Fix

Author: gdalle

DifferentiationInterface/ext/DifferentiationInterfaceFiniteDiffExt/onearg.jl

@@ -462,11 +462,19 @@ function DI.prepare_hessian_nokwarg(
     end
     relstep_h = if isnothing(backend.relstep)
         default_relstep(fdhtype(backend), eltype(x))
+    else
+        backend.relstep
+    end
+    absstep_g = if isnothing(backend.absstep)
+        relstep_g
+    else
+        backend.absstep
+    end
+    absstep_h = if isnothing(backend.absstep)
+        relstep_h
     else
         backend.absstep
     end
-    absstep_g = isnothing(backend.absstep) ? relstep_g : backend.absstep
-    absstep_h = isnothing(backend.absstep) ? relstep_h : backend.absstep
     return FiniteDiffHessianPrep(
         _sig, gradient_cache, hessian_cache, relstep_g, absstep_g, relstep_h, absstep_h
     )

DifferentiationInterface/test/Back/FiniteDiff/test.jl

@@ -88,6 +88,11 @@ end;
         @test prep.relstep == 0.1
         @test prep.absstep == 1000
     end
+    prep = prepare_hessian(sum, backend, [1.0])
+    @test prep.absstep_g == 1000
+    @test prep.absstep_h == 1000
+    @test prep.relstep_g == 0.1
+    @test prep.relstep_h == 0.1
 
     backend = AutoFiniteDiff(; relstep=0.1)
     preps = [
@@ -103,4 +108,9 @@ end;
         @test prep.relstep == 0.1
         @test prep.absstep == 0.1
     end
+    prep = prepare_hessian(sum, backend, [1.0])
+    @test prep.absstep_g == 0.1
+    @test prep.absstep_h == 0.1
+    @test prep.relstep_g == 0.1
+    @test prep.relstep_h == 0.1
 end