fix sum(da; dims = :notadim) (#1116)

* move _astuple to fix sum(da; dims = :notadim)

* add tests for no op reductions

Author: tiemvanderdeure

src/array/methods.jl

@@ -18,11 +18,11 @@ for (m, f) in ((:Base, :sum), (:Base, :prod), (:Base, :maximum), (:Base, :minimu
         # Local dispatch methods
         # - Return a reduced DimArray
         @inline function $_f(A::AbstractDimArray, dims; kw...)
-            ds = _astuple(DD.dims(A, dims)) # Need to remove unused dims before `dimnum`
+            ds = DD.dims(A, _astuple(dims)) # Need to remove unused dims before `dimnum`
             rebuild(A, $m.$f(parent(A); dims=dimnum(A, ds), kw...), reducedims(A, ds))
         end
         @inline function $_f(f, A::AbstractDimArray, dims; kw...)
-            ds = _astuple(DD.dims(A, dims)) # Need to remove unused dims before `dimnum`
+            ds = DD.dims(A, _astuple(dims)) # Need to remove unused dims before `dimnum`
             rebuild(A, $m.$f(f, parent(A); dims=dimnum(A, ds), kw...), reducedims(A, ds))
         end
         # - Return a scalar

test/methods.jl

@@ -67,6 +67,11 @@ end
     @test sum(da; dims=:) == 10
     @test sum(x -> 2x, da; dims=:) == 20
 
+    @test sum(da; dims = 5) == sum(da; dims = :notadim) == 
+        sum(da; dims = (:notadim,)) == da
+    @test maximum(da; dims = 5) == maximum(da; dims = :notadim) == 
+        maximum(da; dims = (:notadim,)) == da
+
     a = [1 2; 3 4]
     dimz = X(143:2:145), Y(-38:2:-36)
     da = DimArray(a, dimz)