diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
deleted file mode 100644
index 8d6ffc1..0000000
--- a/.github/workflows/CI.yml
+++ /dev/null
@@ -1,79 +0,0 @@
-name: CI
-on:
-  push:
-    branches:
-      - main
-    tags: ['*']
-  pull_request:
-  workflow_dispatch:
-concurrency:
-  # Skip intermediate builds: always.
-  # Cancel intermediate builds: only if it is a pull request build.
-  group: ${{ github.workflow }}-${{ github.ref }}
-  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
-jobs:
-  test:
-    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }}
-    runs-on: ${{ matrix.os }}
-    timeout-minutes: 60
-    permissions: # needed to allow julia-actions/cache to proactively delete old caches that it has created
-      actions: write
-      contents: read
-    strategy:
-      fail-fast: false
-      matrix:
-        version:
-          # - 'lts' # TODO: Reenable once dependencies are registered.
-          - '1'
-        os:
-          - ubuntu-latest
-          - macOS-latest
-          - windows-latest
-        arch:
-          - x64
-    steps:
-      - uses: actions/checkout@v4
-      - uses: julia-actions/setup-julia@v2
-        with:
-          version: ${{ matrix.version }}
-          arch: ${{ matrix.arch }}
-      - uses: julia-actions/cache@v2
-      - uses: julia-actions/julia-buildpkg@v1
-      - uses: julia-actions/julia-runtest@v1
-      - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v5
-        with:
-          files: lcov.info
-          token: ${{ secrets.CODECOV_TOKEN }}
-          fail_ci_if_error: false
-  docs:
-    name: Documentation
-    runs-on: ubuntu-latest
-    permissions:
-      actions: write # needed to allow julia-actions/cache to proactively delete old caches that it has created
-      contents: write
-      statuses: write
-    steps:
-      - uses: actions/checkout@v4
-      - uses: julia-actions/setup-julia@v2
-        with:
-          version: '1'
-      - uses: julia-actions/cache@v2
-      - name: Configure doc environment
-        shell: julia --project=docs --color=yes {0}
-        run: |
-          using Pkg
-          Pkg.develop(PackageSpec(path=pwd()))
-          Pkg.instantiate()
-      - uses: julia-actions/julia-buildpkg@v1
-      - uses: julia-actions/julia-docdeploy@v1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}
-      - name: Run doctests
-        shell: julia --project=docs --color=yes {0}
-        run: |
-          using Documenter: DocMeta, doctest
-          using DiagonalArrays
-          DocMeta.setdocmeta!(DiagonalArrays, :DocTestSetup, :(using DiagonalArrays); recursive=true)
-          doctest(DiagonalArrays)
diff --git a/.github/workflows/Documentation.yml b/.github/workflows/Documentation.yml
new file mode 100644
index 0000000..01a7f7a
--- /dev/null
+++ b/.github/workflows/Documentation.yml
@@ -0,0 +1,23 @@
+name: "Documentation"
+
+on:
+  push:
+    branches:
+      - main
+    tags: '*'
+  pull_request:
+  schedule:
+    - cron: '1 4 * * 4'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref_name != github.event.repository.default_branch || github.ref != 'refs/tags/v*' }}
+
+jobs:
+  build-and-deploy-docs:
+    name: "Documentation"
+    uses: "ITensor/ITensorActions/.github/workflows/Documentation.yml@main"
+    with:
+      localregistry: https://github.com/ITensor/ITensorRegistry.git
+    secrets:
+      CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
diff --git a/.github/workflows/FormatCheck.yml b/.github/workflows/FormatCheck.yml
index bb6d933..3f78afc 100644
--- a/.github/workflows/FormatCheck.yml
+++ b/.github/workflows/FormatCheck.yml
@@ -1,35 +1,13 @@
-name: Format check
+name: "Format Check"
+
 on:
   push:
-    branches: [main]
-    tags: [v*]
+    branches:
+      - 'main'
+    tags: '*'
   pull_request:
 
 jobs:
-  format:
+  format-check:
     name: "Format Check"
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: julia-actions/setup-julia@v2
-        with:
-          version: 1
-      - name: Install JuliaFormatter and format
-        run: |
-          julia  -e 'using Pkg; Pkg.add(PackageSpec(name="JuliaFormatter"))'
-          julia  -e 'using JuliaFormatter; format(".", verbose=true)'
-      - name: Check format
-        run: |
-          julia -e '
-          out = Cmd(`git diff --name-only`) |> read |> String
-          if out == ""
-              exit(0)
-          else
-              @error "The following files have not been formatted:"
-              write(stdout, out)
-              out_diff = Cmd(`git diff`) |> read |> String
-              @error "Diff:"
-              write(stdout, out_diff)
-              exit(1)
-              @error ""
-          end'
+    uses: "ITensor/ITensorActions/.github/workflows/FormatCheck.yml@main"
diff --git a/.github/workflows/LiterateCheck.yml b/.github/workflows/LiterateCheck.yml
index 15a72c3..2ca5f27 100644
--- a/.github/workflows/LiterateCheck.yml
+++ b/.github/workflows/LiterateCheck.yml
@@ -1,44 +1,15 @@
-name: Literate check
+name: "Literate Check"
+
 on:
   push:
-    branches: [main]
-    tags: [v*]
+    branches:
+      - 'main'
+    tags: '*'
   pull_request:
 
 jobs:
   literate:
     name: "Literate Check"
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: julia-actions/setup-julia@v2
-        with:
-          version: 1
-      - name: Install Literate and generate docs
-        run: |
-          julia  -e '
-          using Pkg
-          # TODO: Delete once they are registered.
-          Pkg.add(url="https://github.com/ITensor/BroadcastMapConversion.jl")
-          Pkg.add(url="https://github.com/ITensor/NestedPermutedDimsArrays.jl")
-          Pkg.add(url="https://github.com/ITensor/TypeParameterAccessors.jl")
-          Pkg.add(url="https://github.com/ITensor/SparseArraysBase.jl")
-          Pkg.develop(PackageSpec(path=pwd()))
-          Pkg.instantiate()
-          Pkg.add(PackageSpec(name="Literate"))'
-          julia  -e 'include("docs/make_readme.jl")'
-      - name: Check if docs need to be updated
-        run: |
-          julia -e '
-          out = Cmd(`git diff --name-only`) |> read |> String
-          if out == ""
-              exit(0)
-          else
-              @error "The docs are outdated, rerun Literate to regenerate them."
-              write(stdout, out)
-              out_diff = Cmd(`git diff`) |> read |> String
-              @error "Diff:"
-              write(stdout, out_diff)
-              exit(1)
-              @error ""
-          end'
+    uses: "ITensor/ITensorActions/.github/workflows/LiterateCheck.yml@main"
+    with:
+      localregistry: https://github.com/ITensor/ITensorRegistry.git
diff --git a/.github/workflows/Tests.yml b/.github/workflows/Tests.yml
new file mode 100644
index 0000000..5a0a306
--- /dev/null
+++ b/.github/workflows/Tests.yml
@@ -0,0 +1,42 @@
+name: Tests
+on:
+  push:
+    branches:
+      - 'master'
+      - 'main'
+      - 'release-'
+    tags: '*'
+    paths-ignore:
+      - 'docs/**'
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  # Cancel intermediate builds: only if it is a pull request build.
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+
+jobs:
+  tests:
+    name: "Tests"
+    strategy:
+      fail-fast: false
+      matrix:
+        version:
+          - 'lts' # minimal supported version
+          - '1' # latest released Julia version
+        # group:
+        #   - 'core'
+        #   - 'optional'
+        os:
+          - ubuntu-latest
+          - macOS-latest
+          - windows-latest
+    uses: "ITensor/ITensorActions/.github/workflows/Tests.yml@main"
+    with:
+      group: "${{ matrix.group }}"
+      julia-version: "${{ matrix.version }}"
+      os: "${{ matrix.os }}"
+      localregistry: https://github.com/ITensor/ITensorRegistry.git
+    secrets:
+      CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index bff1fb7..6599365 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -7,7 +7,8 @@ repos:
   - id: check-yaml
   - id: end-of-file-fixer
     exclude_types: [markdown]  # incompatible with Literate.jl
-- repo: https://github.com/qiaojunfeng/pre-commit-julia-format
-  rev: v0.2.0
+
+- repo: "https://github.com/domluna/JuliaFormatter.jl"
+  rev: v1.0.62  
   hooks:
-  - id: julia-format
+  - id: "julia-formatter"
diff --git a/Project.toml b/Project.toml
index 9c86ffb..49d1b64 100644
--- a/Project.toml
+++ b/Project.toml
@@ -10,21 +10,10 @@ NestedPermutedDimsArrays = "2c2a8ec4-3cfc-4276-aa3e-1307b4294e58"
 SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
 TypeParameterAccessors = "7e5a90cf-f82e-492e-a09b-e3e26432c138"
 
-[sources]
-BroadcastMapConversion = {url = "https://github.com/ITensor/BroadcastMapConversion.jl"}
-NestedPermutedDimsArrays = {url = "https://github.com/ITensor/NestedPermutedDimsArrays.jl"}
-SparseArraysBase = {url = "https://github.com/ITensor/SparseArraysBase.jl"}
-TypeParameterAccessors = {url = "https://github.com/ITensor/TypeParameterAccessors.jl"}
-
 [compat]
-Aqua = "0.8.9"
 ArrayLayouts = "1.10.4"
-Test = "1.10"
+BroadcastMapConversion = "0.1"
+NestedPermutedDimsArrays = "0.1"
+SparseArraysBase = "0.1"
+TypeParameterAccessors = "0.1"
 julia = "1.10"
-
-[extras]
-Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
-Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
-
-[targets]
-test = ["Aqua", "Test"]
diff --git a/README.md b/README.md
index 62c9019..9161284 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 [![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](https://ITensor.github.io/DiagonalArrays.jl/stable/)
 [![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://ITensor.github.io/DiagonalArrays.jl/dev/)
-[![Build Status](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/CI.yml?query=branch%3Amain)
+[![Build Status](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/Tests.yml/badge.svg?branch=main)](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/Tests.yml?query=branch%3Amain)
 [![Coverage](https://codecov.io/gh/ITensor/DiagonalArrays.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/ITensor/DiagonalArrays.jl)
 [![Code Style: Blue](https://img.shields.io/badge/code%20style-blue-4495d1.svg)](https://github.com/invenia/BlueStyle)
 [![Aqua](https://raw.githubusercontent.com/JuliaTesting/Aqua.jl/master/badge.svg)](https://github.com/JuliaTesting/Aqua.jl)
@@ -11,20 +11,24 @@ A n-dimensional diagonal array type in Julia.
 
 ## Installation instructions
 
+This package resides in the `ITensor/ITensorRegistry` local registry.
+In order to install, simply add that registry through your package manager.
+This step is only required once.
 ```julia
 julia> using Pkg: Pkg
 
-julia> using Pkg: Pkg
-
-julia> Pkg.add(url="https://github.com/ITensor/BroadcastMapConversion.jl")
-
-julia> Pkg.add(url="https://github.com/ITensor/NestedPermutedDimsArrays.jl")
-
-julia> Pkg.add(url="https://github.com/ITensor/TypeParameterAccessors.jl")
+julia> Pkg.Registry.add(url="https://github.com/ITensor/ITensorRegistry")
+```
+or:
+```julia
+julia> Pkg.Registry.add(url="git@github.com:ITensor/ITensorRegistry.git")
+```
+if you want to use SSH credentials, which can make it so you don't have to enter your Github ursername and password when registering packages.
 
-julia> Pkg.add(url="https://github.com/ITensor/SparseArraysBase.jl")
+Then, the package can be added as usual through the package manager:
 
-julia> Pkg.add(url="https://github.com/ITensor/DiagonalArrays.jl")
+```julia
+julia> Pkg.add("DiagonalArrays")
 ```
 
 ## Examples
diff --git a/docs/Project.toml b/docs/Project.toml
index 74d3bea..35294a6 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -6,10 +6,3 @@ Literate = "98b081ad-f1c9-55d3-8b20-4c87d4299306"
 NestedPermutedDimsArrays = "2c2a8ec4-3cfc-4276-aa3e-1307b4294e58"
 SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
 TypeParameterAccessors = "7e5a90cf-f82e-492e-a09b-e3e26432c138"
-
-
-[sources]
-BroadcastMapConversion = {url = "https://github.com/ITensor/BroadcastMapConversion.jl"}
-NestedPermutedDimsArrays = {url = "https://github.com/ITensor/NestedPermutedDimsArrays.jl"}
-SparseArraysBase = {url = "https://github.com/ITensor/SparseArraysBase.jl"}
-TypeParameterAccessors = {url = "https://github.com/ITensor/TypeParameterAccessors.jl"}
diff --git a/examples/Project.toml b/examples/Project.toml
index 3df672f..01231f7 100644
--- a/examples/Project.toml
+++ b/examples/Project.toml
@@ -4,9 +4,3 @@ DiagonalArrays = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 NestedPermutedDimsArrays = "2c2a8ec4-3cfc-4276-aa3e-1307b4294e58"
 SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
 TypeParameterAccessors = "7e5a90cf-f82e-492e-a09b-e3e26432c138"
-
-[sources]
-BroadcastMapConversion = {url = "https://github.com/ITensor/BroadcastMapConversion.jl"}
-NestedPermutedDimsArrays = {url = "https://github.com/ITensor/NestedPermutedDimsArrays.jl"}
-SparseArraysBase = {url = "https://github.com/ITensor/SparseArraysBase.jl"}
-TypeParameterAccessors = {url = "https://github.com/ITensor/TypeParameterAccessors.jl"}
diff --git a/examples/README.jl b/examples/README.jl
index 5e54547..827d71a 100644
--- a/examples/README.jl
+++ b/examples/README.jl
@@ -2,7 +2,7 @@
 # 
 # [![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](https://ITensor.github.io/DiagonalArrays.jl/stable/)
 # [![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://ITensor.github.io/DiagonalArrays.jl/dev/)
-# [![Build Status](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/CI.yml?query=branch%3Amain)
+# [![Build Status](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/Tests.yml/badge.svg?branch=main)](https://github.com/ITensor/DiagonalArrays.jl/actions/workflows/Tests.yml?query=branch%3Amain)
 # [![Coverage](https://codecov.io/gh/ITensor/DiagonalArrays.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/ITensor/DiagonalArrays.jl)
 # [![Code Style: Blue](https://img.shields.io/badge/code%20style-blue-4495d1.svg)](https://github.com/invenia/BlueStyle)
 # [![Aqua](https://raw.githubusercontent.com/JuliaTesting/Aqua.jl/master/badge.svg)](https://github.com/JuliaTesting/Aqua.jl)
@@ -11,19 +11,29 @@
 
 # ## Installation instructions
 
+# This package resides in the `ITensor/ITensorRegistry` local registry.
+# In order to install, simply add that registry through your package manager.
+# This step is only required once.
 #=
 ```julia
 julia> using Pkg: Pkg
 
-julia> Pkg.add(url="https://github.com/ITensor/BroadcastMapConversion.jl")
-
-julia> Pkg.add(url="https://github.com/ITensor/NestedPermutedDimsArrays.jl")
-
-julia> Pkg.add(url="https://github.com/ITensor/TypeParameterAccessors.jl")
+julia> Pkg.Registry.add(url="https://github.com/ITensor/ITensorRegistry")
+```
+=#
+# or:
+#=
+```julia
+julia> Pkg.Registry.add(url="git@github.com:ITensor/ITensorRegistry.git")
+```
+=#
+# if you want to use SSH credentials, which can make it so you don't have to enter your Github ursername and password when registering packages.
 
-julia> Pkg.add(url="https://github.com/ITensor/SparseArraysBase.jl")
+# Then, the package can be added as usual through the package manager:
 
-julia> Pkg.add(url="https://github.com/ITensor/DiagonalArrays.jl")
+#=
+```julia
+julia> Pkg.add("DiagonalArrays")
 ```
 =#
 
diff --git a/test/Project.toml b/test/Project.toml
index b22f139..ab3f7c7 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,4 +1,13 @@
 [deps]
 DiagonalArrays = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 SparseArraysBase = "0d5efcca-f356-4864-8770-e1ed8d78f208"
+Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
+SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
+Suppressor = "fd094767-a336-5f1f-9728-57cf17d0bbfb"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+
+[compat]
+Aqua = "0.8.9"
+SafeTestsets = "0.1"
+Suppressor = "0.2"
+Test = "1.10"
diff --git a/test/runtests.jl b/test/runtests.jl
index 72a133e..bd97441 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,55 +1,61 @@
-@eval module $(gensym())
-using Test: @test, @testset, @test_broken
-using DiagonalArrays: DiagonalArrays, DiagonalArray, DiagonalMatrix, diaglength
-using SparseArraysBase: SparseArrayDOK, stored_length
-@testset "Test DiagonalArrays" begin
-  @testset "README" begin
-    @test include(joinpath(pkgdir(DiagonalArrays), "examples", "README.jl")) isa Any
-  end
-  @testset "DiagonalArray (eltype=$elt)" for elt in (
-    Float32, Float64, Complex{Float32}, Complex{Float64}
-  )
-    @testset "Basics" begin
-      a = fill(one(elt), 2, 3)
-      @test diaglength(a) == 2
-      a = fill(one(elt))
-      @test diaglength(a) == 1
+using SafeTestsets: @safetestset
+using Suppressor: Suppressor
+
+# check for filtered groups
+# either via `--group=ALL` or through ENV["GROUP"]
+const pat = r"(?:--group=)(\w+)"
+arg_id = findfirst(contains(pat), ARGS)
+const GROUP = uppercase(
+  if isnothing(arg_id)
+    get(ENV, "GROUP", "ALL")
+  else
+    only(match(pat, ARGS[arg_id]).captures)
+  end,
+)
+
+"match files of the form `test_*.jl`, but exclude `*setup*.jl`"
+istestfile(fn) =
+  endswith(fn, ".jl") && startswith(basename(fn), "test_") && !contains(fn, "setup")
+"match files of the form `*.jl`, but exclude `*_notest.jl` and `*setup*.jl`"
+isexamplefile(fn) =
+  endswith(fn, ".jl") && !endswith(fn, "_notest.jl") && !contains(fn, "setup")
+
+@time begin
+  # tests in groups based on folder structure
+  for testgroup in filter(isdir, readdir(@__DIR__))
+    if GROUP == "ALL" || GROUP == uppercase(testgroup)
+      for file in filter(istestfile, readdir(joinpath(@__DIR__, testgroup); join=true))
+        @eval @safetestset $file begin
+          include($file)
+        end
+      end
     end
-    @testset "Matrix multiplication" begin
-      a1 = DiagonalArray{elt}(undef, (2, 3))
-      a1[1, 1] = 11
-      a1[2, 2] = 22
-      a2 = DiagonalArray{elt}(undef, (3, 4))
-      a2[1, 1] = 11
-      a2[2, 2] = 22
-      a2[3, 3] = 33
-      a_dest = a1 * a2
-      # TODO: Use `densearray` to make generic to GPU.
-      @test Array(a_dest) ≈ Array(a1) * Array(a2)
-      # TODO: Make this work with `ArrayLayouts`.
-      @test stored_length(a_dest) == 2
-      @test a_dest isa DiagonalMatrix{elt}
+  end
 
-      # TODO: Make generic to GPU, use `allocate_randn`?
-      a2 = randn(elt, (3, 4))
-      a_dest = a1 * a2
-      # TODO: Use `densearray` to make generic to GPU.
-      @test Array(a_dest) ≈ Array(a1) * Array(a2)
-      @test stored_length(a_dest) == 8
-      @test a_dest isa Matrix{elt}
+  # single files in top folder
+  for file in filter(istestfile, readdir(@__DIR__))
+    (file == basename(@__FILE__)) && continue # exclude this file to avoid infinite recursion
+    @eval @safetestset $file begin
+      include($file)
+    end
+  end
 
-      a2 = SparseArrayDOK{elt}(3, 4)
-      a2[1, 1] = 11
-      a2[2, 2] = 22
-      a2[3, 3] = 33
-      a_dest = a1 * a2
-      # TODO: Use `densearray` to make generic to GPU.
-      @test Array(a_dest) ≈ Array(a1) * Array(a2)
-      # TODO: Define `SparseMatrixDOK`.
-      # TODO: Make this work with `ArrayLayouts`.
-      @test stored_length(a_dest) == 2
-      @test a_dest isa SparseArrayDOK{elt,2}
+  # test examples
+  examplepath = joinpath(@__DIR__, "..", "examples")
+  for (root, _, files) in walkdir(examplepath)
+    contains(chopprefix(root, @__DIR__), "setup") && continue
+    for file in filter(isexamplefile, files)
+      filename = joinpath(root, file)
+      @eval begin
+        @safetestset $file begin
+          $(Expr(
+            :macrocall,
+            GlobalRef(Suppressor, Symbol("@suppress")),
+            LineNumberNode(@__LINE__, @__FILE__),
+            :(include($filename)),
+          ))
+        end
+      end
     end
   end
 end
-end
diff --git a/test/test_aqua.jl b/test/test_aqua.jl
new file mode 100644
index 0000000..15334c6
--- /dev/null
+++ b/test/test_aqua.jl
@@ -0,0 +1,8 @@
+using DiagonalArrays: DiagonalArrays
+using Aqua: Aqua
+using Test: @testset
+
+@testset "Code quality (Aqua.jl)" begin
+  # TODO: fix ambiguities
+  Aqua.test_all(DiagonalArrays; ambiguities=false)
+end
diff --git a/test/test_basics.jl b/test/test_basics.jl
new file mode 100644
index 0000000..0da000b
--- /dev/null
+++ b/test/test_basics.jl
@@ -0,0 +1,50 @@
+using Test: @test, @testset, @test_broken
+using DiagonalArrays: DiagonalArrays, DiagonalArray, DiagonalMatrix, diaglength
+using SparseArraysBase: SparseArrayDOK, stored_length
+@testset "Test DiagonalArrays" begin
+  @testset "DiagonalArray (eltype=$elt)" for elt in (
+    Float32, Float64, Complex{Float32}, Complex{Float64}
+  )
+    @testset "Basics" begin
+      a = fill(one(elt), 2, 3)
+      @test diaglength(a) == 2
+      a = fill(one(elt))
+      @test diaglength(a) == 1
+    end
+    @testset "Matrix multiplication" begin
+      a1 = DiagonalArray{elt}(undef, (2, 3))
+      a1[1, 1] = 11
+      a1[2, 2] = 22
+      a2 = DiagonalArray{elt}(undef, (3, 4))
+      a2[1, 1] = 11
+      a2[2, 2] = 22
+      a2[3, 3] = 33
+      a_dest = a1 * a2
+      # TODO: Use `densearray` to make generic to GPU.
+      @test Array(a_dest) ≈ Array(a1) * Array(a2)
+      # TODO: Make this work with `ArrayLayouts`.
+      @test stored_length(a_dest) == 2
+      @test a_dest isa DiagonalMatrix{elt}
+
+      # TODO: Make generic to GPU, use `allocate_randn`?
+      a2 = randn(elt, (3, 4))
+      a_dest = a1 * a2
+      # TODO: Use `densearray` to make generic to GPU.
+      @test Array(a_dest) ≈ Array(a1) * Array(a2)
+      @test stored_length(a_dest) == 8
+      @test a_dest isa Matrix{elt}
+
+      a2 = SparseArrayDOK{elt}(3, 4)
+      a2[1, 1] = 11
+      a2[2, 2] = 22
+      a2[3, 3] = 33
+      a_dest = a1 * a2
+      # TODO: Use `densearray` to make generic to GPU.
+      @test Array(a_dest) ≈ Array(a1) * Array(a2)
+      # TODO: Define `SparseMatrixDOK`.
+      # TODO: Make this work with `ArrayLayouts`.
+      @test stored_length(a_dest) == 2
+      @test a_dest isa SparseArrayDOK{elt,2}
+    end
+  end
+end