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  1. Rules Repository
  2. RSPEC-1862 Related "if/else if" statements should not have the same condition
  3. RSPEC-4765

Ruby: Related "if/elsif" statements and "when" in a "case" should not have the same condition

    Details

    • Type: Language-Specification
    • Status: Active
    • Resolution: Unresolved
    • Labels:
      None
    • Impact:
      Unknown 'null' severity
    • Likelihood:
      Unknown 'null' severity

      Description

      A case and a chain of if/elsif statements is evaluated from top to bottom. At most, only one branch will be executed: the first one with a condition that evaluates to true.

      Therefore, duplicating a condition automatically leads to dead code. Usually, this is due to a copy/paste error. At best, it's simply dead code and at worst, it's a bug that is likely to induce further bugs as the code is maintained, and obviously it could lead to unexpected behavior.

      For a case, the second when will never be executed, rendering it dead code. Worse there is the risk in this situation that future maintenance will be done on the dead case, rather than on the one that's actually used.

      Noncompliant Code Example

      if param == 1
        openWindow()
      elsif param == 2
        closeWindow()
      elsif param == 1  # Noncompliant
        moveWindowToTheBackground()
      end
      
      case i
        when 1
          # ...
        when 3
          # ...
        when 1  # Noncompliant
          # ...
        else
          # ...
      end
      

      Compliant Solution

      if param == 1
        openWindow()
      elsif param == 2
        closeWindow()
      elsif param == 3
        moveWindowToTheBackground()
      end
      
      case i
        when 1
          # ...
        when 3
          # ...
        else
          # ...
      end
      

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            • Assignee:
              Unassigned
              Reporter:
              elena.vilchik Elena Vilchik
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              Dates

              • Created:
                Updated: