TRSP by vertex test fails in some instances

[jordanderson]

In some instances (perhaps one in ten runs) this TRSP by vertex test condition fails:

@trsp_v.run :source => 12, :target => 13
expect(@trsp_v.path.all_nodes).to eq([12, 11, 10, 13])

Odd that it would be order-dependent since it's read-only, but who knows... Full output:

/Users/jordan/.rvm/rubies/ruby-1.9.3-p392/bin/ruby -S rspec ./spec/rb_routing_spec.rb
Creating database rb_routing_test for testing
psql:/Users/jordan/projects/rb_routing/spec/fixtures/test_database.sql:17: NOTICE:  CREATE TABLE will create implicit sequence "edge_table_id_seq" for serial column "edge_table.id"
psql:/Users/jordan/projects/rb_routing/spec/fixtures/test_database.sql:23: NOTICE:  CREATE TABLE will create implicit sequence "vertex_table_id_seq" for serial column "vertex_table.id"
Running osm2pgrouting -file ../examples/san-francisco.osm -dbname rb_routing_test -user postgres -conf ../examples/mapconfig.xml -passwd postgres
..F.......

Failures:

  1) RbRouting finds the shortest path with TRSP by vertex
     Failure/Error: expect(@trsp_v.path.all_nodes).to eq([12, 11, 10, 13])

       expected: [12, 11, 10, 13]
            got: [12, 9, 8, 7, 10, 13]

       (compared using ==)
     # ./spec/rb_routing_spec.rb:67:in `block (2 levels) in <top (required)>'

Finished in 0.27801 seconds
10 examples, 1 failure

Failed examples:

rspec ./spec/rb_routing_spec.rb:62 # RbRouting finds the shortest path with TRSP by vertex
/Users/jordan/.rvm/rubies/ruby-1.9.3-p392/bin/ruby -S rspec ./spec/rb_routing_spec.rb failed

[jordanderson]

The @trsp_v @Result that fails looks like

@result=[{:seq=>0, :node=>12, :edge=>15, :cost=>1.0e-323, :reverse_cost=>1.0e-323}, ...]

The @trsp_v @Result that succeeds looks like:

@result=[{:seq=>0, :node=>12, :edge=>13, :cost=>0.0, :reverse_cost=>0.0}, ...]

So I need to figure out where those tiny non-zero costs are coming from.