include("common.jl")

MPI.Init()

comm = MPI.COMM_WORLD
root = 0
rank = MPI.Comm_rank(comm)
sz   = MPI.Comm_size(comm)
isroot = MPI.Comm_rank(comm) == root

for T in MPITestTypes

    # Allocating
    A = ArrayType{T}(fill(T(rank+1), 4))
    synchronize()
    C = MPI.Gather(A, comm; root=root)
    if isroot
        @test C isa ArrayType{T}
        @test C == ArrayType{T}(repeat(1:sz, inner=4))
    end

    # Allocating, object
    C = MPI.Gather(T(rank+1), comm; root=root)
    if isroot
        @test C isa Vector{T}
        @test C == Vector{T}(1:sz)
    else
        @test C === nothing
    end

    # Allocating, array
    A = ArrayType{T}([MPI.Comm_rank(comm) + 1])
    synchronize()
    C = MPI.Gather(A, comm; root=root)
    if isroot
        @test C isa ArrayType{T}
        @test C == ArrayType{T}(1:MPI.Comm_size(comm))
    else
        @test C === nothing
    end

    # Allocating, view
    A = ArrayType{T}([MPI.Comm_rank(comm) + 1, 0])
    synchronize()
    C = MPI.Gather(view(A, 1:1), comm; root=root)
    if isroot
        @test C isa ArrayType{T}
        @test C == ArrayType{T}(1:MPI.Comm_size(comm))
    end

    # Non Allocating
    A = ArrayType{T}(fill(T(rank+1), 4))
    synchronize()
    C = ArrayType{T}(undef, 4sz)
    MPI.Gather!(A, C, comm; root=root)
    if isroot
        @test C == ArrayType{T}(repeat(1:sz, inner=4))
    end
    MPI.Gather!(A, UBuffer(C,4), comm; root=root)
    if isroot
        @test C == ArrayType{T}(repeat(1:sz, inner=4))
    end

    # In_place
    A = ArrayType{T}(fill(T(rank+1), 4))
    if isroot
        A = ArrayType{T}(fill(T(rank+1), 4*sz))
    end
    synchronize()
    if root == MPI.Comm_rank(comm)
        MPI.Gather!(MPI.IN_PLACE, UBuffer(A,4), comm; root=root)
    else
        MPI.Gather!(A, nothing, comm; root=root)
    end
    if isroot
        @test A == ArrayType{T}(repeat(1:sz, inner=4))
    end

end

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