Fix Ralston4 test imports, inference.jl typo and formatting

- Replace isdefined guards with direct imports of Ralston4
- Replace conditional splat with plain Ralston4() calls
- step_limiter_test.jl: remove redundant explicit import
- Fix inferrable -> inferable typo in inference.jl
- Runic formatted inference.jl

Author: Harsh Singh

test/integrators/step_limiter_test.jl

@@ -1,7 +1,6 @@
 using OrdinaryDiffEq, Test
 using OrdinaryDiffEqFIRK: AdaptiveRadau, RadauIIA9, RadauIIA5, RadauIIA3
 using OrdinaryDiffEqLowOrderRK
-const _has_Ralston4 = isdefined(OrdinaryDiffEqLowOrderRK, :Ralston4)
 
 # define the counting variable
 const STEP_LIMITER_VAR = Ref(0)
@@ -31,7 +30,7 @@ end
         Rosenbrock23, Rosenbrock32, ROS3P, Rodas3, Rodas23W, Rodas3P, Rodas4, Rodas42,
         Rodas4P, Rodas4P2, Rodas5, Rodas5P, Rodas5Pe, Rodas5Pr,
         AdaptiveRadau, RadauIIA9, RadauIIA5, RadauIIA3, SIR54,
-        Alshina2, Alshina3, Heun, Ralston, (_has_Ralston4 ? (OrdinaryDiffEqLowOrderRK.Ralston4,) : ())..., Midpoint, RK4,
+        Alshina2, Alshina3, Heun, Ralston, Ralston4, Midpoint, RK4,
         OwrenZen3, OwrenZen4, OwrenZen5,
         BS3, DP5, Tsit5, DP8, TanYam7, TsitPap8, FRK65, PFRK87, BS5, Vern6, Vern7,
         Vern8, Vern9, QPRK98, SSPRKMSVS43, SSPRKMSVS32, SSPRK432, SSPRK43,

test/interface/float32.jl

@@ -1,6 +1,5 @@
 using OrdinaryDiffEq, Test
-using OrdinaryDiffEqLowOrderRK
-const _has_Ralston4 = isdefined(OrdinaryDiffEqLowOrderRK, :Ralston4)
+using OrdinaryDiffEqLowOrderRK: Ralston4
 function some_arbitrary_function!(du, u, p, τ)
     du = u / 100
     return nothing #function returns nothing
@@ -13,7 +12,7 @@ tspan = (zero(NF), NF(1.0e3)) #integrate from t=0 to t = 1000
 ode_prob = ODEProblem(some_arbitrary_function!, u, tspan, params)
 
 for alg in [
-        Euler(), Midpoint(), Heun(), Ralston(), (_has_Ralston4 ? (OrdinaryDiffEqLowOrderRK.Ralston4(),) : ())..., RK4(), SSPRK104(), SSPRK22(), SSPRK33(),
+        Euler(), Midpoint(), Heun(), Ralston(), Ralston4(), RK4(), SSPRK104(), SSPRK22(), SSPRK33(),
         SSPRK43(), SSPRK432(), BS3(), BS5(), DP5(), DP8(), Feagin10(), Feagin12(),
         Feagin14(), TanYam7(), Tsit5(), TsitPap8(), Vern6(), Vern7(), Vern8(), Vern9(),
     ]

test/interface/units_tests.jl

@@ -1,11 +1,10 @@
 using OrdinaryDiffEq, RecursiveArrayTools, Unitful
-using OrdinaryDiffEqLowOrderRK
-const _has_Ralston4 = isdefined(OrdinaryDiffEqLowOrderRK, :Ralston4)
+using OrdinaryDiffEqLowOrderRK: Ralston4
 using LinearAlgebra, Test, ADTypes
 
 @testset "Algorithms" begin
     algs = [
-        Euler(), Midpoint(), Heun(), Ralston(), (_has_Ralston4 ? (OrdinaryDiffEqLowOrderRK.Ralston4(),) : ())..., RK4(), SSPRK104(), SSPRK22(), SSPRK33(),
+        Euler(), Midpoint(), Heun(), Ralston(), Ralston4(), RK4(), SSPRK104(), SSPRK22(), SSPRK33(),
         SSPRK43(), SSPRK432(), BS3(), BS5(), DP5(), DP8(), Feagin10(), Feagin12(),
         Feagin14(), TanYam7(), Tsit5(), TsitPap8(), Vern6(), Vern7(), Vern8(), Vern9(),
     ]