test: test scalarized array passed to discrete_parameters of symbolic affect

Author: AayushSabharwal

test/symbolic_events.jl

@@ -1455,3 +1455,19 @@ end
                                                                                Pre(X) +
                                                                                10.0])
 end
+
+@testset "Issue#3990: Scalarized array passed to `discrete_parameters` of symbolic affect" begin
+    @parameters p(t)[1:2] d
+    @variables X(t) Y(t)
+    eqs = [
+        D(X) ~ p[1] - d*X,
+        D(Y) ~ p[2] - d*Y
+    ]
+    devent = SymbolicDiscreteCallback([1.0] => [p[1] ~ 0.0, p[2] ~ 0.0]; discrete_parameters = collect(p))
+    @mtkcompile sys = System(eqs, t; discrete_events = devent)
+
+    sim_cond = [X => 1.0, Y => 2.0, p => [1.0, 2.0], d => 1.0]
+    oprob = ODEProblem(sys, sim_cond, 2.0)
+    sol = solve(oprob)
+    @test sol[p] ≈ [[1.0, 2.0], [0.0, 0.0]]
+end