Additional testing of propagator interface

Author: goerz

test/test_prop_interfaces.jl

@@ -1,7 +1,7 @@
 using Test
 
 using QuantumControlTestUtils.RandomObjects: random_state_vector, random_dynamic_generator
-using QuantumPropagators: init_prop
+using QuantumPropagators: QuantumPropagators, init_prop
 using QuantumPropagators.Interfaces: check_propagator
 using StableRNGs: StableRNG
 using OrdinaryDiffEq: OrdinaryDiffEq
@@ -241,3 +241,123 @@ end
     @test check_propagator(propagator)
 
 end
+
+
+# Minimal struct for testing the base set_t! (all built-in propagators override it)
+mutable struct _SimpleProp
+    tlist::Vector{Float64}
+    t::Float64
+end
+
+# Minimal AbstractPropagator that ignores piecewise/pwc, for testing enforcement errors
+struct _NonPiecewiseProp <: QuantumPropagators.AbstractPropagator end
+
+function QuantumPropagators.init_prop(state, generator, tlist, ::Val{:_non_piecewise}; _...)
+    return _NonPiecewiseProp()
+end
+
+
+@testset "Propagator property access" begin
+
+    N = 10
+    tlist = collect(range(0, 10, length = 101))
+    rng = StableRNG(677918059)
+    Ψ = random_state_vector(N; rng)
+    Ĥ = random_dynamic_generator(N, tlist; rng)
+    propagator = init_prop(Ψ, Ĥ, tlist; method = :cheby)
+
+    @test_throws ErrorException propagator.generator
+    @test_throws ErrorException (propagator.state = Ψ)
+    @test_throws ErrorException (propagator.tlist = tlist)
+    @test_throws ErrorException (propagator.t = 0.0)
+    @test_throws ErrorException (propagator.generator = Ĥ)
+
+    new_params = copy(propagator.parameters)
+    propagator.parameters = new_params
+    @test propagator.parameters === new_params
+
+    pub = propertynames(propagator)
+    @test pub == (:state, :tlist, :t, :parameters, :backward, :inplace)
+
+    priv = propertynames(propagator, true)
+    @test length(priv) >= length(pub)
+    @test all(p ∈ priv for p ∈ pub)
+
+end
+
+
+@testset "init_prop piecewise enforcement" begin
+
+    N = 10
+    tlist = collect(range(0, 10, length = 101))
+    rng = StableRNG(677918060)
+    Ψ = random_state_vector(N; rng)
+    Ĥ = random_dynamic_generator(N, tlist; rng)
+
+    # piecewise=true with a PWC method works (ChebyPropagator isa PiecewisePropagator)
+    propagator = init_prop(Ψ, Ĥ, tlist; method = :cheby, piecewise = true)
+    @test propagator isa QuantumPropagators.PiecewisePropagator
+
+    # piecewise=true with a non-piecewise method throws
+    @test_throws ErrorException init_prop(
+        Ψ,
+        Ĥ,
+        tlist;
+        method = :_non_piecewise,
+        piecewise = true
+    )
+
+    # pwc=true with a non-piecewise-constant method throws
+    @test_throws ErrorException init_prop(
+        Ψ,
+        Ĥ,
+        tlist;
+        method = :_non_piecewise,
+        pwc = true
+    )
+
+end
+
+
+@testset "init_prop unknown method" begin
+
+    tlist = collect(range(0, 10, length = 101))
+    rng = StableRNG(677918061)
+    Ψ = random_state_vector(10; rng)
+    Ĥ = random_dynamic_generator(10, tlist; rng)
+
+    @test_throws ArgumentError init_prop(Ψ, Ĥ, tlist; method = 42)
+
+end
+
+
+@testset "set_t! interior and snapping" begin
+
+    tlist = collect(range(0, 10, length = 101))
+    prop = _SimpleProp(tlist, tlist[1])
+
+    # Interior time value (the t <= tlist[1] and t >= tlist[end] branches are
+    # covered by reinit_prop! calls, but the searchsortedfirst branch is not)
+    QuantumPropagators.set_t!(prop, tlist[10])
+    @test prop.t == tlist[10]
+
+    # A value not on the grid triggers the snapping warning
+    t_off = (tlist[10] + tlist[11]) / 2
+    @test_logs (:warn, r"Snapping") QuantumPropagators.set_t!(prop, t_off)
+    @test prop.t == tlist[11]
+
+end
+
+
+@testset "_get_uniform_dt non-uniform" begin
+
+    tlist_nonuniform = [0.0, 1.0, 3.0, 6.0]
+
+    @test QuantumPropagators._get_uniform_dt(tlist_nonuniform) === nothing
+
+    @test_logs (:warn, r"Non-uniform") QuantumPropagators._get_uniform_dt(
+        tlist_nonuniform;
+        warn = true
+    )
+
+end