From eae33f92dbeb255dcd4c8bc3e748c7d43b2fd8e9 Mon Sep 17 00:00:00 2001
From: D4L <Austin.L.D4L@gmail.com>
Date: Wed, 2 Jan 2013 14:08:16 -0500
Subject: [PATCH] Make graph dup do a deep copy. Closes #6

---
 lib/abstract_graph/graph.rb           |  1 +
 lib/abstract_graph/graph/dup.rb       | 14 ++++++++++
 spec/abstract_graph/graph/dup_spec.rb | 37 +++++++++++++++++++++++++++
 3 files changed, 52 insertions(+)
 create mode 100644 lib/abstract_graph/graph/dup.rb
 create mode 100644 spec/abstract_graph/graph/dup_spec.rb

diff --git a/lib/abstract_graph/graph.rb b/lib/abstract_graph/graph.rb
index 1b6889e..4e66a92 100644
--- a/lib/abstract_graph/graph.rb
+++ b/lib/abstract_graph/graph.rb
@@ -17,3 +17,4 @@ class Graph
 require "abstract_graph/graph/initialize"
 require "abstract_graph/graph/add_vertex"
 require "abstract_graph/graph/has_vertex"
+require "abstract_graph/graph/dup"
diff --git a/lib/abstract_graph/graph/dup.rb b/lib/abstract_graph/graph/dup.rb
new file mode 100644
index 0000000..2fbc77c
--- /dev/null
+++ b/lib/abstract_graph/graph/dup.rb
@@ -0,0 +1,14 @@
+# required in "abstract_graph/graph"
+
+module AbstractGraph
+  class Graph
+
+    # does a deep copy of the graph
+    def dup
+      other = Graph.new
+      other.vertices = @vertices.dup
+      other
+    end
+
+  end
+end
diff --git a/spec/abstract_graph/graph/dup_spec.rb b/spec/abstract_graph/graph/dup_spec.rb
new file mode 100644
index 0000000..43f45e9
--- /dev/null
+++ b/spec/abstract_graph/graph/dup_spec.rb
@@ -0,0 +1,37 @@
+require 'spec_helper'
+
+module AbstractGraph
+  module Composition
+    describe Graph do
+
+      before :each do
+        @graph = Graph.new
+        @graph.add_vertex "MyVertex"
+      end
+
+      describe "#dup" do
+
+        it "returns a graph object" do
+          @graph.dup.should be_an_instance_of(Graph)
+        end
+
+        it "has a different id than the original graph" do
+          @graph.object_id.should_not == @graph.dup.object_id
+        end
+
+        it "copies over the existing vertices" do
+          graphdup = @graph.dup
+          graphdup.has_vertex?( "MyVertex" ).should be_true
+        end
+
+        it "will not modify the original if it is modified" do
+          graphdup = @graph.dup
+          graphdup.vertices.clear
+          @graph.vertices.size.should == 1
+        end
+
+      end
+
+    end
+  end
+end