Merge pull request #1163 from AayushSabharwal/as/null-integrator-interface

feat: implement some of the integrator interface for `NullODEIntegrator`

Author: ChrisRackauckas

src/solve.jl

@@ -710,6 +710,8 @@ function step!(integ::NullODEIntegrator, dt = nothing, stop_at_tdt = false)
     end
     return nothing
 end
+function SciMLBase.u_modified!(integ::NullODEIntegrator, u) end
+SciMLBase.check_error(integ::NullODEIntegrator) = integ.sol.retcode
 
 function hack_null_solution_init(prob)
     if SciMLBase.has_initialization_data(prob.f)

test/downstream/null_de.jl

@@ -88,3 +88,10 @@ end
     sol = solve(prob)
     @test sol.resid isa SVector{1, Float64}
 end
+
+@testset "`u_modified!` works on null integrators" begin
+    prob = ODEProblem(Returns(nothing), nothing, (0.0, 1.0))
+    integ = init(prob, Tsit5())
+    @test_nowarn SciMLBase.u_modified!(integ, Float64[])
+    @test SciMLBase.successful_retcode(SciMLBase.check_error(integ))
+end