Class: Mutineer::Mutators::Comparison

Inherits:
Base
  • Object
show all
Defined in:
lib/mutineer/mutators/comparison.rb

Overview

Comparison / boundary operator: <->-<=, >->-=>, ==->!=, etc. The single highest-value Tier-1 family (spec §4) — exposes off-by-one and boundary gaps line coverage never catches. Rewrites the operator token (CallNode#message_loc), one mutation per occurrence.

Clean-room: implemented from the spec's operator table and public mutation-testing literature, not the mutant gem.

Constant Summary collapse

REPLACEMENTS = 
{
  :< => "<=", :<= => "<", :> => ">=", :>= => ">", :== => "!=", :!= => "=="
}.freeze

Instance Method Summary collapse

Methods inherited from Base

#mutations_for

Instance Method Details

#visit_call_node(node) ⇒ Object 



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# File 'lib/mutineer/mutators/comparison.rb', line 19

def visit_call_node(node)
  replacement = REPLACEMENTS[node.name]
  loc = node.message_loc
  # receiver guard: reject any unary call accidentally named like an
  # operator; binary comparisons always have a receiver.
  if replacement && loc && node.receiver
    @mutations << Mutation.new(
      start_offset: loc.start_offset,
      end_offset: loc.end_offset,
      replacement: replacement,
      operator: :comparison
    )
  end
  super # nested comparisons (a >= b && c <= d) each get their own mutation
end