From df7de1ee86c2c69cf80379b747e890612d27abfa Mon Sep 17 00:00:00 2001
From: Markus Schirp <mbj@schirp-dso.com>
Date: Fri, 28 Mar 2014 15:42:46 +0000
Subject: [PATCH] Delete memoizer on Subject#prepare

---
 lib/mutant/subject/method/instance.rb         | 12 ++++++++
 .../mutant/subject/method/instance_spec.rb    | 29 +++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/lib/mutant/subject/method/instance.rb b/lib/mutant/subject/method/instance.rb
index c741b5df..cceb4124 100644
--- a/lib/mutant/subject/method/instance.rb
+++ b/lib/mutant/subject/method/instance.rb
@@ -52,6 +52,18 @@ module Mutant
           end
           memoize :source
 
+          # Prepare subject for mutation insertion
+          #
+          # @return [self]
+          #
+          # @api private
+          #
+          def prepare
+            scope.send(:memoized_methods).instance_variable_get(:@memory).delete(name)
+            scope.send(:undef_method, name)
+            self
+          end
+
         private
 
           # Return mutations
diff --git a/spec/unit/mutant/subject/method/instance_spec.rb b/spec/unit/mutant/subject/method/instance_spec.rb
index 02d71ec0..76b29207 100644
--- a/spec/unit/mutant/subject/method/instance_spec.rb
+++ b/spec/unit/mutant/subject/method/instance_spec.rb
@@ -51,6 +51,35 @@ describe Mutant::Subject::Method::Instance::Memoized do
     s(:def, :foo, s(:args))
   end
 
+  describe '#prepare' do
+
+    let(:context) do
+      Mutant::Context::Scope.new(scope, double('Source Path'))
+    end
+
+    let(:scope) do
+      Class.new do
+        include Memoizable
+        def foo
+        end
+        memoize :foo
+      end
+    end
+
+    subject { object.prepare }
+
+    it 'undefines memoizer' do
+      expect { subject }.to change { scope.memoized?(:foo) }.from(true).to(false)
+    end
+
+    it 'undefines method on scope' do
+      expect { subject }.to change { scope.instance_methods.include?(:foo) }.from(true).to(false)
+    end
+
+    it_should_behave_like 'a command method'
+  end
+
+
   describe '#source' do
     subject { object.source }