forgot a file

Author: ChrisRackauckas

test/downstream/symbol_indexing.jl

@@ -1,10 +1,8 @@
 using ModelingToolkit, OrdinaryDiffEq, RecursiveArrayTools, SymbolicIndexingInterface, Test
 using Optimization, OptimizationOptimJL
-# compat for MTKv8 and v9
-unknowns = isdefined(ModelingToolkit, :states) ? ModelingToolkit.states :
-           ModelingToolkit.unknowns
+using ModelingToolkit: t_nounits as t, D_nounits as D
 
-@parameters t σ ρ β
+@parameters σ ρ β
 @variables x(t) y(t) z(t)
 D = Differential(t)
 
@@ -19,8 +17,7 @@ eqs = [D(x) ~ σ * (y - x),
 @variables a(t) α(t)
 connections = [0 ~ lorenz1.x + lorenz2.y + a * γ,
     α ~ 2lorenz1.x + a * γ]
-@named sys = ODESystem(connections, t, [a, α], [γ], systems = [lorenz1, lorenz2])
-sys_simplified = structural_simplify(sys)
+@mtkbuild sys = ODESystem(connections, t, [a, α], [γ], systems = [lorenz1, lorenz2])
 
 u0 = [lorenz1.x => 1.0,
     lorenz1.y => 0.0,
@@ -39,7 +36,7 @@ p = [lorenz1.σ => 10.0,
     γ => 2.0]
 
 tspan = (0.0, 100.0)
-prob = ODEProblem(sys_simplified, u0, tspan, p)
+prob = ODEProblem(sys, u0, tspan, p)
 integ = init(prob, Rodas4())
 sol = solve(prob, Rodas4())
 
@@ -135,7 +132,7 @@ sol1 = sol(0.0:1.0:10.0)
 
 sol2 = sol(0.1)
 @test sol2 isa Vector
-@test length(sol2) == length(unknowns(sys_simplified))
+@test length(sol2) == length(unknowns(sys))
 @test first(sol2) isa Real
 
 sol3 = sol(0.0:1.0:10.0, idxs = [lorenz1.x, lorenz2.x])
@@ -191,9 +188,9 @@ sol10 = sol(0.1, idxs = 2)
 @test sol10 isa Real
 
 @test is_timeseries(sol) == Timeseries()
-getx = getu(sys_simplified, lorenz1.x)
-get_arr = getu(sys_simplified, [lorenz1.x, lorenz2.x])
-get_tuple = getu(sys_simplified, (lorenz1.x, lorenz2.x))
+getx = getu(sys, lorenz1.x)
+get_arr = getu(sys, [lorenz1.x, lorenz2.x])
+get_tuple = getu(sys, (lorenz1.x, lorenz2.x))
 get_obs = getu(sol, lorenz1.x + lorenz2.x) # can't use sys for observed
 get_obs_arr = getu(sol, [lorenz1.x + lorenz2.x, lorenz1.y + lorenz2.y])
 l1x_idx = variable_index(sol, lorenz1.x)