From 91c7b5a3085fb543d51eadf91e72b8f65996e96a Mon Sep 17 00:00:00 2001
From: oameye <orjan.ameye@hotmail.com>
Date: Mon, 25 Mar 2024 09:51:00 +0100
Subject: [PATCH] add StochSystem unit tests

---
 test/stochsystem.jl | 81 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/test/stochsystem.jl b/test/stochsystem.jl
index 2eb86db0..731df1fb 100644
--- a/test/stochsystem.jl
+++ b/test/stochsystem.jl
@@ -1,4 +1,5 @@
 using CriticalTransitions, StaticArrays
+CT = CriticalTransitions
 
 function meier_stein(u, p, t) # out-of-place
     x, y = u
@@ -13,3 +14,83 @@ sys = StochSystem(meier_stein, [], zeros(2))
 tspan = (0.0, 100.0)
 prob = ODEProblem{false}(meier_stein, SA[0.0, 0.0], tspan, ())
 kpo = CoupledODEs(prob) # DynamicalSystems method
+
+using Test
+
+# Test StochSystem constructors
+@testset "StochSystem constructors" begin
+    f(x,p,t) = x^2
+    sys1 = StochSystem(f, [1], [0])
+    @test sys1.f(2, sys1.pf, 0) == 4
+    @test sys1.u == [0]
+    @test sys1.σ == 0.0
+    @test sys1.g == idfunc
+    @test sys1.pg == nothing
+    @test sys1.Σ == I(1)
+    @test sys1.process == "WhiteGauss"
+
+    sys2 = StochSystem(f, [1], [0], 0.5)
+    @test sys2.f(2, sys2.pf, 0) == 4
+    @test sys2.u == [0]
+    @test sys2.σ == 0.5
+    @test sys2.g == idfunc
+    @test sys2.pg == nothing
+    @test sys2.Σ == I(1)
+    @test sys2.process == "WhiteGauss"
+
+    Σ = [true false; false true]
+    sys3 = StochSystem(f, [1], [0], 0.5, Σ)
+    @test sys3.f(2, sys3.pf, 0) == 4
+    @test sys3.u == [0]
+    @test sys3.σ == 0.5
+    @test sys3.g == idfunc
+    @test sys3.pg == nothing
+    @test sys3.Σ == Σ
+    @test sys3.process == "WhiteGauss"
+end
+
+# Test drift function
+@testset "drift" begin
+    f(x,p,t) = x.^2
+    sys = StochSystem(f, [1], [0])
+    @test drift(sys, [2]) == [4]
+end
+
+# Test σg function
+@testset "σg" begin
+    f(x,p,t) = x^2
+    sys = StochSystem(f, [1], [0], 0.5)
+    @test CT.σg(sys)(2, sys.pf, 0) == 0.5 .* CT.idfunc(2, sys.pf, 0)
+end
+
+# Test p function
+@testset "p" begin
+    f(x,p,t) = x^2
+    sys = StochSystem(f, [1], [0], 0.5)
+    @test CT.p(sys) == [[1], nothing]
+end
+
+# Test CoupledODEs function
+@testset "CoupledODEs" begin
+    f(x,p,t) = x.^2
+    sys = StochSystem(f, [1.0], [0.0], 0.5)
+    cds = CoupledODEs(sys)
+    @test cds.integ.f([2], sys.pf, 0) == [4]
+    @test cds.integ.u == [0]
+    @test cds.p0 == sys.pf
+end
+
+
+# Test StochSystem conversion from CoupledODEs
+@testset "StochSystem from CoupledODEs" begin
+    f(x,p,t) = x.^2
+    cds = CoupledODEs(f, [0.0], [0.0])
+    sys = StochSystem(cds, 0.5, idfunc, nothing, I(1), "WhiteGauss")
+    @test sys.f([2], sys.pf, 0) == [4]
+    @test sys.u == [0]
+    @test sys.σ == 0.5
+    @test sys.g == idfunc
+    @test sys.pg == nothing
+    @test sys.Σ == I(1)
+    @test sys.process == "WhiteGauss"
+end