diff --git a/test/Spaces/unit_dss.jl b/test/Spaces/unit_dss.jl
new file mode 100644
index 0000000000..41c47dc699
--- /dev/null
+++ b/test/Spaces/unit_dss.jl
@@ -0,0 +1,131 @@
+#=
+julia --project
+ENV["CLIMACOMMS_DEVICE"] = "CPU";
+using Revise; include(joinpath("test", "Spaces", "unit_dss.jl"))
+=#
+using Test
+using ClimaComms
+using Random
+ClimaComms.@import_required_backends
+
+import ClimaCore:
+    Domains,
+    Fields,
+    Geometry,
+    Meshes,
+    Operators,
+    Spaces,
+    Quadratures,
+    Topologies,
+    DataLayouts
+
+function get_space_cs(::Type{FT}; context, R = 300.0) where {FT}
+    domain = Domains.SphereDomain{FT}(300.0)
+    mesh = Meshes.EquiangularCubedSphere(domain, 3)
+    topology = Topologies.Topology2D(context, mesh)
+    quad = Quadratures.GLL{4}()
+    space = Spaces.SpectralElementSpace2D(topology, quad)
+    return space
+end
+
+function one_to_n(a::AbstractArray)
+    _a = Array(a)
+    Random.seed!(1234)
+    for i in 1:length(_a)
+        _a[i] = rand()
+    end
+    return typeof(a)(_a)
+end
+
+function test_dss_count(f::Fields.Field, buff::Topologies.DSSBuffer, nc)
+    parent(f) .= one_to_n(parent(f))
+    @test allunique(parent(f))
+    cf = copy(f)
+    Spaces.weighted_dss!(f => buff)
+    n_dss_unaffected = count(parent(f) .== parent(cf))
+    n_dss_affected = length(parent(f)) - n_dss_unaffected
+    return (; n_dss_affected)
+end
+
+function get_space_and_buffers(::Type{FT}; context) where {FT}
+    init_state_covariant12(local_geometry, p) =
+        Geometry.Covariant12Vector(1.0, -1.0)
+    init_state_covariant123(local_geometry, p) =
+        Geometry.Covariant123Vector(1.0, -1.0, 1.0)
+    init_state_covariant3(local_geometry, p) = Geometry.Covariant3Vector(1.0)
+
+    R = FT(6.371229e6)
+    npoly = 2
+    z_max = FT(30e3)
+    z_elem = 3
+    h_elem = 2
+    device = ClimaComms.device(context)
+    @info "running dss-Covariant123Vector test on $(device)" h_elem z_elem npoly R z_max FT
+    # horizontal space
+    domain = Domains.SphereDomain{FT}(R)
+    horizontal_mesh = Meshes.EquiangularCubedSphere(domain, h_elem)
+    horizontal_topology = Topologies.Topology2D(
+        context,
+        horizontal_mesh,
+        Topologies.spacefillingcurve(horizontal_mesh),
+    )
+    quad = Quadratures.GLL{npoly + 1}()
+    h_space = Spaces.SpectralElementSpace2D(horizontal_topology, quad)
+    # vertical space
+    z_domain = Domains.IntervalDomain(
+        Geometry.ZPoint{FT}(zero(z_max)),
+        Geometry.ZPoint{FT}(z_max);
+        boundary_names = (:bottom, :top),
+    )
+    z_mesh = Meshes.IntervalMesh(z_domain, nelems = z_elem)
+    z_topology = Topologies.IntervalTopology(context, z_mesh)
+    z_center_space = Spaces.CenterFiniteDifferenceSpace(z_topology)
+    space = Spaces.ExtrudedFiniteDifferenceSpace(h_space, z_center_space)
+    args = (Fields.local_geometry_field(space), Ref(nothing))
+    y12 = init_state_covariant12.(args...)
+    y123 = init_state_covariant123.(args...)
+    y3 = init_state_covariant3.(args...)
+    dss_buffer = (;
+        y12 = Spaces.create_dss_buffer(y12),
+        y123 = Spaces.create_dss_buffer(y123),
+        y3 = Spaces.create_dss_buffer(y3),
+    )
+    return (; space, y12, y123, y3, dss_buffer)
+end
+
+@testset "DSS of AxisTensors on Cubed Sphere" begin
+    FT = Float64
+    device = ClimaComms.device()
+    nt = get_space_and_buffers(FT; context = ClimaComms.context(device))
+
+    # test DSS for a Covariant12Vector
+    # ensure physical velocity is continuous across SE boundary for initial state
+    n_dss_affected_y12 =
+        test_dss_count(nt.y12, nt.dss_buffer.y12, 2).n_dss_affected
+    n_dss_affected_y123 =
+        test_dss_count(nt.y123, nt.dss_buffer.y123, 3).n_dss_affected
+    n_dss_affected_y3 =
+        test_dss_count(nt.y3, nt.dss_buffer.y3, 1).n_dss_affected
+
+    @test n_dss_affected_y12 * 3 / 2 ==
+          n_dss_affected_y123 ==
+          n_dss_affected_y3 * 3
+
+    @test nt.dss_buffer.y12.scalarfidx == Int[]
+    @test nt.dss_buffer.y12.covariant12fidx == Int[1]
+    @test nt.dss_buffer.y12.contravariant12fidx == Int[]
+    @test nt.dss_buffer.y12.covariant123fidx == Int[]
+    @test nt.dss_buffer.y12.contravariant123fidx == Int[]
+
+    @test nt.dss_buffer.y123.scalarfidx == Int[]
+    @test nt.dss_buffer.y123.covariant12fidx == Int[]
+    @test nt.dss_buffer.y123.contravariant12fidx == Int[]
+    @test nt.dss_buffer.y123.covariant123fidx == Int[1]
+    @test nt.dss_buffer.y123.contravariant123fidx == Int[]
+
+    @test nt.dss_buffer.y3.scalarfidx == Int[1]
+    @test nt.dss_buffer.y3.covariant12fidx == Int[]
+    @test nt.dss_buffer.y3.contravariant12fidx == Int[]
+    @test nt.dss_buffer.y3.covariant123fidx == Int[]
+    @test nt.dss_buffer.y3.contravariant123fidx == Int[]
+end
diff --git a/test/Topologies/unit_dss_transform.jl b/test/Topologies/unit_dss_transform.jl
new file mode 100644
index 0000000000..57c6031987
--- /dev/null
+++ b/test/Topologies/unit_dss_transform.jl
@@ -0,0 +1,89 @@
+#=
+julia --project
+using Revise; include(joinpath("test", "Topologies", "unit_dss_transform.jl"))
+=#
+using Test
+using ClimaComms
+using ClimaCore.Topologies: dss_transform, dss_untransform
+using Random
+ClimaComms.@import_required_backends
+
+import ClimaCore:
+    Domains,
+    Fields,
+    Geometry,
+    Meshes,
+    Operators,
+    Spaces,
+    Quadratures,
+    Topologies,
+    DataLayouts
+
+function get_space(::Type{FT}; context) where {FT}
+    R = FT(6.371229e6)
+    npoly = 2
+    z_max = FT(30e3)
+    z_elem = 3
+    h_elem = 2
+    device = ClimaComms.device(context)
+    @info "running dss-Covariant123Vector test on $(device)" h_elem z_elem npoly R z_max FT
+    # horizontal space
+    domain = Domains.SphereDomain{FT}(R)
+    horizontal_mesh = Meshes.EquiangularCubedSphere(domain, h_elem)
+    horizontal_topology = Topologies.Topology2D(
+        context,
+        horizontal_mesh,
+        Topologies.spacefillingcurve(horizontal_mesh),
+    )
+    quad = Quadratures.GLL{npoly + 1}()
+    h_space = Spaces.SpectralElementSpace2D(horizontal_topology, quad)
+    # vertical space
+    z_domain = Domains.IntervalDomain(
+        Geometry.ZPoint{FT}(zero(z_max)),
+        Geometry.ZPoint{FT}(z_max);
+        boundary_names = (:bottom, :top),
+    )
+    z_mesh = Meshes.IntervalMesh(z_domain, nelems = z_elem)
+    z_topology = Topologies.IntervalTopology(context, z_mesh)
+    z_center_space = Spaces.CenterFiniteDifferenceSpace(z_topology)
+    space = Spaces.ExtrudedFiniteDifferenceSpace(h_space, z_center_space)
+    return space
+end
+
+@testset "dss_transform" begin
+    device = ClimaComms.device()
+    space = get_space(Float64; context = ClimaComms.context(device))
+
+    local_geometry = Fields.local_geometry_field(space)
+    map(local_geometry) do lg
+        FT = Geometry.undertype(typeof(lg))
+        (; lat, long, z) = lg.coordinates
+        # Test that vertical component is treated as a scalar:
+
+        arg = Geometry.Covariant123Vector(FT(lat), FT(long), FT(z))
+        weight = 2
+        dss_t = dss_transform(arg, lg, weight)
+        dss_ut = dss_untransform(Geometry.Covariant123Vector{FT}, dss_t, lg)
+        @test dss_t isa Geometry.UVWVector
+        @test typeof(arg) == typeof(dss_ut)
+        @test arg ≈ dss_ut / weight
+
+        arg = Geometry.Covariant12Vector(FT(lat), FT(long))
+        weight = 2
+        dss_t = dss_transform(arg, lg, weight)
+        dss_ut = dss_untransform(Geometry.Covariant12Vector{FT}, dss_t, lg)
+        @test dss_t isa Geometry.UVWVector
+        @test typeof(arg) == typeof(dss_ut)
+        @test arg ≈ dss_ut / weight
+
+        arg = Geometry.Covariant3Vector(FT(z))
+        weight = 2
+        dss_t = dss_transform(arg, lg, weight)
+        dss_ut = dss_untransform(Geometry.Covariant3Vector{FT}, dss_t, lg)
+        @test typeof(arg) == typeof(dss_ut)
+        @test dss_t isa Geometry.Covariant3Vector
+        @test dss_t === arg * weight
+        @test arg == dss_ut / weight
+        FT(1)
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index 136f5a4dfb..d8734d8ad3 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -30,8 +30,10 @@ UnitTest("Rectangle topology"                      ,"Topologies/rectangle.jl"),
 UnitTest("Rectangle surface topology"              ,"Topologies/rectangle_sfc.jl"),
 UnitTest("Cubedsphere topology"                    ,"Topologies/cubedsphere.jl"),
 UnitTest("Cubedsphere surface topology"            ,"Topologies/cubedsphere_sfc.jl"),
+UnitTest("dss_transform"                           ,"Topologies/unit_dss_transform.jl"),
 UnitTest("Quadratures"                             ,"Quadratures/Quadratures.jl"),
 UnitTest("Spaces"                                  ,"Spaces/unit_spaces.jl"),
+UnitTest("dss"                                     ,"Spaces/unit_dss.jl"),
 UnitTest("Spaces - serial CPU DSS"                 ,"Spaces/ddss1.jl"),
 UnitTest("Spaces - DSS cubed sphere"               ,"Spaces/ddss1_cs.jl"),
 UnitTest("Sphere spaces"                           ,"Spaces/sphere.jl"),