fix test

Author: st--

test/gradcheck.jl

@@ -819,17 +819,31 @@ end
     @test back′(C̄)[1] isa Diagonal
     @test diag(back′(C̄)[1]) ≈ diag(back(C̄)[1])
   end
-  @testset "cholesky - Hermitian" begin
+  @testset "cholesky - Hermitian{Complex}" begin
     rng, N = MersenneTwister(123456), 3
     A = randn(rng, Complex{Float64}, N, N)
     H = Hermitian(A * A' + I)
     Hmat = Matrix(H)
     y, back = Zygote.pullback(cholesky, Hmat)
     y′, back′ = Zygote.pullback(cholesky, H)
     C̄ = (factors=randn(rng, N, N),)
+    @test only(back′(C̄)) isa Hermitian
+    # gradtest does not support complex gradients, even though the pullback exists
+    d = only(back(C̄))
+    d′ = only(back′(C̄))
+    @test (d + d')/2 ≈ d′
+  end
+  @testset "cholesky - Hermitian{Real}" begin
+    rng, N = MersenneTwister(123456), 3
+    A = randn(rng, N, N)
+    H = Hermitian(A * A' + I)
+    Hmat = Matrix(H)
+    y, back = Zygote.pullback(cholesky, Hmat)
+    y′, back′ = Zygote.pullback(cholesky, H)
+    C̄ = (factors=randn(rng, N, N),)
     @test back′(C̄)[1] isa Hermitian
-    @test gradtest(B->cholesky(Hermitian(B)).U, A * A' + I)
-    @test gradtest(B->logdet(cholesky(Hermitian(B))), A * A' + I)
+    @test gradtest(B->cholesky(Hermitian(B)).U, Hmat)
+    @test gradtest(B->logdet(cholesky(Hermitian(B))), Hmat)
   end
 end