Add tests for rrule

Author: Simone Carlo Surace

test/rulesets/LinearAlgebra/dense.jl

@@ -161,10 +161,18 @@
     end
     @testset "kron" begin
         @testset "AbstractVecOrMat{$T}" for T in (Float64, ComplexF64)
-            test_frule(kron, randn(T, 3), randn(T, 3))
-            test_frule(kron, randn(T, 3, 2), randn(T, 3))
-            test_frule(kron, randn(T, 3), randn(T, 3, 4))
-            test_frule(kron, randn(T, 3, 4), randn(T, 2, 2))
+            @testset "frule" begin
+                test_frule(kron, randn(T, 3), randn(T, 3))
+                test_frule(kron, randn(T, 3, 2), randn(T, 3))
+                test_frule(kron, randn(T, 3), randn(T, 3, 4))
+                test_frule(kron, randn(T, 3, 4), randn(T, 2, 2))
+            end
+            @testset "rrule" begin
+                test_rrule(kron, randn(T, 3), randn(T, 3))
+                test_rrule(kron, randn(T, 3, 2), randn(T, 3))
+                test_rrule(kron, randn(T, 3), randn(T, 3, 4))
+                test_rrule(kron, randn(T, 3, 4), randn(T, 2, 2))
+            end
         end
     end
 end