require "./spec_helper"

describe Graph do
  describe "#find_path" do
    it "reports no paths in a graph with no edges" do
      gr = Graph(String).new
      elems = ["a", "b", "c", "d"]
      elems.each &->gr.add_node(String)
      elems.each do |elem|
        elems.each do |other|
          next if elem == other
          gr.find_path(elem, other).should be_nil
        end
      end
    end

    it "computes the shortest path" do
      gr = Graph(String).new
      [{"a", "b", 1}, {"a", "c", 1}, {"c", "b", 1}, {"b", "d", 1}].each do |t|
        from, to, cost = t
        gr.add_edge(from, to, cost)
      end
      gr.find_path("a", "d").should eq({["a", "b", "d"], 2})
    end
  end
end