rspec/rules/S1871/abap/rule.adoc

Having two ``WHEN`` in a ``CASE`` statement or two branches in an ``IF`` chain  with the same implementation is at best duplicate code, and at worst a coding error. If the same logic is truly needed for both cases, they should be combined. 

== Noncompliant Code Example

----
CASE i.
  WHEN 1.
    doFirst.
    doSomething.
  WHEN 2.
    doSomethingDifferent.
  WHEN 3.  // Noncompliant; duplicates case 1's implementation
    doFirst.
    doSomething. 
  WHEN OTHERS. 
    doTheRest.
ENDCASE.

IF a >= 0 AND a < 10.
  doFirst.
  doTheThing.
ELSEIF a >= 10 AND a < 20.
  doTheOtherThing.
ELSEIF a >= 20 AND a < 50.
  doFirst.       // Noncompliant; duplicates first condition
  doTheThing.
ENDIF.
----

== Exceptions

Blocks in an ``IF`` chain or in ``CASE`` statement that contain a single line of code are ignored.

----
IF a >= 0 AND a < 10.
  doTheThing.
ELSEIF a >= 10 AND a < 20.
  doTheOtherThing.
ELSEIF a >= 20 AND a < 50.
  doTheThing.  // no issue, usually this is done on purpose to increase the readability
ENDIF.
----

But this exception does not apply to ``IF`` chains without final ``ELSE``-s, or to ``CASE``-s without ``WHEN OTHERS`` clauses when all branches have the same single line of code. In case of ``IF`` chains with ``ELSE``-s, or of ``CASE``-s with ``WHEN OTHERS`` clauses, rule S3923 raises a bug. 

----
if a >= 0 AND a < 10. //Noncompliant, this might have been done on purpose but probably not
  doTheThing.
elseif a >= 10 AND a < 20.
  doTheThing.
endif.
----