Add comment on complex, extend Dual number testset

Author: DomCRose

ext/NNlibCUDA/test/activations.jl

@@ -7,23 +7,16 @@
 end
 
 @testset "forward diff" begin
-    f = (x) -> logσ.(x)
-    ds = Dual.(rand(5),1)
-    @test f(ds) ≈ collect(f(CuArray(ds)))
-    f = (x) -> tanh.(x)
-    ds = Dual.(rand(5),1)
-    @test f(ds) ≈ collect(f(CuArray(ds)))
-    f = (x) -> σ.(x)
-    ds = Dual.(rand(5),1)
-    @test f(ds) ≈ collect(f(CuArray(ds)))
-    f = (x) -> elu.(x)
-    ds = Dual.(rand(5),1)
-    @test f(ds) ≈ collect(f(CuArray(ds)))
-    f = (x) -> relu.(x)
-    ds = Dual.(rand(5),1)
-    @test f(ds) ≈ collect(f(CuArray(ds)))
+    for f in NNlib.ACTIVATIONS
+        if f ∉ [:rrelu]
+            @eval gputest(x -> $f.(x), Dual.(rand(5), 1))
+        end
+    end
 end
 
+# Broadcasting over complex CuArray works without NNlibCUDA, this test checks that
+# NNlibCUDA does not cause such operations to take a fast path which does not support
+# complex numbers (e.g. CUDNN)
 @testset "complex" begin
     f(x) = tanh.(x)
     cs = rand(ComplexF64, 5)