test adjoint

Author: mcabbott

src/projection.jl

@@ -222,7 +222,7 @@ function (project::ProjectTo{AbstractArray})(dx::AbstractArray{S,M}) where {S,M}
     return dz
 end
 
-# Trivial case -- won't collapse Any[NoTangent(), NoTangent()]
+# Trivial case, this won't collapse Any[NoTangent(), NoTangent()] but that's OK.
 (project::ProjectTo{AbstractArray})(dx::AbstractArray{<:AbstractZero}) = NoTangent()
 
 # Row vectors aren't acceptable as gradients for 1-row matrices:

test/projection.jl

@@ -164,6 +164,9 @@ Base.zero(x::Dual) = Dual(zero(x.value), zero(x.partial))
             @test pvecmat(collect.(zs)) == zs
             @test pvecmat(collect.(zs)) isa LinearAlgebra.AdjOrTransAbsVec
         end
+
+        # issue #410
+        @test padj([NoTangent() NoTangent() NoTangent()]) === NoTangent()
     end
 
     @testset "LinearAlgebra: dense structured matrices" begin