Add mutations from /foo|bar/ -> /foo/ and /bar/

config/flay.yml

@@ -1,3 +1,3 @@
 ---
 threshold: 16
-total_score: 1317
+total_score: 1306

lib/mutant.rb

@@ -91,6 +91,7 @@ require 'mutant/mutator/util/symbol'
 require 'mutant/mutator/node'
 require 'mutant/mutator/node/generic'
 require 'mutant/mutator/node/regexp'
+require 'mutant/mutator/node/regexp/alternation_meta'
 require 'mutant/mutator/node/regexp/character_type'
 require 'mutant/mutator/node/literal'
 require 'mutant/mutator/node/literal/boolean'

lib/mutant/mutator/node/generic.rb

@@ -47,6 +47,7 @@ module Mutant
           regexp_nonspace_type
           regexp_word_boundary_anchor
           regexp_nonword_boundary_anchor
+          regexp_alternation_meta
         ]
 
         # These nodes still need a dedicated mutator,

lib/mutant/mutator/node/regexp/alternation_meta.rb

@@ -0,0 +1,21 @@
+module Mutant
+  class Mutator
+    class Node
+      module Regexp
+        # Mutator for pipe in `/foo|bar/` regexp
+        class AlternationMeta < Node
+          handle(:regexp_alternation_meta)
+
+        private
+
+          # Dispatch mutations
+          #
+          # @return [undefined]
+          def dispatch
+            children.each_index(&method(:delete_child))
+          end
+        end # AlternationMeta
+      end # Regexp
+    end # Node
+  end # Mutator
+end # Mutant

meta/regexp/regexp_alternation_meta.rb

@@ -3,4 +3,8 @@ Mutant::Meta::Example.add :regexp_alternation_meta do
 
   singleton_mutations
   regexp_mutations
+
+  mutation '/\A(foo|bar)\z/'
+  mutation '/\A(foo|baz)\z/'
+  mutation '/\A(bar|baz)\z/'
 end