Add more Jacobian tests

Author: YingboMa

test/odesystem.jl

@@ -1,4 +1,5 @@
 using ModelingToolkit, StaticArrays, LinearAlgebra
+using OrdinaryDiffEq
 using DiffEqBase
 using Test
 
@@ -209,6 +210,11 @@ p  = [k₁ => 0.04,
       k₂ => 3e7,
       k₃ => 1e4]
 tspan = (0.0,100000.0)
-prob = ODEProblem(sys,u0,tspan,p)
-sol = solve(prob, Rodas5())
-@test all(x->sum(x) ≈ 1.0, sol.u)
+prob1 = ODEProblem(sys,u0,tspan,p)
+prob2 = ODEProblem(sys,u0,tspan,p,jac=true)
+# Wfact version is not very stable because of the lack of pivoting
+prob3 = ODEProblem(sys,u0,tspan,p,Wfact=true,Wfact_t=true)
+for (prob, atol) in [(prob1, 1e-12), (prob2, 1e-12), (prob3, 0.1)]
+    sol = solve(prob, Rodas5())
+    @test all(x->≈(sum(x), 1.0, atol=atol), sol.u)
+end