From 77b8c4d644830c993661ad46754757c05358310f Mon Sep 17 00:00:00 2001
From: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>
Date: Mon, 29 Sep 2025 18:44:50 +0200
Subject: [PATCH 1/3] test: untoggle some passing Enzyme tests

---
 .../test/Back/Enzyme/test.jl                  | 27 +++++++------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/DifferentiationInterface/test/Back/Enzyme/test.jl b/DifferentiationInterface/test/Back/Enzyme/test.jl
index 0a580badb..637309c29 100644
--- a/DifferentiationInterface/test/Back/Enzyme/test.jl
+++ b/DifferentiationInterface/test/Back/Enzyme/test.jl
@@ -1,3 +1,5 @@
+# see https://github.com/JuliaDiff/DifferentiationInterface.jl/issues/855
+
 using Pkg
 Pkg.add("Enzyme")
 
@@ -55,7 +57,7 @@ end;
     )
 
     test_differentiation(
-        backends[2],
+        backends[2:3],
         default_scenarios(;
             include_normal=false,
             include_cachified=true,
@@ -75,23 +77,19 @@ end;
 end
 
 @testset "Second order" begin
+    forward_enzyme = AutoEnzyme(; mode=Enzyme.Reverse)
+    reverse_enzyme = AutoEnzyme(; mode=Enzyme.Reverse)
     test_differentiation(
         [
             AutoEnzyme(),
-            SecondOrder(
-                AutoEnzyme(; mode=Enzyme.Reverse), AutoEnzyme(; mode=Enzyme.Forward)
-            ),
+            # SecondOrder(forward_enzyme, reverse_enzyme),  # TODO: toggle
+            SecondOrder(reverse_enzyme, forward_enzyme),
+            # SecondOrder(forward_enzyme, forward_enzyme),  # TODO: toggle
         ],
-        remove_matrix_inputs(default_scenarios(; include_constantified=true));
+        default_scenarios(; include_constantified=true, include_cachified=true);
         excluded=FIRST_ORDER,
         logging=LOGGING,
     )
-
-    test_differentiation(
-        AutoEnzyme(; mode=Enzyme.Forward);
-        excluded=vcat(FIRST_ORDER, [:hessian, :hvp]),
-        logging=LOGGING,
-    )
 end
 
 @testset "Sparse" begin
@@ -100,12 +98,7 @@ end
         if VERSION < v"1.11"
             sparse_scenarios()
         else
-            filter(sparse_scenarios()) do s
-                # for https://github.com/EnzymeAD/Enzyme.jl/issues/2168
-                (s.x isa AbstractVector) &&
-                    (s.f != DIT.sumdiffcube) &&
-                    (s.f != DIT.sumdiffcube_mat)
-            end
+            filter(s -> s.x isa AbstractVector, sparse_scenarios())
         end;
         sparsity=true,
         logging=LOGGING,

From b33ca52da6f111f940136ebdbc5accbc42e958ec Mon Sep 17 00:00:00 2001
From: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>
Date: Mon, 29 Sep 2025 18:45:35 +0200
Subject: [PATCH 2/3] Fix docs

---
 DifferentiationInterface/docs/src/explanation/backends.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/DifferentiationInterface/docs/src/explanation/backends.md b/DifferentiationInterface/docs/src/explanation/backends.md
index 845ab4b9b..efc68b20b 100644
--- a/DifferentiationInterface/docs/src/explanation/backends.md
+++ b/DifferentiationInterface/docs/src/explanation/backends.md
@@ -63,7 +63,7 @@ Moreover, each context type is supported by a specific subset of backends:
 | `AutoChainRules`           | ✅                  | ❌               |
 | `AutoDiffractor`           | ❌                  | ❌               |
 | `AutoEnzyme` (forward)     | ✅                  | ✅               |
-| `AutoEnzyme` (reverse)     | ✅                  | ❌ (soon)        |
+| `AutoEnzyme` (reverse)     | ✅                  | ✅               |
 | `AutoFastDifferentiation`  | ✅                  | ✅               |
 | `AutoFiniteDiff`           | ✅                  | ✅               |
 | `AutoFiniteDifferences`    | ✅                  | ✅               |

From 02dd8f9ed7fa95b8c31167eea6b6a44e76029a7b Mon Sep 17 00:00:00 2001
From: Guillaume Dalle <22795598+gdalle@users.noreply.github.com>
Date: Tue, 30 Sep 2025 18:40:54 +0200
Subject: [PATCH 3/3] Tests now work on matrices

---
 .../test/Back/Enzyme/test.jl                    | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/DifferentiationInterface/test/Back/Enzyme/test.jl b/DifferentiationInterface/test/Back/Enzyme/test.jl
index 637309c29..cb4fce824 100644
--- a/DifferentiationInterface/test/Back/Enzyme/test.jl
+++ b/DifferentiationInterface/test/Back/Enzyme/test.jl
@@ -16,15 +16,6 @@ check_no_implicit_imports(DifferentiationInterface)
 
 LOGGING = get(ENV, "CI", "false") == "false"
 
-function remove_matrix_inputs(scens::Vector{<:Scenario})  # TODO: remove
-    if VERSION < v"1.11"
-        return scens
-    else
-        # for https://github.com/EnzymeAD/Enzyme.jl/issues/2071
-        return filter(s -> s.x isa Union{Number,AbstractVector}, scens)
-    end
-end
-
 backends = [
     AutoEnzyme(; mode=nothing),
     AutoEnzyme(; mode=Enzyme.Forward),
@@ -77,14 +68,12 @@ end;
 end
 
 @testset "Second order" begin
-    forward_enzyme = AutoEnzyme(; mode=Enzyme.Reverse)
-    reverse_enzyme = AutoEnzyme(; mode=Enzyme.Reverse)
     test_differentiation(
         [
             AutoEnzyme(),
-            # SecondOrder(forward_enzyme, reverse_enzyme),  # TODO: toggle
-            SecondOrder(reverse_enzyme, forward_enzyme),
-            # SecondOrder(forward_enzyme, forward_enzyme),  # TODO: toggle
+            SecondOrder(
+                AutoEnzyme(; mode=Enzyme.Reverse), AutoEnzyme(; mode=Enzyme.Forward)
+            ),
         ],
         default_scenarios(; include_constantified=true, include_cachified=true);
         excluded=FIRST_ORDER,