diff --git a/src/abstractsparsearrayinterface.jl b/src/abstractsparsearrayinterface.jl
index c471ea2..aa64d9f 100644
--- a/src/abstractsparsearrayinterface.jl
+++ b/src/abstractsparsearrayinterface.jl
@@ -1,25 +1,30 @@
 # Minimal interface for `SparseArrayInterface`.
-# TODO: Define default definitions for these based
-# on the dense case.
-# TODO: Define as `MethodError`.
-## isstored(a::AbstractArray, I::Int...) = true
-isstored(a::AbstractArray, I::Int...) = error("Not implemented.")
-## eachstoredindex(a::AbstractArray) = eachindex(a)
-eachstoredindex(a::AbstractArray) = error("Not implemented.")
-## getstoredindex(a::AbstractArray, I::Int...) = getindex(a, I...)
-getstoredindex(a::AbstractArray, I::Int...) = error("Not implemented.")
-## setstoredindex!(a::AbstractArray, value, I::Int...) = setindex!(a, value, I...)
-setstoredindex!(a::AbstractArray, value, I::Int...) = error("Not implemented.")
-## setunstoredindex!(a::AbstractArray, value, I::Int...) = setindex!(a, value, I...)
-setunstoredindex!(a::AbstractArray, value, I::Int...) = error("Not implemented.")
+isstored(a::AbstractArray, I::Int...) = true
+eachstoredindex(a::AbstractArray) = eachindex(a)
+getstoredindex(a::AbstractArray, I::Int...) = getindex(a, I...)
+function setstoredindex!(a::AbstractArray, value, I::Int...)
+  setindex!(a, value, I...)
+  return a
+end
+# TODO: Should this error by default if the value at the index
+# is stored? It could be disabled with something analogous
+# to `checkbounds`, like `checkstored`/`checkunstored`.
+function setunstoredindex!(a::AbstractArray, value, I::Int...)
+  setindex!(a, value, I...)
+  return a
+end
 
 # TODO: Use `Base.to_indices`?
 isstored(a::AbstractArray, I::CartesianIndex) = isstored(a, Tuple(I)...)
+# TODO: Use `Base.to_indices`?
 getstoredindex(a::AbstractArray, I::CartesianIndex) = getstoredindex(a, Tuple(I)...)
+# TODO: Use `Base.to_indices`?
 getunstoredindex(a::AbstractArray, I::CartesianIndex) = getunstoredindex(a, Tuple(I)...)
+# TODO: Use `Base.to_indices`?
 function setstoredindex!(a::AbstractArray, value, I::CartesianIndex)
   return setstoredindex!(a, value, Tuple(I)...)
 end
+# TODO: Use `Base.to_indices`?
 function setunstoredindex!(a::AbstractArray, value, I::CartesianIndex)
   return setunstoredindex!(a, value, Tuple(I)...)
 end
@@ -33,6 +38,9 @@ getunstoredindex(a::AbstractArray, I::Int...) = zero(eltype(a))
 storedlength(a::AbstractArray) = length(storedvalues(a))
 storedpairs(a::AbstractArray) = map(I -> I => getstoredindex(a, I), eachstoredindex(a))
 
+to_vec(x) = vec(collect(x))
+to_vec(x::AbstractArray) = vec(x)
+
 # A view of the stored values of an array.
 # Similar to: `@view a[collect(eachstoredindex(a))]`, but the issue
 # with that is it returns a `SubArray` wrapping a sparse array, which
@@ -47,7 +55,7 @@ struct StoredValues{T,A<:AbstractArray{T},I} <: AbstractVector{T}
   array::A
   storedindices::I
 end
-StoredValues(a::AbstractArray) = StoredValues(a, collect(eachstoredindex(a)))
+StoredValues(a::AbstractArray) = StoredValues(a, to_vec(eachstoredindex(a)))
 Base.size(a::StoredValues) = size(a.storedindices)
 Base.getindex(a::StoredValues, I::Int) = getstoredindex(a.array, a.storedindices[I])
 function Base.setindex!(a::StoredValues, value, I::Int)
diff --git a/test/Project.toml b/test/Project.toml
index 266d4f0..9a08f31 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,7 +1,9 @@
 [deps]
+Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 Derive = "a07dfc7f-7d04-4eb5-84cc-a97f051f655a"
 Dictionaries = "85a47980-9c8c-11e8-2b9f-f7ca1fa99fb4"
+JLArrays = "27aeb0d3-9eb9-45fb-866b-73c2ecf80fcb"
 SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
 Suppressor = "fd094767-a336-5f1f-9728-57cf17d0bbfb"
diff --git a/test/basics/test_basics.jl b/test/basics/test_basics.jl
index 0970a6b..c8764c6 100644
--- a/test/basics/test_basics.jl
+++ b/test/basics/test_basics.jl
@@ -1,6 +1,63 @@
-using SparseArraysBase: SparseArraysBase
+using Adapt: adapt
+using JLArrays: JLArray, @allowscalar
+using SparseArraysBase:
+  SparseArraysBase,
+  eachstoredindex,
+  getstoredindex,
+  getunstoredindex,
+  isstored,
+  setstoredindex!,
+  setunstoredindex!,
+  storedlength,
+  storedpairs,
+  storedvalues
 using Test: @test, @testset
 
-@testset "SparseArraysBase" begin
-  # Tests go here.
+elts = (Float32, Float64, Complex{Float32}, Complex{Float64})
+arrayts = (Array, JLArray)
+@testset "SparseArraysBase (arraytype=$arrayt, eltype=$elt)" for arrayt in arrayts,
+  elt in elts
+
+  dev(x) = adapt(arrayt, x)
+
+  n = 2
+  a = dev(randn(elt, n, n))
+  @test storedlength(a) == length(a)
+  for indexstyle in (IndexLinear(), IndexCartesian())
+    for I in eachindex(indexstyle, a)
+      @test isstored(a, I)
+    end
+  end
+  @test eachstoredindex(a) == eachindex(a)
+  # TODO: We should be specializing these for dense/strided arrays,
+  # probably we can have a trait for that. It could be based
+  # on the `ArrayLayouts.MemoryLayout`.
+  @allowscalar @test storedvalues(a) == vec(a)
+  @allowscalar @test storedpairs(a) == collect(pairs(vec(a)))
+  @allowscalar for I in eachindex(a)
+    @test getstoredindex(a, I) == a[I]
+    @test iszero(getunstoredindex(a, I))
+  end
+  @allowscalar for I in eachindex(IndexCartesian(), a)
+    @test getstoredindex(a, I) == a[I]
+    @test iszero(getunstoredindex(a, I))
+  end
+
+  a = dev(randn(elt, n, n))
+  for I in ((1, 2), (CartesianIndex(1, 2),))
+    b = copy(a)
+    value = randn(elt)
+    @allowscalar setstoredindex!(b, value, I...)
+    @allowscalar b[I...] == value
+  end
+
+  # TODO: Should `setunstoredindex!` error by default
+  # if the value at that index is already stored?
+  a = dev(randn(elt, n, n))
+  for I in ((1, 2), (CartesianIndex(1, 2),))
+    b = copy(a)
+    value = randn(elt)
+    @allowscalar setunstoredindex!(b, value, I...)
+    @allowscalar b[I...] == value
+  end
 end