diff --git a/docs/src/fieldexchanger.md b/docs/src/fieldexchanger.md
index 663770cc2..733905434 100644
--- a/docs/src/fieldexchanger.md
+++ b/docs/src/fieldexchanger.md
@@ -13,8 +13,6 @@ The component models are updated by broadcasting the coupler fields, via the `up
 
 If an `update_field!` function is not defined for a particular component model, it will be ignored.
 
-Each component model is also required to define its own `step!` and `reinit!` functions, otherwise this will be ignored.
-
 ## FieldExchanger API
 
 ```@docs
@@ -25,11 +23,3 @@ Each component model is also required to define its own `step!` and `reinit!` fu
     ClimaCoupler.FieldExchanger.reinit_model_sims!
     ClimaCoupler.FieldExchanger.step_model_sims!
 ```
-
-
-## FieldExchanger Internal Functions
-
-```@docs
-    ClimaCoupler.FieldExchanger.step!
-    ClimaCoupler.FieldExchanger.reinit!
-```
diff --git a/docs/src/interfacer.md b/docs/src/interfacer.md
index 1e237d5cd..be170d284 100644
--- a/docs/src/interfacer.md
+++ b/docs/src/interfacer.md
@@ -163,7 +163,8 @@ module docs for more information.
 - `SurfaceStub` is a `SurfaceModelSimulation`, but it only contains
 required data in `<surface_stub>.cache`, e.g., for the calculation
 of surface fluxes through a prescribed surface state. The above
-adapter functions are already predefined for `SurfaceStub`, with
+adapter functions are already predefined for `SurfaceStub`
+in the `surface_stub.jl` file, with
 the cache variables specified as:
 ```
 get_field(sim::SurfaceStub, ::Val{:air_density}) = sim.cache.ρ_sfc
diff --git a/experiments/AMIP/components/atmosphere/climaatmos.jl b/experiments/AMIP/components/atmosphere/climaatmos.jl
index 27f64a5f4..ab3c28e58 100644
--- a/experiments/AMIP/components/atmosphere/climaatmos.jl
+++ b/experiments/AMIP/components/atmosphere/climaatmos.jl
@@ -17,9 +17,9 @@ import ClimaCoupler.FluxCalculator:
     extrapolate_ρ_to_sfc,
     get_surface_params,
     water_albedo_from_atmosphere!
-import ClimaCoupler.Interfacer: get_field, update_field!, name
+import ClimaCoupler.Interfacer: get_field, update_field!, name, step!, reinit!
 import ClimaCoupler.Checkpointer: get_model_prog_state
-import ClimaCoupler.FieldExchanger: update_sim!, step!, reinit!
+import ClimaCoupler.FieldExchanger: update_sim!
 import ClimaCoupler.Utilities: swap_space!
 
 include("climaatmos_extra_diags.jl")
diff --git a/experiments/AMIP/components/land/climaland_bucket.jl b/experiments/AMIP/components/land/climaland_bucket.jl
index 916e20b57..58669d37c 100644
--- a/experiments/AMIP/components/land/climaland_bucket.jl
+++ b/experiments/AMIP/components/land/climaland_bucket.jl
@@ -18,8 +18,7 @@ using ClimaLand:
     CoupledAtmosphere
 import ClimaLand.Parameters as LP
 
-import ClimaCoupler.Interfacer: LandModelSimulation, get_field, update_field!, name
-import ClimaCoupler.FieldExchanger: step!, reinit!
+import ClimaCoupler.Interfacer: LandModelSimulation, get_field, update_field!, name, step!, reinit!
 import ClimaCoupler.FluxCalculator: update_turbulent_fluxes_point!, surface_thermo_state
 
 ###
diff --git a/experiments/AMIP/components/ocean/eisenman_seaice.jl b/experiments/AMIP/components/ocean/eisenman_seaice.jl
index 75ac89f91..9732df570 100644
--- a/experiments/AMIP/components/ocean/eisenman_seaice.jl
+++ b/experiments/AMIP/components/ocean/eisenman_seaice.jl
@@ -7,8 +7,7 @@ import ClimaTimeSteppers as CTS
 import ClimaCoupler: FluxCalculator
 import ClimaCoupler.FluxCalculator:
     update_turbulent_fluxes_point!, differentiate_turbulent_fluxes!, surface_thermo_state
-import ClimaCoupler.Interfacer: get_field, update_field!
-import ClimaCoupler.FieldExchanger: step!, reinit!
+import ClimaCoupler.Interfacer: get_field, update_field!, step!, reinit!
 
 ###
 ### Functions required by ClimaCoupler.jl for a SurfaceModelSimulation
diff --git a/experiments/AMIP/components/ocean/prescr_seaice.jl b/experiments/AMIP/components/ocean/prescr_seaice.jl
index 47807fa5c..a255c0b90 100644
--- a/experiments/AMIP/components/ocean/prescr_seaice.jl
+++ b/experiments/AMIP/components/ocean/prescr_seaice.jl
@@ -4,8 +4,7 @@ using ClimaCore
 import ClimaTimeSteppers as CTS
 import Thermodynamics as TD
 
-import ClimaCoupler.Interfacer: SeaIceModelSimulation, get_field, update_field!, name
-import ClimaCoupler.FieldExchanger: step!, reinit!
+import ClimaCoupler.Interfacer: SeaIceModelSimulation, get_field, update_field!, name, step!, reinit!
 import ClimaCoupler.FluxCalculator: update_turbulent_fluxes_point!
 using ClimaCoupler: Regridder
 import ClimaCoupler.Utilities: swap_space!
diff --git a/experiments/AMIP/components/ocean/slab_ocean.jl b/experiments/AMIP/components/ocean/slab_ocean.jl
index fa03a7471..d3e1d394a 100644
--- a/experiments/AMIP/components/ocean/slab_ocean.jl
+++ b/experiments/AMIP/components/ocean/slab_ocean.jl
@@ -2,8 +2,7 @@ import SciMLBase: ODEProblem, init
 
 using ClimaCore
 import ClimaTimeSteppers as CTS
-import ClimaCoupler.Interfacer: OceanModelSimulation, get_field, update_field!, name
-import ClimaCoupler.FieldExchanger: step!, reinit!
+import ClimaCoupler.Interfacer: OceanModelSimulation, get_field, update_field!, name, step!, reinit!
 import ClimaCoupler.FluxCalculator: update_turbulent_fluxes_point!
 import ClimaCoupler.Utilities: swap_space!
 import ClimaCoupler.BCReader: float_type_bcf
diff --git a/experiments/AMIP/coupler_driver.jl b/experiments/AMIP/coupler_driver.jl
index f6ee47e17..6e554f91e 100644
--- a/experiments/AMIP/coupler_driver.jl
+++ b/experiments/AMIP/coupler_driver.jl
@@ -60,7 +60,7 @@ using ClimaCoupler.FluxCalculator:
     MoninObukhovScheme,
     partitioned_turbulent_fluxes!,
     water_albedo_from_atmosphere!
-using ClimaCoupler.Interfacer: CoupledSimulation, SurfaceStub, get_field, update_field!
+using ClimaCoupler.Interfacer: CoupledSimulation, SurfaceStub, get_field, update_field!, step!
 using ClimaCoupler.Regridder
 using ClimaCoupler.Regridder: update_surface_fractions!, combine_surfaces!, binary_mask
 using ClimaCoupler.TimeManager:
diff --git a/src/FieldExchanger.jl b/src/FieldExchanger.jl
index c38558415..ef4dad3fb 100644
--- a/src/FieldExchanger.jl
+++ b/src/FieldExchanger.jl
@@ -6,11 +6,11 @@ atmospheric and surface component models.
 """
 module FieldExchanger
 
-import SciMLBase: step!, reinit!
 export import_atmos_fields!,
     import_combined_surface_fields!, update_sim!, update_model_sims!, reinit_model_sims!, step_model_sims!
 
 using ClimaCoupler: Interfacer, FluxCalculator, Regridder, Utilities
+import ClimaCoupler.Interfacer: step!, reinit!
 
 """
     import_atmos_fields!(csf, model_sims, boundary_space, turbulent_fluxes)
@@ -148,14 +148,6 @@ function update_sim!(sim::Interfacer.SurfaceModelSimulation, csf, turbulent_flux
     Interfacer.update_field!(sim, Val(:snow_precipitation), csf.P_snow)
 end
 
-"""
-    update_sim!(::SurfaceStub, csf, area_fraction)
-
-The stub surface simulation only updates the air density (needed for the turbulent flux calculation).
-"""
-function update_sim!(sim::Interfacer.SurfaceStub, csf, area_fraction)
-    Interfacer.update_field!(sim, Val(:air_density), csf.ρ_sfc)
-end
 """
     update_model_sims!(model_sims, csf, turbulent_fluxes)
 
@@ -192,13 +184,6 @@ function reinit_model_sims!(model_sims)
     end
 end
 
-"""
-    reinit!(cs::SurfaceStub)
-
-The stub surface simulation is not updated by this function. Extends `SciMLBase.reinit!`.
-"""
-reinit!(::Interfacer.SurfaceStub) = nothing
-
 """
     step_model_sims!(model_sims, t)
 
@@ -214,11 +199,4 @@ function step_model_sims!(model_sims, t)
     end
 end
 
-"""
-    step!(::SurfaceStub, t)
-
-The stub surface simulation is not updated by this function. Extends `SciMLBase.step!`.
-"""
-step!(::Interfacer.SurfaceStub, _) = nothing
-
 end # module
diff --git a/src/FluxCalculator.jl b/src/FluxCalculator.jl
index b8a924cc0..1858960fd 100644
--- a/src/FluxCalculator.jl
+++ b/src/FluxCalculator.jl
@@ -377,8 +377,6 @@ function update_turbulent_fluxes_point!(
     )
 end
 
-update_turbulent_fluxes_point!(sim::Interfacer.SurfaceStub, fields::NamedTuple, colidx::Fields.ColumnIndex) = nothing
-
 """
     differentiate_turbulent_fluxes!(sim::Interfacer.SurfaceModelSimulation, args)
 
diff --git a/src/Interfacer.jl b/src/Interfacer.jl
index 530b123d0..9f87eb0fe 100644
--- a/src/Interfacer.jl
+++ b/src/Interfacer.jl
@@ -5,6 +5,7 @@ This modules contains abstract types, interface templates and model stubs for co
 """
 module Interfacer
 import Thermodynamics as TD
+import SciMLBase: step!, reinit!
 
 using ClimaCore: Fields
 export CoupledSimulation,
@@ -12,13 +13,15 @@ export CoupledSimulation,
     ComponentModelSimulation,
     AtmosModelSimulation,
     SurfaceModelSimulation,
-    SurfaceStub,
     SeaIceModelSimulation,
     LandModelSimulation,
     OceanModelSimulation,
     name,
     get_field,
-    update_field!
+    update_field!,
+    SurfaceStub,
+    step!,
+    reinit!
 
 
 """
@@ -163,41 +166,6 @@ get_field(sim::ComponentModelSimulation, val::Val) = get_field_error(sim, val)
 
 get_field_error(sim, val::Val{X}) where {X} = error("undefined field `$X` for " * name(sim))
 
-
-"""
-    SurfaceStub
-
-On object containing simulation-like info, used as a stub or for prescribed data.
-"""
-struct SurfaceStub{I} <: SurfaceModelSimulation
-    cache::I
-end
-
-"""
-    stub_init(cache)
-
-Initialization function for SurfaceStub simulation type.
-"""
-stub_init(cache) = SurfaceStub(cache)
-
-"""
-    get_field(::SurfaceStub, ::Val)
-
-A getter function, that should not allocate. If undefined, it returns a descriptive error.
-"""
-get_field(sim::SurfaceStub, ::Val{:air_density}) = sim.cache.ρ_sfc
-get_field(sim::SurfaceStub, ::Val{:area_fraction}) = sim.cache.area_fraction
-get_field(sim::SurfaceStub, ::Val{:beta}) = sim.cache.beta
-get_field(sim::SurfaceStub, ::Val{:energy}) = nothing
-get_field(sim::SurfaceStub, ::Val{:roughness_buoyancy}) = sim.cache.z0b
-get_field(sim::SurfaceStub, ::Val{:roughness_momentum}) = sim.cache.z0m
-get_field(sim::SurfaceStub, ::Val{:surface_direct_albedo}) = sim.cache.α_direct
-get_field(sim::SurfaceStub, ::Val{:surface_diffuse_albedo}) = sim.cache.α_diffuse
-get_field(sim::SurfaceStub, ::Val{:surface_humidity}) =
-    TD.q_vap_saturation_generic.(sim.cache.thermo_params, sim.cache.T_sfc, sim.cache.ρ_sfc, sim.cache.phase)
-get_field(sim::SurfaceStub, ::Val{:surface_temperature}) = sim.cache.T_sfc
-get_field(sim::SurfaceStub, ::Val{:water}) = nothing
-
 """
     get_field(::ComponentModelSimulation, ::Val, colidx::Fields.ColumnIndex)
 
@@ -257,32 +225,38 @@ update_field_warning(sim, val::Val{X}) where {X} =
     @warn("`update_field!` is not extended for the `$X` field of " * name(sim) * ": skipping update.", maxlog = 1)
 
 """
-    update_field!(sim::SurfaceStub, ::Val{:area_fraction}, field::Fields.Field)
+    name(::ComponentModelSimulation)
 
-Updates the specified value in the cache of `SurfaceStub`.
+Returns simulation name, if defined, or `Unnamed` if not.
 """
-function update_field!(sim::SurfaceStub, ::Val{:area_fraction}, field::Fields.Field)
-    sim.cache.area_fraction .= field
-end
-function update_field!(sim::SurfaceStub, ::Val{:surface_temperature}, field::Fields.Field)
-    sim.cache.T_sfc .= field
-end
-function update_field!(sim::SurfaceStub, ::Val{:air_density}, field)
-    parent(sim.cache.ρ_sfc) .= parent(field)
-end
-function update_field!(sim::SurfaceStub, ::Val{:surface_direct_albedo}, field::Fields.Field)
-    sim.cache.α_direct .= field
-end
-function update_field!(sim::SurfaceStub, ::Val{:surface_diffuse_albedo}, field::Fields.Field)
-    sim.cache.α_diffuse .= field
-end
+name(::ComponentModelSimulation) = "Unnamed"
 
 """
-    name(::ComponentModelSimulation)
+    step!(sim::ComponentModelSimulation, t)
 
-Returns simulation name, if defined, or `Unnamed` if not.
+A function to update the simulation in-place with values calculate for time `t`.
+For the models we currently have implemented, this is a simple wrapper around
+the `step!` function implemented in SciMLBase.jl.
+
+This must be extended for all component models - otherwise this default
+function will be called and an error will be raised.
 """
-name(::ComponentModelSimulation) = "Unnamed"
-name(::SurfaceStub) = "SurfaceStub"
+step!(sim::ComponentModelSimulation, t) = error("undefined step! for " * name(sim))
+
+"""
+    reinit!(sim::ComponentModelSimulation)
+
+A function to restart a simulation after solving of the simulation has been
+paused or interrupted. Like `step!`, this is currently a simple wrapper
+around the `reinit!` function of SciMLBase.jl.
+
+This must be extended for all component models - otherwise this default
+function will be called and an error will be raised.
+"""
+reinit!(sim::ComponentModelSimulation) = error("undefined reinit! for " * name(sim))
+
+
+# Include file containing the surface stub simulation type.
+include("surface_stub.jl")
 
 end # module
diff --git a/src/surface_stub.jl b/src/surface_stub.jl
new file mode 100644
index 000000000..dc66f6f11
--- /dev/null
+++ b/src/surface_stub.jl
@@ -0,0 +1,94 @@
+"""
+    SurfaceStub
+
+On object containing simulation-like info, used as a stub or for prescribed data.
+"""
+struct SurfaceStub{I} <: SurfaceModelSimulation
+    cache::I
+end
+
+"""
+    stub_init(cache)
+
+Initialization function for SurfaceStub simulation type.
+"""
+stub_init(cache) = SurfaceStub(cache)
+
+## Extensions of Interfacer.jl functions
+
+"""
+    get_field(::SurfaceStub, ::Val)
+
+A getter function, that should not allocate. If undefined, it returns a descriptive error.
+"""
+get_field(sim::SurfaceStub, ::Val{:air_density}) = sim.cache.ρ_sfc
+get_field(sim::SurfaceStub, ::Val{:area_fraction}) = sim.cache.area_fraction
+get_field(sim::SurfaceStub, ::Val{:beta}) = sim.cache.beta
+get_field(sim::SurfaceStub, ::Val{:energy}) = nothing
+get_field(sim::SurfaceStub, ::Val{:roughness_buoyancy}) = sim.cache.z0b
+get_field(sim::SurfaceStub, ::Val{:roughness_momentum}) = sim.cache.z0m
+get_field(sim::SurfaceStub, ::Val{:surface_direct_albedo}) = sim.cache.α_direct
+get_field(sim::SurfaceStub, ::Val{:surface_diffuse_albedo}) = sim.cache.α_diffuse
+get_field(sim::SurfaceStub, ::Val{:surface_humidity}) =
+    TD.q_vap_saturation_generic.(sim.cache.thermo_params, sim.cache.T_sfc, sim.cache.ρ_sfc, sim.cache.phase)
+get_field(sim::SurfaceStub, ::Val{:surface_temperature}) = sim.cache.T_sfc
+get_field(sim::SurfaceStub, ::Val{:water}) = nothing
+
+"""
+    update_field!(sim::SurfaceStub, ::Val{:area_fraction}, field::Fields.Field)
+
+Updates the specified value in the cache of `SurfaceStub`.
+"""
+function update_field!(sim::SurfaceStub, ::Val{:area_fraction}, field::Fields.Field)
+    sim.cache.area_fraction .= field
+end
+function update_field!(sim::SurfaceStub, ::Val{:surface_temperature}, field::Fields.Field)
+    sim.cache.T_sfc .= field
+end
+function update_field!(sim::SurfaceStub, ::Val{:air_density}, field)
+    parent(sim.cache.ρ_sfc) .= parent(field)
+end
+function update_field!(sim::SurfaceStub, ::Val{:surface_direct_albedo}, field::Fields.Field)
+    sim.cache.α_direct .= field
+end
+function update_field!(sim::SurfaceStub, ::Val{:surface_diffuse_albedo}, field::Fields.Field)
+    sim.cache.α_diffuse .= field
+end
+
+"""
+    name(::ComponentModelSimulation)
+
+Returns simulation name, if defined, or `Unnamed` if not.
+"""
+name(::SurfaceStub) = "SurfaceStub"
+
+
+## Extensions of FieldExchanger.jl functions
+
+"""
+    update_sim!(::SurfaceStub, csf, area_fraction)
+
+The stub surface simulation only updates the air density (needed for the turbulent flux calculation).
+"""
+function update_sim!(sim::SurfaceStub, csf, area_fraction)
+    update_field!(sim, Val(:air_density), csf.ρ_sfc)
+end
+
+"""
+    reinit!(cs::SurfaceStub)
+
+The stub surface simulation is not updated by this function. Extends `SciMLBase.reinit!`.
+"""
+reinit!(::SurfaceStub) = nothing
+
+"""
+    step!(::SurfaceStub, t)
+
+The stub surface simulation is not updated by this function. Extends `SciMLBase.step!`.
+"""
+step!(::SurfaceStub, _) = nothing
+
+
+## Extensions of FluxCalculator.jl functions
+
+update_turbulent_fluxes_point!(sim::SurfaceStub, fields::NamedTuple, colidx::Fields.ColumnIndex) = nothing
diff --git a/test/component_model_tests/eisenman_seaice_tests.jl b/test/component_model_tests/eisenman_seaice_tests.jl
index 53957ca60..75edbc04f 100644
--- a/test/component_model_tests/eisenman_seaice_tests.jl
+++ b/test/component_model_tests/eisenman_seaice_tests.jl
@@ -5,7 +5,7 @@ using ClimaCore: Fields, Spaces
 
 import ClimaCoupler
 import ClimaCoupler.TestHelper
-import ClimaCoupler.Interfacer: SeaIceModelSimulation
+import ClimaCoupler.Interfacer: SeaIceModelSimulation, step!
 import ClimaCoupler: Regridder
 
 import ClimaParams as CP
diff --git a/test/field_exchanger_tests.jl b/test/field_exchanger_tests.jl
index d3fca071a..970331e23 100644
--- a/test/field_exchanger_tests.jl
+++ b/test/field_exchanger_tests.jl
@@ -2,16 +2,11 @@ using Test
 using ClimaCore: Meshes, Domains, Topologies, Spaces, Fields, InputOutput
 using ClimaCoupler: Utilities, Regridder, TestHelper
 import ClimaCoupler.Interfacer:
-    update_field!, AtmosModelSimulation, SurfaceModelSimulation, SurfaceStub, get_field, update_field!
+    update_field!, AtmosModelSimulation, SurfaceModelSimulation, SurfaceStub, get_field, update_field!, step!, reinit!
 import ClimaCoupler.FluxCalculator: CombinedStateFluxes, PartitionedStateFluxes, calculate_surface_air_density
 import ClimaCoupler.FieldExchanger:
-    import_atmos_fields!,
-    import_combined_surface_fields!,
-    update_model_sims!,
-    reinit_model_sims!,
-    reinit!,
-    step_model_sims!,
-    step!
+    import_atmos_fields!, import_combined_surface_fields!, update_model_sims!, reinit_model_sims!, step_model_sims!
+
 
 
 # test for a simple generic atmos model
@@ -60,6 +55,8 @@ get_field(sim::Union{TestSurfaceSimulation1, TestSurfaceSimulation2}, ::Val{:sur
 get_field(sim::Union{TestSurfaceSimulation2, TestSurfaceSimulation2}, ::Val{:surface_humidity}) =
     sim.cache_field .* eltype(sim.cache_field)(0)
 
+reinit!(::TestSurfaceSimulation1) = nothing
+step!(::TestSurfaceSimulation1, _) = nothing
 
 # atmos sim
 struct TestAtmosSimulation{C} <: AtmosModelSimulation
@@ -239,10 +236,10 @@ for FT in (Float32, Float64)
         end
     end
     @testset "reinit_model_sims! for FT=$FT" begin
-        @test reinit_model_sims!((; stub = SurfaceStub(FT(0)))) == nothing
+        @test reinit_model_sims!((; stub = TestSurfaceSimulation1(FT(0)))) == nothing
     end
 
     @testset "step_model_sims! for FT=$FT" begin
-        @test step_model_sims!((; stub = SurfaceStub(FT(0))), 1) == nothing
+        @test step_model_sims!((; stub = TestSurfaceSimulation1(FT(0))), 1) == nothing
     end
 end
diff --git a/test/flux_calculator_tests.jl b/test/flux_calculator_tests.jl
index 078f9c095..06ba59fea 100644
--- a/test/flux_calculator_tests.jl
+++ b/test/flux_calculator_tests.jl
@@ -301,15 +301,13 @@ for FT in (Float32, Float64)
     end
 
     @testset "update_turbulent_fluxes_point! for FT=$FT" begin
-        sim = Interfacer.SurfaceStub([])
-        sim2 = DummySurfaceSimulation3([], [], [], [])
+        sim = DummySurfaceSimulation3([], [], [], [])
         colidx = Fields.ColumnIndex{2}((1, 1), 73) # arbitrary index
-        @test update_turbulent_fluxes_point!(sim, (;), colidx) == nothing
         @test_throws ErrorException(
             "update_turbulent_fluxes_point! is required to be dispatched on" *
-            Interfacer.name(sim2) *
+            Interfacer.name(sim) *
             ", but no method defined",
-        ) update_turbulent_fluxes_point!(sim2, (;), colidx) == ErrorException
+        ) update_turbulent_fluxes_point!(sim, (;), colidx) == ErrorException
     end
 
     @testset "surface_thermo_state for FT=$FT" begin
diff --git a/test/interfacer_tests.jl b/test/interfacer_tests.jl
index ef09cfdc4..5d54c27e6 100644
--- a/test/interfacer_tests.jl
+++ b/test/interfacer_tests.jl
@@ -15,7 +15,10 @@ import ClimaCoupler.Interfacer:
     SeaIceModelSimulation,
     AtmosModelSimulation,
     SurfaceStub,
-    update_field!
+    update_field!,
+    reinit!,
+    step!,
+    update_turbulent_fluxes_point!
 
 # test for a simple generic surface model
 struct DummySimulation{S} <: SeaIceModelSimulation
@@ -231,6 +234,34 @@ end
     end
 end
 
+@testset "undefined step! error" begin
+    FT = Float32
+    sim = DummySimulation3(nothing)
+    @test_throws ErrorException("undefined step! for " * name(sim)) step!(sim, 1)
+end
+
+@testset "undefined reinit! error" begin
+    FT = Float32
+    sim = DummySimulation3(nothing)
+    @test_throws ErrorException("undefined reinit! for " * name(sim)) reinit!(sim)
+end
+
+@testset "SurfaceStub step!" begin
+    FT = Float32
+    @test step!(SurfaceStub(FT(0)), 1) == nothing
+end
+
+@testset "SurfaceStub reinit!" begin
+    FT = Float32
+    @test reinit!(SurfaceStub(FT(0))) == nothing
+end
+
+@testset "SurfaceStub update_turbulent_fluxes_point!" begin
+    FT = Float32
+    colidx = Fields.ColumnIndex{2}((1, 1), 73) # arbitrary index
+    @test update_turbulent_fluxes_point!(SurfaceStub(FT(0)), (;), colidx) == nothing
+end
+
 # # Test that update_field! gives correct warnings for unextended fields
 # for value in (
 #     :air_density,