using Test
using MPI

MPI.Init()

function scatter_array(A, root)
    comm = MPI.COMM_WORLD
    T = eltype(A)
    if MPI.Comm_rank(comm) == root
        global B = copy(A)
    else
        global B = Array{T}(undef,1)
    end
    C = MPI.Scatter(B, 1, root, comm)
end

comm = MPI.COMM_WORLD
root = 0

A = collect(1:MPI.Comm_size(comm))
B = scatter_array(A, root)
@test B[1] == MPI.Comm_rank(comm) + 1
for typ in Base.uniontypes(MPI.MPIDatatype)

    # Allocating version
    global A = convert(Vector{typ},collect(1:MPI.Comm_size(comm)))
    global B = scatter_array(A, root)
    @test B[1] == convert(typ,MPI.Comm_rank(comm) + 1)

    # Non Allocating version
    A = convert(Vector{typ},collect(1:MPI.Comm_size(comm)))
    if MPI.Comm_rank(comm) == root
        B = copy(A)
    else
        B = Array{typ}(undef, 1)
    end
    MPI.Scatter!(A, B, 1, root, comm)
    @test B[1] == convert(typ,MPI.Comm_rank(comm) + 1)

    # In place version
    A = convert(Vector{typ},collect(1:MPI.Comm_size(comm)))
    if MPI.Comm_rank(comm) == root
        B = copy(A)
    else
        B = Array{typ}(undef, 1)
    end
    MPI.Scatter_in_place!(B, 1, root, comm)
    @test B[1] == convert(typ,MPI.Comm_rank(comm) + 1)

    # Test throwing
    B = Array{typ}(undef, 0)
    @test_throws AssertionError MPI.Scatter!(A, B, 1, root, comm)
end

MPI.Finalize()
@test MPI.Finalized()