make Divider<:Function and use just that to test mean

Author: oxinabox

test/rulesets/Statistics/statistics.jl

@@ -15,24 +15,22 @@
         test_rrule(mean, abs, [-4.0, 2.0, 2.0])
         test_rrule(mean, log, rand(3, 4) .+ 1)
         test_rrule(mean, cbrt, randn(5))
-        multiplier = Multiplier(2.0)
-        test_rrule(mean, x->multiplier(x), [2.0, 4.0, 8.0])  # defined in test_helpers.jl
-        divider = Divider(1 + rand())
-        test_rrule(mean, x->divider(x), randn(5)) 
+
+        test_rrule(mean, Divider(1 + rand()), randn(5)) # defined in test_helpers.jl
 
         test_rrule(mean, sum, [[2.0, 4.0], [4.0,1.9]]; check_inferred=false)
 
         test_rrule(mean, log, rand(ComplexF64, 5))
         test_rrule(mean, sqrt, rand(ComplexF64, 5))
-        test_rrule(mean, abs, rand(ComplexF64, 3, 4))
+        test_rrule(mean, abs, rand(ComplexF164, 3, 4))
 
         test_rrule(mean, abs, [-2.0 4.0; 5.0 1.9]; fkwargs=(;dims=1))
         test_rrule(mean, abs, [-2.0 4.0; 5.0 1.9]; fkwargs=(;dims=2))
         test_rrule(mean, sqrt, rand(ComplexF64, 3, 4); fkwargs=(;dims=(1,)))
     end
 
     @testset "Regression Test against StatsBase-like Weighted Mean" begin
-        struct DummyWeights <: AbstractVector{Float64}  # DummyType that looks like StatsBase's Weights types
+        @eval struct DummyWeights <: AbstractVector{Float64}  # DummyType that looks like StatsBase's Weights types
         end
         # This should hit the fallback "nothing" rule indicating no rule was defined
         @test nothing == rrule(ChainRulesTestUtils.TestConfig(), mean, [1.0, 2.0], DummyWeights())

test/test_helpers.jl

@@ -138,7 +138,7 @@ function ChainRulesCore.rrule(m::Multiplier, y, z)
 end
 
 """
-    Divider(x)
+    Divider(x) <: Function
 
 Stores a fixed `x` and divides by it, then squares the result.
 
@@ -148,8 +148,11 @@ julia> map(Divider(2), [1 2 3 4 10])
 1×5 Matrix{Float64}:
  0.25  1.0  2.25  4.0  25.0
 ```
+
+Unlike our other functors, this one subtypes `Function` so can be used to test things
+with that restrictiion
 """
-struct Divider{T<:Real}
+struct Divider{T<:Real} <: Function
     x::T
 end
 (d::Divider)(y::Real) = (y / d.x)^2