test: ensure tunable_parameters are now correctly ordered

Author: AayushSabharwal

src/variables.jl

@@ -381,7 +381,12 @@ Create a tunable parameter by
 @parameters u [tunable=true]
 ```
 
-See also [`getbounds`](@ref), [`istunable`](@ref)
+For systems created with `split = true` (the default) and `default = true` passed to this function, the order
+of parameters returned is the order in which they are stored in the tunables portion of `MTKParameters`. Note
+that array variables will not be scalarized. To obtain the flattened representation of the tunables portion,
+call `Symbolics.scalarize(tunable_parameters(sys))` and concatenate the resulting arrays.
+
+See also [`getbounds`](@ref), [`istunable`](@ref), [`MTKParameters`](@ref), [`complete`](@ref)
 """
 function tunable_parameters(sys, p = parameters(sys); default = true)
     filter(x -> istunable(x, default), p)

test/index_cache.jl

@@ -1,4 +1,4 @@
-using ModelingToolkit, SymbolicIndexingInterface
+using ModelingToolkit, SymbolicIndexingInterface, SciMLStructures
 using ModelingToolkit: t_nounits as t
 
 # Ensure indexes of array symbolics are cached appropriately
@@ -43,3 +43,23 @@ ic = ModelingToolkit.get_index_cache(sys)
 @test isequal(ic.symbol_to_variable[:x], x)
 @test isequal(ic.symbol_to_variable[:y], y)
 @test isequal(ic.symbol_to_variable[:z], z)
+
+@testset "tunable_parameters is ordered" begin
+    @parameters p q[1:3] r[1:2, 1:2] s [tunable = false]
+    @named sys = ODESystem(Equation[], t, [], [p, q, r, s])
+    sys = complete(sys)
+    @test all(splat(isequal), zip(tunable_parameters(sys), parameters(sys)[1:3]))
+
+    offset = 1
+    for par in tunable_parameters(sys)
+        idx = parameter_index(sys, par)
+        @test idx.portion isa SciMLStructures.Tunable
+        if Symbolics.isarraysymbolic(par)
+            @test vec(idx.idx) == offset:(offset + length(par) - 1)
+        else
+            @test idx.idx == offset
+        end
+        offset += length(par)
+    end
+end
+

test/runtests.jl

@@ -24,7 +24,6 @@ end
             @safetestset "Parsing Test" include("variable_parsing.jl")
             @safetestset "Simplify Test" include("simplify.jl")
             @safetestset "Direct Usage Test" include("direct.jl")
-            @safetestset "IndexCache Test" include("index_cache.jl")
             @safetestset "System Linearity Test" include("linearity.jl")
             @safetestset "Input Output Test" include("input_output_handling.jl")
             @safetestset "Clock Test" include("clock.jl")
@@ -65,6 +64,7 @@ end
 
     if GROUP == "All" || GROUP == "InterfaceII"
         @testset "InterfaceII" begin
+            @safetestset "IndexCache Test" include("index_cache.jl")
             @safetestset "Variable Utils Test" include("variable_utils.jl")
             @safetestset "Variable Metadata Test" include("test_variable_metadata.jl")
             @safetestset "OptimizationSystem Test" include("optimizationsystem.jl")