Add integration test for serialization with Marshal

spec/integration/serializable_spec.rb

@@ -0,0 +1,19 @@
+# encoding: utf-8
+
+require 'spec_helper'
+
+class Serializable
+  include Memoizable
+  def method; end
+  memoize :method
+end
+
+describe 'A serializable object' do
+  let(:serializable) do
+    Serializable.new
+  end
+  it 'is serializable with Marshal' do
+    serializable.method # Call the method to trigger lazy memoization
+    expect { Marshal.dump(serializable) }.not_to raise_error
+  end
+end