fix restructure

Author: CarloLucibello

src/ArrayInterface.jl

@@ -393,6 +393,7 @@ a matching `ArrayPartition`.
 function restructure(x, y)
     out = similar(x, eltype(y))
     vec(out) .= vec(y)
+    out
 end
 
 function restructure(x::Array, y)

test/arrayinterface.jl

@@ -0,0 +1,32 @@
+@testset "restructure" begin
+    x = rand(Float32, 2, 2)
+    y = rand(4)
+    yr = ArrayInterface.restructure(x, y)
+    @test yr isa Matrix{Float64}
+    @test size(yr) == (2,2)
+    @test vec(yr) == vec(y)
+
+    @testset "views" begin
+        x = @view rand(4)[1:2]
+        y = rand(2)
+        yr = ArrayInterface.restructure(x, y)
+        @test yr isa Vector{Float64}
+        @test size(yr) == (2,)
+        @test yr == y
+
+        x = @view rand(4,4)[1:2,1:2]
+        y = rand(2,2)
+        yr = ArrayInterface.restructure(x, y)
+        @test yr isa Matrix{Float64}
+        @test size(yr) == (2,2)
+        @test yr == y
+
+
+        x = @view rand(4,4)[1]
+        y = @view rand(2,2)[1]
+        yr = ArrayInterface.restructure(x, y)
+        @test yr isa Array{Float64,0}
+        @test size(yr) == ()
+        @test yr == y
+    end
+end

test/runtests.jl

@@ -900,6 +900,9 @@ end
     @test @inferred(ArrayInterface.axes(Array{Float64}(undef, 4, 3)')) === (Base.OneTo(3),Base.OneTo(4))
 end
 
+@testset "arrayinterface" begin
+    include("arrayinterface.jl")
+end
 include("indexing.jl")
 include("dimensions.jl")