add spec for bellman ford

Author: brianstorti

bellman_ford/spec.rb

@@ -0,0 +1,31 @@
+require'minitest/autorun'
+
+require_relative'graph'
+require_relative'node'
+require_relative'edge'
+require_relative'bellman_ford'
+
+describeBellmanForddo
+beforedo
+@graph=Graph.new
+
+@graph.add_node(@node0=Node.new("Node #0"))
+@graph.add_node(@node1=Node.new("Node #1"))
+@graph.add_node(@node2=Node.new("Node #2"))
+@graph.add_node(@node3=Node.new("Node #3"))
+@graph.add_node(@node4=Node.new("Node #4"))
+end
+
+it'finds the shortest path with negative weights'do
+@graph.add_edge(@node0,@node1,1)
+@graph.add_edge(@node0,@node4,2)
+@graph.add_edge(@node1,@node2,4)
+@graph.add_edge(@node2,@node4,1)
+@graph.add_edge(@node2,@node3,20)
+@graph.add_edge(@node3,@node4, -25)
+
+shortest_path=BellmanFord.new(@graph,@node0).shortest_path_to(@node4)
+
+shortest_path.must_equal[@node0,@node1,@node2,@node3,@node4]
+end
+end