Merge pull request #423 from backus/enhancement/zero-arity-arg-splat-mutation

Add mutation `def foo(*args); end` into `def foo(*args); args = []; end`

Changelog.md

@@ -2,6 +2,7 @@
 
 * Add mutation from `a != b` to `!a.eql?(b)` and `!a.equal?(b)` #417
 * Add mutation `A.const_get(:B)` -> `A::B` #426
+* Add mutation `def foo(*args); end` into `def foo(*args); args = []; end` #423
 
 # v0.8.3 2015-09-01
 

config/flay.yml

@@ -1,3 +1,3 @@
 ---
 threshold: 18
-total_score: 1214
+total_score: 1219

lib/mutant.rb

@@ -52,6 +52,7 @@ require 'mutant/ast/meta/send'
 require 'mutant/ast/meta/symbol'
 require 'mutant/ast/meta/optarg'
 require 'mutant/ast/meta/resbody'
+require 'mutant/ast/meta/restarg'
 require 'mutant/actor'
 require 'mutant/actor/receiver'
 require 'mutant/actor/sender'

lib/mutant/ast/meta/restarg.rb

@@ -0,0 +1,15 @@
+module Mutant
+  module AST
+    # Node meta information mixin
+    module Meta
+
+      # Metadata for restarg nodes
+      class Restarg
+        include NamedChildren, Concord.new(:node)
+
+        children :name
+      end # Restarg
+
+    end # Meta
+  end # AST
+end # Mutant

lib/mutant/mutator/node/define.rb

@@ -14,6 +14,7 @@ module Mutant
         def dispatch
           emit_arguments_mutations
           emit_optarg_body_assignments
+          emit_restarg_body_mutation
           emit_body(N_RAISE)
           emit_body(nil)
           emit_body_mutations if body
@@ -32,6 +33,19 @@ module Mutant
           end
         end
 
+        # Emit mutation with arg splat as empty array signment in method
+        #
+        # @return [undefined]
+        #
+        # @api private
+        def emit_restarg_body_mutation
+          arguments.children.each do |argument|
+            next unless n_restarg?(argument) && argument.children.one?
+
+            emit_body_prepend(s(:lvasgn, AST::Meta::Restarg.new(argument).name, s(:array)))
+          end
+        end
+
         # Emit valid body ASTs depending on instance body
         #
         # @param node [Parser::AST::Node]

meta/def.rb

@@ -5,6 +5,31 @@ Mutant::Meta::Example.add do
   mutation 'remove_method :foo'
 end
 
+Mutant::Meta::Example.add do
+  source 'def foo(a, *b); nil; end'
+
+  mutation 'def foo(_a, *b); nil; end'
+  mutation 'def foo; nil; end'
+  mutation 'def foo(a, *b); end'
+  mutation 'def foo(a, *b); raise; end'
+  mutation 'def foo(a); nil; end'
+  mutation 'def foo(*b); nil; end'
+  mutation 'def foo(a, *b); b = []; nil; end'
+  mutation 'remove_method :foo'
+end
+
+Mutant::Meta::Example.add do
+  source 'def foo(a, *); nil; end'
+
+  mutation 'def foo(_a, *); nil; end'
+  mutation 'def foo; nil; end'
+  mutation 'def foo(a, *); end'
+  mutation 'def foo(a, *); raise; end'
+  mutation 'def foo(a); nil; end'
+  mutation 'def foo(*); nil; end'
+  mutation 'remove_method :foo'
+end
+
 Mutant::Meta::Example.add do
   source 'def foo; foo; rescue; end'