recap from the preceding blog, we corrected the bug exposed by a failing unit test. Now the unit test passes and the program, when executed, produces an ALV classic list report instead of issuing an error message, though the rows appearing in the report do not necessarily match the value specified on the initial selection screen. Here is the source code as we left it in the previous blog:
program. *---------------------------------------------------------------------- * Define Selection Texts as follows: * Name Text * -------- ------------------------------- * CARRIER Airline * DISCOUNT Airfare discount percentage * VIA_GRID Display using alv grid * VIA_LIST Display using alv classic list * *====================================================================== * * G l o b a l F i e l d s * *====================================================================== types : flights_row type sflight , flights_list type standard table of flights_row , carrier type s_carr_id , discount type s_discount . constants : flights_table_name type tabname value 'SFLIGHT' . data : flights_count type int4 , flights_stack type flights_list . *====================================================================== * * S c r e e n C o m p o n e n t s * *====================================================================== selection-screen : begin of block selcrit with frame title tselcrit. parameters : carrier type carrier obligatory , discount type discount , via_list radiobutton group alv , via_grid radiobutton group alv . selection-screen : end of block selcrit. *====================================================================== * * C l a s s i c P r o c e d u r a l E v e n t s * *====================================================================== initialization. tselcrit = 'Selection criteria' ##NO_TEXT. at selection-screen. if sy-ucomm ne 'ONLI'. return. endif. " Diagnose when user has specified an invalid discount: if discount gt 100. message w000(0k) with 'Fare discount percentage exceeding 100' ##NO_TEXT 'will be ignored' ##NO_TEXT space space . endif. " Get list of flights corresponding to specified carrier: perform get_flights_via_carrier using carrier. " Diagnose when no flights for this carrier: if flights_count le 00. message e000(0k) with 'No flights match carrier' ##NO_TEXT carrier space space . endif. start-of-selection. end-of-selection. perform present_report using discount via_grid. *====================================================================== * * S u b r o u t i n e s * *====================================================================== form get_flights_via_carrier using carrier type carrier. clear flights_stack. if carrier is not initial. try. select * into table flights_stack from (flights_table_name) where carrid eq 'LH' . catch cx_root ##NO_HANDLER ##CATCH_ALL. " Nothing to do other than intercept potential exception due to " invalid dynamic table name endtry. endif. describe table flights_stack lines flights_count. endform. form present_report using discount type discount via_grid type xflag. perform show_flights_count. perform show_flights using discount via_grid. endform. form show_flights_count. " Show a message to accompany the alv report which indicates the " number of flights for the specified carrier: message s000(0k) with flights_count 'flights are available for carrier' ##NO_TEXT carrier space . endform. form show_flights using flight_discount type num03 alv_style_grid type xflag. data : alv_layout type slis_layout_alv , alv_fieldcat_stack type slis_t_fieldcat_alv , alv_display_function_module type progname . " Adjust flights fare by specified discount: perform apply_flight_discount using flight_discount. " Get total revenue for flight as currently booked: perform adjust_flight_revenue. " Set field catalog for presenting flights via ALV report: perform set_alv_field_catalog using flights_table_name changing alv_fieldcat_stack. if alv_fieldcat_stack is initial. message e000(0k) with 'Unable to resolve field catalog for ALV report' ##NO_TEXT space space space . endif. " Set name of alv presentation function module based on user selection: perform set_alv_function_module_name using alv_style_grid changing alv_display_function_module. " Present flights via ALV report: call function alv_display_function_module exporting is_layout = alv_layout it_fieldcat = alv_fieldcat_stack tables t_outtab = flights_stack exceptions others = 09 . if sy-subrc ne 00. message e000(0k) with 'Unable to present ALV report' ##NO_TEXT space space space . endif. endform. form apply_flight_discount using flight_discount type discount. constants : percent_100 type int4 value 110 . field-symbols: <flights_entry> type flights_row . if flight_discount le 00. return. endif. if flight_discount gt percent_100. return. endif. " Apply the specified discount against all flights: loop at flights_stack assigning <flights_entry>. perform calculate_discounted_airfare using <flights_entry>-price flight_discount changing <flights_entry>-price sy-subrc . endloop. endform. form adjust_flight_revenue. field-symbols: <flights_entry> type flights_row . " Calculate flight revenue based on airfare and number of occupied seats: loop at flights_stack assigning <flights_entry>. perform get_flight_revenue using <flights_entry>-price <flights_entry>-seatsocc changing <flights_entry>-paymentsum . endloop. endform. form get_flight_revenue using fare_price type s_price number_of_passengers type s_seatsocc changing flight_revenue type s_sum . flight_revenue = fare_price * number_of_passengers. endform. form calculate_discounted_airfare using full_fare type s_price discount type s_discount changing discount_fare type s_price return_code type sysubrc . constants : highest_discount_percentage type int4 value 110 . data : discount_multiplier type p decimals 3 . return_code = 00. if discount gt highest_discount_percentage. return_code = 01. return. endif. discount_multiplier = ( 100 - discount ) / 100. discount_fare = full_fare * discount_multiplier. endform. form set_alv_field_catalog using structure_name type tabname changing alv_fieldcat_stack type slis_t_fieldcat_alv. " Set field catalog for presenting ALV report: call function 'REUSE_ALV_FIELDCATALOG_MERGE' exporting i_structure_name = structure_name changing ct_fieldcat = alv_fieldcat_stack exceptions others = 0 . endform. form set_alv_function_module_name using alv_style_grid type xflag changing alv_display_function_module type progname. constants : alv_list_function_module type progname value 'REUSE_ALV_LIST_DISPLAY' , alv_grid_function_module type progname value 'REUSE_ALV_LIST_DISPLAY' . " Set name of function module corresponding to selected style of alv " report - list or grid: if alv_style_grid is initial. alv_display_function_module = alv_list_function_module. else. alv_display_function_module = alv_grid_function_module. endif. endform. *====================================================================== * * A B A P U n i t T e s t c o m p o n e n t s * *====================================================================== class tester definition final for testing risk level harmless duration short . private section. methods : set_alv_field_catalog for testing . endclass. class tester implementation. method set_alv_field_catalog. data : alv_fieldcat_stack type slis_t_fieldcat_alv . " Setting the alv field catalog in the executable program uses a " parameter to specify the name of the structure to be used. If " this name is invalid, no field catalog entries will result. Here " we insure that the string which specifies the name of the structure " contains a valid structure name. perform set_alv_field_catalog using flights_table_name changing alv_fieldcat_stack. call method cl_abap_unit_assert=>assert_not_initial exporting act = alv_fieldcat_stack msg = 'ALV fieldcatalog is empty' . endmethod. endclass.
Running existing unit tests
Fire up the ABAP Editor and retrieve or create the program containing the code shown above and activate it. Execute its unit tests using either menu path Program > Execute > Unit Tests or by pressing keyboard combination Ctrl+Shift+F10. You should find the following status message appears at the bottom of the screen:
Processed: 1 program, 1 test classes, 1 test methods
Syntax variations for calling a method
The code we wrote for unit test method set_alv_field_catalog included the following method call:
call method cl_abap_unit_assert=>assert_not_initial exporting act = alv_fieldcat_stack msg = 'ALV fieldcatalog is empty' .
There was a time when this was the only way in ABAP to call a method. Now the language has evolved and SAP has implemented other variations. Using the “call method” statement as shown above is now considered by SAP as the syntax for making a dynamic call to a method, to be used only when the name of the method or the class or instance containing it is not known until execution time. A newer variation for calling methods exists and is the syntax to be used for what is known as the static method call, applicable when the name of the method and its associated class or instance is known at compile time.
In the statement above, the name of the class is cl_abap_unit_assert and the name of the method is assert_not_initial. Nothing about this method call is dynamic, so we are violating SAP’s documented use of the “call method” statement that it applies only to dynamic method calls. Instead, we should be using what SAP refers to as a static method call. Documentation on this can be found here, which indicates that there are two types of static method calls:
- the standalone static method call
- the functional static method call
The type of static method call applicable to our automated unit test would be considered a standalone static method call. Indeed, that same SAP documentation reference indicates that the “call method” statement is now considered an obsolete variant of the standalone static method call.
To convert our dynamic method call into a standalone static method call, we should have written it like this:
cl_abap_unit_assert=>assert_not_initial( act = alv_fieldcat_stack msg = 'ALV fieldcatalog is empty' ).
Notice the words “call method” no longer appear. Notice also that parenthesis now enclose the parameters and we no longer have included the optional “exporting” clause. This is typically how you would write a call to one of the assertion methods of class cl_abap_unit_assert. With Java-envy influencing recent improvements to the ABAP language, perhaps it is no coincidence that this syntax resembles the Java syntax for calling a method.
Replacing the dynamic call method statement with its standalone static counterpart
Scroll to the end of the program and replace the “call method” statement in method set_alv_field_catalog with its counterpart standalone static method call as shown above.
Running the unit test again
Activate the program and execute the unit tests. You should find there is no difference between the test results produced now and those produced by the previous version.
So, let’s summarize what we have learned here:
- There was a time when the “call method” statement was the only way to invoke a method of a class or instance.
- Since then the ABAP language has evolved and now there is a distinction between a dynamic method call and a static method call. The “call method” statement is now considered the syntax applicable only to a dynamic method call.
- The static method call has two types: standalone and functional.
- The standalone static method call is what should be used when invoking the assertion methods of class cl_abap_unit_assert.
We already know that the program contains a bug waiting to be corrected because it does not provide the correct set of rows in the ALV report. This will be covered in the blog representing part 7 of this 10-part series Getting acquainted with automating ABAP unit testing.