add test

test/runtests.jl

@@ -56,6 +56,11 @@ end
  include("test_PlanarMechanics.jl")
 end
 
+@testset "urdf" begin
+ @info "Testing urdf"
+ include("test_urdf.jl")
+end
+
 
 # ==============================================================================
 ## Add spring to make a harmonic oscillator ====================================

test/test_urdf.jl

@@ -0,0 +1,22 @@
+using Test
+using ModelingToolkit, Multibody, LightXML, Graphs, MetaGraphsNext, JuliaFormatter
+cd(@__DIR__)
+# URDF = Base.get_extension(Multibody, :URDF)
+
+urdf2multibody(joinpath(dirname(pathof(Multibody)), "..", "test", "urdf", "doublependulum.urdf"), extras=false, out="doublependulum.jl", modelname="DoublePendulum")
+
+include("doublependulum.jl")
+
+
+
+using ModelingToolkit, Multibody, JuliaSimCompiler, OrdinaryDiffEq#, Plots
+import ModelingToolkit: t_nounits as t, D_nounits as D
+W(args...; kwargs...) = Multibody.world
+@named model = DoublePendulum()
+model = complete(model)
+ssys = structural_simplify(IRSystem(model))
+prob = ODEProblem(ssys, [], (0.0, 10.0))
+sol = solve(prob, Tsit5())
+@test SciMLBase.successful_retcode(sol)
+@test !iszero(sol.u[end])
+# plot(sol) |> display