more tests

test/bias_act.jl

@@ -1,4 +1,4 @@
-using NNlib, Zygote, Test
+using NNlib, Zygote, ChainRulesCore, Test
 using Zygote: ForwardDiff
 
 ACTIVATION_FUNCTIONS =
@@ -14,14 +14,21 @@ ACTIVATION_FUNCTIONS =
     @test @inferred(bias_act!(tanh, copy(x), false)) ≈ tanh.(x)
 
     # Check that it does overwrite:
-    x32 = rand(Float32, 3, 4)
-    x32copy = copy(x32)
+    x32 = rand(Float32, 3, 4); x32copy = copy(x32)
     @test @inferred(bias_act!(cbrt, x32, b)) ≈ cbrt.(x32copy .+ b)
-    @test x32  ≈ cbrt.(x32copy .+ b)
-    x32 = rand(Float32, 3, 4)
-    x32copy = copy(x32)
+    @test x32 ≈ cbrt.(x32copy .+ b)
+
+    x32 = rand(Float32, 3, 4); x32copy = copy(x32)  # without bias
     @test @inferred(bias_act!(tanh, x32, false)) ≈ tanh.(x32copy)
-    @test x32  ≈ tanh.(x32copy)
+    @test x32 ≈ tanh.(x32copy)
+
+    x32 = rand(Float32, 3, 4); x32copy = copy(x32)  # now check gradient rule
+    y, back = rrule(Zygote.ZygoteRuleConfig(), bias_act!, relu, x32, b)
+    @test y ≈ x32 ≈ relu.(x32copy .+ b)
+
+    x32 = rand(Float32, 3, 4); x32copy = copy(x32)  # without bias
+    y, back = rrule(Zygote.ZygoteRuleConfig(), bias_act!, relu, x32, false)
+    @test y ≈ x32 ≈ relu.(x32copy)
 
     # Check that it doesn't try to overwrite non-float arrays:
     xint = rand(-3:3, 3, 4)
@@ -78,7 +85,7 @@ ACTIVATION_FUNCTIONS =
         g2 = ForwardDiff.gradient(x) do x
             sum(abs2, Zygote.gradient(x -> sum(abs2, bias_act!(relu, copy(x), b)), x)[1])
         end
-        @test_broken gx ≈ Zygote.gradient(x) do x
+        @test_skip gx ≈ Zygote.gradient(x) do x  # Here global variable b causes an error
             sum(abs2,Zygote. gradient(x -> sum(abs2, bias_act!(relu, copy(x), b)), x)[1])
         end
         # Can't differentiate foreigncall expression $(Expr(:foreigncall, :(:jl_eqtable_get), Any, svec(Any, Any, Any), 0, :(:ccall), %5, %3, %4)).