Add unary call mutation

Changelog.md

@@ -1,6 +1,7 @@
 # v0.2.8 2012-12-29
 
-* [feature] Mutate method call receivers "foo.bar" => "foo"
+* [feature] Mutate unary calls ```coerce(object)``` => ```object```
+* [feature] Mutate method call receivers ```foo.bar``` => ```foo```
 
 [Compare v0.2.7..v0.2.8](https://github.com/mbj/mutant/compare/v0.2.7...v0.2.8)
 
@@ -22,7 +23,7 @@
 * [feature] Run noop mutation per subject to guard against initial failing specs
 * [feature] Mutate default into required arguments
 * [feature] Mutate default literals
-* [feature] Mutate unwinding of pattern args |(a, b), c] => |a, b, c|
+* [feature] Mutate unwinding of pattern args ```|(a, b), c|``` => ```|a, b, c|```
 * [feature] Mutate define and block arguments
 * [feature] Mutate block arguments, inklusive pattern args
 * [feature] Recurse into block bodies

lib/mutant/mutator/node/send.rb

@@ -152,9 +152,22 @@ module Mutant
           #
           def dispatch
             super
+            emit_call_remove_mutation
             emit_attribute_mutations(:arguments)
           end
 
+          # Emit transfomr call mutation
+          #
+          # @return [undefined]
+          #
+          # @api private
+          #
+          def emit_call_remove_mutation
+            array = node.arguments.array
+            return unless array.length == 1
+            emit(array.first)
+          end
+
         end
       end
     end

spec/unit/mutant/mutator/node/send/mutation_spec.rb

@@ -42,6 +42,7 @@ describe Mutant::Mutator, 'send' do
       let(:mutations) do 
         mutations = []
         mutations << 'foo()'
+        mutations << 'nil'
         mutations << 'foo(Object.new)'
       end