PNG of Dependency Graph

Gemfile

gem 'ruby-graphviz'

print.rb

print_graph("#{test_case.name} (expected)", test_case.result)
print_graph("#{test_case.name}", result)

resolver_spec.rb

def print_graph(name, dependency_graph)
  require 'graphviz'

  # Create a new graph
  g = GraphViz.new(:G, :type => :digraph)

  add_child = lambda do |graph, parent, child|
    cn = g.add_node("#{child.name} (#{child.payload.version})")
    g.add_edges(parent, cn)
    child.successors.each do |c|
      add_child.call(graph, cn, c)
    end
  end

  dependency_graph.root_vertices.values.each do |v|
    node = g.add_node("#{v.name} (#{v.payload.version})")
    v.successors.each do |s|
      add_child.call(g, node, s)
    end
  end

  # Generate output image
  g.output(:png => "#{name}.png")
end