test JacobianOperator (#9)

Author: vchuravy

test/Project.toml

@@ -1,2 +1,4 @@
 [deps]
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+Enzyme = "7da242da-08ed-463a-9acd-ee780be4f1d9"
+LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

test/runtests.jl

@@ -6,12 +6,35 @@ function F!(res, x)
     return res[2] = exp(x[1] - 1) + x[2]^2 - 2
 end
 
+function F(x)
+    res = similar(x)
+    F!(res, x)
+    return res
+end
+
 let x₀ = [2.0, 0.5]
     x, stats = newton_krylov!(F!, x₀)
     @test stats.solved
 end
 
 let x₀ = [3.0, 5.0]
-    x, stats = newton_krylov!(F!, x₀)
+    x, stats = newton_krylov(F, x₀)
     @test stats.solved
 end
+
+import NewtonKrylov: JacobianOperator
+using Enzyme, LinearAlgebra
+
+@testset "Jacobian" begin
+    J_Enz = jacobian(Forward, F, [3.0, 5.0]) |> only
+    J = JacobianOperator(F!, zeros(2), [3.0, 5.0])
+    J_NK = collect(J)
+
+    @test J_NK == J_Enz
+
+    v = rand(2)
+    out = similar(v)
+    mul!(out, J, v)
+
+    @test out ≈ J_Enz * v
+end