Assert library

Following official documentation we're supposed to write unit tests using following template

cl_abap_unit_assert=>assert_equals( act = myclass=>text
                                    exp = 'X' ).

The only function this library delivers - it allows us to use shorter construction like this:

assert( myclass=>text )->equals( 'X' ).

Usage in unit tests

To use this library you need to use ZCL_ASSERTABLE_UNIT class as a base class for your test class.

CLASS ltcl_main DEFINITION INHERITING FROM zcl_assertable_unit
    FINAL FOR TESTING
  DURATION SHORT
  RISK LEVEL HARMLESS.
...
endclass.

then later in your code you can just use something like:

    assert( 1 )->not_initial( ).
    assert( 1 )->eq( 1 ).
    assert( 1 )->ne( 2 ).
    assert( new ltcl_main( ) )->bound( ).
    assert( not_bound )->not_bound( ).
    assert( abap_true )->true( ).
    assert( abap_false )->false( ).

Local asserts

It might be helpful to use assert interface in a normal runtime, not only in unit tests.

data(assert) = new zcl_assertable( ).
assert->assert( 1 )->not_initial( ).

or if your class is inherited from ZCL_ASSERTABLE then simply like this

assert( 1 )->not_initial( ).

alternatively you can implement zif_assert interface right in your class:

class zcl_your_class definition.
  public section.
    interfaces zif_assertable.
  private section.
    aliases assert for zif_assertable~assert.
    methods some_method.
endclass.
class zcl_your_class implementation.
  method zif_assertable~assert.
    result = new zcl_assertable( actual = actual ).
  endmethod.
  method some_method.
    assert( some_value )->eq( another_value ).
  endmethod.
endclass.

PLease notice in this case if zcl_assert_local interface will be extended ( with methods/parameters ) you will have to support this change too in your class.

Exception handling in local mode

One more feature which local asserts bring is a resumable exception. For example you can assert and catch assertion exception (which native asserts do not support BTW).

try.
  assert( ref )->is_bound( ).
catch zcx_assertable.
  " some exception handling
endtry.

Since ZCX_ASSERTABLE is a no-check exception you can bring it higher and do even more advanced logic

method main.
  try.
    do_something( ref ).
  catch before unwind zcx_assertable.
    " fix the problem here
    ref = new #( ).
    resume.
  endtry.
endmethod.

method do_something.
  assert( ref )->is_bound( ).
endmethod.