move test

Author: aml5600

test/input_output_handling.jl

@@ -171,16 +171,6 @@ x = [rand()]
 u = [rand()]
 @test f[1](x, u, p, 1) == -x + u
 
-@testset "Constants substitution" begin
-    @constants c = 2.0
-    @variables x(t)
-    eqs = [D(x) ~ c * x]
-    @named sys = ODESystem(eqs, t, [x], [])
-
-    f, dvs, ps = ModelingToolkit.generate_control_function(sys, simplify = true)
-    @test f[1]([0.5], nothing, nothing, 0.0) == [1.0]
-end
-
 # more complicated system
 
 @variables u(t) [input = true]
@@ -401,3 +391,14 @@ matrices, ssys = linearize(augmented_sys,
         io_sys, [x + u * t]; inputs = [u])
     @test obsfn([1.0], [2.0], nothing, 3.0) == [7.0]
 end
+
+# https://github.com/SciML/ModelingToolkit.jl/issues/2896
+@testset "Constants substitution" begin
+    @constants c = 2.0
+    @variables x(t)
+    eqs = [D(x) ~ c * x]
+    @named sys = ODESystem(eqs, t, [x], [])
+
+    f, dvs, ps = ModelingToolkit.generate_control_function(sys, simplify = true)
+    @test f[1]([0.5], nothing, nothing, 0.0) == [1.0]
+end