@testset "Boundary.jl" begin
    @testset "BoundaryElement" begin
        be = TUG.BoundaryElement{Float64}()
        @test TUG.getType(be) == TUG.CLOSED
        @test TUG.getValue(be) == -1.0

        be = TUG.BoundaryElement{Float64}(1.0)
        @test TUG.getType(be) == TUG.CONSTANT
        @test TUG.getValue(be) == 1.0
        @test TUG.getValue([be]) == [1.0]
    end

    @testset "Boundary" begin
        grid = TUG.Grid{Float64}(25, 20, zeros(25, 20), ones(25, 20))
        boundary = TUG.Boundary{Float64}(grid)

        @test boundary.dim == 2
        @test boundary.rows == 25
        @test boundary.cols == 20

        @test TUG.getBoundaryElementType(boundary, TUG.LEFT, 1) == TUG.CLOSED
        @test TUG.getBoundaryElementType(boundary, TUG.RIGHT, 1) == TUG.CLOSED
        @test TUG.getBoundaryElementType(boundary, TUG.TOP, 1) == TUG.CLOSED
        @test TUG.getBoundaryElementType(boundary, TUG.BOTTOM, 1) == TUG.CLOSED

        @test_throws ArgumentError TUG.getBoundaryElementType(boundary, TUG.RIGHT, 26)

        @test TUG.getBoundaryElementValue(boundary, TUG.LEFT, 1) == -1.0
        @test TUG.getBoundaryElementValue(boundary, TUG.RIGHT, 1) == -1.0
        @test TUG.getBoundaryElementValue(boundary, TUG.TOP, 1) == -1.0
        @test TUG.getBoundaryElementValue(boundary, TUG.BOTTOM, 1) == -1.0

        @test_throws ArgumentError TUG.getBoundaryElementValue(boundary, TUG.TOP, 21)

        TUG.setBoundarySideClosed!(boundary, TUG.LEFT)
        TUG.setBoundarySideConstant!(boundary, TUG.RIGHT, 1.0)
        TUG.setBoundarySideConstant!(boundary, TUG.TOP, 2.0)
        TUG.setBoundarySideConstant!(boundary, TUG.BOTTOM, 3.0)

        @test TUG.getBoundaryElementType(boundary, TUG.LEFT, 1) == TUG.CLOSED
        @test TUG.getBoundaryElementType(boundary, TUG.RIGHT, 1) == TUG.CONSTANT
        @test TUG.getBoundaryElementType(boundary, TUG.TOP, 5) == TUG.CONSTANT
        @test TUG.getBoundaryElementType(boundary, TUG.BOTTOM, 20) == TUG.CONSTANT

        @test all(TUG.getValue(TUG.getBoundarySide(boundary, TUG.LEFT)) .== -1.0)
        @test all(TUG.getValue(TUG.getBoundarySide(boundary, TUG.RIGHT)) .== 1.0)
        @test all(TUG.getValue(TUG.getBoundarySide(boundary, TUG.TOP)) .== 2.0)
        @test all(TUG.getValue(TUG.getBoundarySide(boundary, TUG.BOTTOM)) .== 3.0)
    end
end