Fix #141 (#142)

Author: dlfivefifty

src/blockreduce.jl

@@ -16,3 +16,6 @@ Base.mapfoldl(f::F, op::OP, B::PseudoBlockArray; kw...) where {F, OP} =
 
 Base.mapreduce(f::F, op::OP, B::PseudoBlockArray; kw...) where {F, OP} =
     mapreduce(f, op, B.blocks; kw...)
+
+# support sum, need to return something analoguous to Base.OneTo(1) but same type
+Base.reduced_index(::BR) where BR<:BlockedUnitRange = convert(BR, Base.OneTo(1))

test/test_blockreduce.jl

@@ -15,3 +15,13 @@ end
     x = PseudoBlockVector(rand(Int, 3), [1, 2])
     @test reduce(+, x) == sum(collect(x))
 end
+
+@testset "sum (#141)" begin
+    data = reshape(collect(1:20), 4, 5)
+    A = BlockArray(data, [1,3], [2,3])
+    @test sum(A) == sum(data)
+    @test sum(A; dims=1) == sum(data; dims=1)
+    @test sum(A; dims=2) == sum(data; dims=2)
+    @test blockisequal(axes(A,2), axes(sum(A; dims=1),2))
+    @test blockisequal(axes(A,1), axes(sum(A; dims=2),1))
+end