diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
new file mode 100644
index 0000000..a3e2149
--- /dev/null
+++ b/.git-blame-ignore-revs
@@ -0,0 +1 @@
+1f423a22d8b27926da7d7b7393c833da0f3714a4
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 76c0f80..ea72cdd 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -6,9 +6,17 @@ updates:
       interval: "monthly"
     labels:
       - "type: Maintenance"
+    groups:
+      actions:
+        patterns:
+          - "*"
   - package-ecosystem: "pip"
     directory: "/"
     schedule:
       interval: "monthly"
     labels:
       - "type: Maintenance"
+    groups:
+      actions:
+        patterns:
+          - "*"
diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index ca30553..e095b5c 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -21,7 +21,7 @@ jobs:
 
       - name: Install packages
         run: |
-          python -m pip install --upgrade pip wheel setuptools
+          python -m pip install --upgrade pip wheel setuptools spin
           python -m pip install ".[test]"
           python -m pip install --upgrade numpy
           python -m pip uninstall --yes scipy
@@ -29,11 +29,11 @@ jobs:
 
       - name: Measure test coverage
         run: |
-          python -m pytest --cov=lazy_loader --durations=10
+          spin test -c -- --durations=10
           # Tests fail if using `--doctest-modules`. I.e.,
-          # python -m pytest --cov=lazy_loader --doctest-modules --durations=20
+          # spin test -- --doctest-modules
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v5
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
diff --git a/.github/workflows/label-check.yaml b/.github/workflows/label-check.yaml
index a0e2e5c..d6e97f2 100644
--- a/.github/workflows/label-check.yaml
+++ b/.github/workflows/label-check.yaml
@@ -4,8 +4,10 @@ on:
   pull_request:
     types:
       - opened
+      - reopened
       - labeled
       - unlabeled
+      - synchronize
 
 env:
   LABELS: ${{ join( github.event.pull_request.labels.*.name, ' ' ) }}
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
deleted file mode 100644
index b2d6384..0000000
--- a/.github/workflows/lint.yml
+++ /dev/null
@@ -1,27 +0,0 @@
-name: lint
-
-on: [push, pull_request]
-
-jobs:
-  default:
-    runs-on: ${{ matrix.os }}-latest
-    strategy:
-      matrix:
-        os: [ubuntu]
-        python-version: ["3.10"]
-
-    steps:
-      - uses: actions/checkout@v4
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-          cache: "pip"
-
-      - name: Install dependencies
-        run: |
-          python -m pip install --upgrade pip
-          python -m pip install ".[lint]"
-
-      - name: Lint
-        run: pre-commit run --all-files --show-diff-on-failure --color always
diff --git a/.github/workflows/milestone-merged-prs.yaml b/.github/workflows/milestone-merged-prs.yaml
index 71ae037..f455839 100644
--- a/.github/workflows/milestone-merged-prs.yaml
+++ b/.github/workflows/milestone-merged-prs.yaml
@@ -12,7 +12,7 @@ jobs:
     name: attach to PR
     runs-on: ubuntu-latest
     steps:
-      - uses: scientific-python/attach-next-milestone-action@bc07be829f693829263e57d5e8489f4e57d3d420
+      - uses: scientific-python/attach-next-milestone-action@c9cfab10ad0c67fed91b01103db26b7f16634639
         with:
           token: ${{ secrets.MILESTONE_LABELER_TOKEN }}
           force: true
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index c454680..6cf247b 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -26,8 +26,8 @@ jobs:
       - name: Build wheels
         run: |
           git clean -fxd
-          pip install -U build twine wheel
-          python -m build --sdist --wheel
+          pip install -U build twine wheel spin
+          spin sdist -- --wheel
 
       - name: Publish package distributions to PyPI
         uses: pypa/gh-action-pypi-publish@release/v1
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index af6fc19..a299fe7 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,6 +1,10 @@
 name: test
 
-on: [push, pull_request]
+on: [workflow_dispatch, push, pull_request]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 jobs:
   default:
@@ -9,16 +13,7 @@ jobs:
       matrix:
         os: [ubuntu, macos, windows]
         python-version:
-          [
-            "3.7",
-            "3.8",
-            "3.9",
-            "3.10",
-            "3.11",
-            "3.12-dev",
-            "pypy-3.8",
-            "pypy-3.9",
-          ]
+          ["3.9", "3.10", "3.11", "3.12", "3.13", "pypy-3.9", "pypy-3.10"]
 
     steps:
       - uses: actions/checkout@v4
@@ -30,9 +25,9 @@ jobs:
 
       - name: Install dependencies
         run: |
-          python -m pip install --upgrade pip
+          python -m pip install --upgrade pip spin
           python -m pip install ".[test]"
 
       - name: Test
         run: |
-          python -m pytest
+          spin test
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 0484b49..5a6b373 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,9 +1,15 @@
 # Install pre-commit hooks via
 # pre-commit install
 
+ci:
+  autofix_prs: false
+  autofix_commit_msg: |
+    '[pre-commit.ci 🤖] Apply code format tools to PR'
+  autoupdate_schedule: quarterly
+
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: c4a0b883114b00d8d76b479c820ce7950211c99b # frozen: v4.5.0
+    rev: cef0300fd0fc4d2a87a85fa2093c6b283ea36f4b # frozen: v5.0.0
     hooks:
       - id: trailing-whitespace
       - id: end-of-file-fixer
@@ -16,20 +22,21 @@ repos:
       - id: check-toml
       - id: check-added-large-files
 
-  - repo: https://github.com/pre-commit/mirrors-prettier
-    rev: ffb6a759a979008c0e6dff86e39f4745a2d9eac4 # frozen: v3.1.0
+  - repo: https://github.com/rbubley/mirrors-prettier
+    rev: 787fb9f542b140ba0b2aced38e6a3e68021647a3 # frozen: v3.5.3
     hooks:
       - id: prettier
         files: \.(html|md|yml|yaml|toml)
         args: [--prose-wrap=preserve]
 
-  - repo: https://github.com/psf/black
-    rev: 552baf822992936134cbd31a38f69c8cfe7c0f05 # frozen: 24.3.0
-    hooks:
-      - id: black
-
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: 0ccbb5b7942d83fbcf7cb5e0fd99633efd2351d7 # frozen: v0.3.5
+    rev: 971923581912ef60a6b70dbf0c3e9a39563c9d47 # frozen: v0.11.4
     hooks:
       - id: ruff
-        args: [--fix, --exit-non-zero-on-fix]
+        args: ["--fix", "--show-fixes", "--exit-non-zero-on-fix"]
+      - id: ruff-format
+
+  - repo: https://github.com/codespell-project/codespell
+    rev: "63c8f8312b7559622c0d82815639671ae42132ac" # frozen: v2.4.1
+    hooks:
+      - id: codespell
diff --git a/.spin/cmds.py b/.spin/cmds.py
new file mode 100644
index 0000000..7db4b98
--- /dev/null
+++ b/.spin/cmds.py
@@ -0,0 +1,35 @@
+import importlib
+import sys
+import textwrap
+
+import click
+from spin.cmds.util import run
+
+
+@click.command()
+@click.argument("pytest_args", nargs=-1)
+@click.option(
+    "-c",
+    "--coverage",
+    is_flag=True,
+    help="Generate a coverage report of executed tests.",
+)
+def test(pytest_args, coverage=False):
+    """🔧 Run tests"""
+    if not importlib.util.find_spec("lazy_loader"):
+        click.secho(
+            textwrap.dedent("""\
+              ERROR: The package is not installed.
+
+              Please do an editable install:
+
+                pip install -e .[test]
+
+              prior to running the tests."""),
+            fg="red",
+        )
+        sys.exit(1)
+
+    if coverage:
+        pytest_args = ("--cov=lazy_loader", *pytest_args)
+    run([sys.executable, "-m", "pytest", *list(pytest_args)])
diff --git a/CHANGELOG.md b/CHANGELOG.md
index acba09a..70b9d2f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,49 +1,49 @@
-# lazy_loader 0.4
+# lazy-loader 0.4
 
-We're happy to announce the release of lazy_loader 0.4!
+We're happy to announce the release of lazy-loader 0.4!
 
 ## Enhancements
 
-- ENH: Add require argument to load() to accept version specifiers ([#48](https://github.com/scientific-python/lazy_loader/pull/48)).
-- Add version as __version__ ([#97](https://github.com/scientific-python/lazy_loader/pull/97)).
+- ENH: Add require argument to load() to accept version specifiers ([#48](https://github.com/scientific-python/lazy-loader/pull/48)).
+- Add version as **version** ([#97](https://github.com/scientific-python/lazy-loader/pull/97)).
 
 ## Bug Fixes
 
-- Avoid exception when __frame_data["code_context"] is None ([#83](https://github.com/scientific-python/lazy_loader/pull/83)).
-- Make `lazy_load.load` partially thread-safe ([#90](https://github.com/scientific-python/lazy_loader/pull/90)).
+- Avoid exception when \_\_frame_data["code_context"] is None ([#83](https://github.com/scientific-python/lazy-loader/pull/83)).
+- Make `lazy_load.load` partially thread-safe ([#90](https://github.com/scientific-python/lazy-loader/pull/90)).
 
 ## Documentation
 
-- Add security contact ([#91](https://github.com/scientific-python/lazy_loader/pull/91)).
-- Recommend newer Python versions to avoid race ([#102](https://github.com/scientific-python/lazy_loader/pull/102)).
+- Add security contact ([#91](https://github.com/scientific-python/lazy-loader/pull/91)).
+- Recommend newer Python versions to avoid race ([#102](https://github.com/scientific-python/lazy-loader/pull/102)).
 
 ## Maintenance
 
-- Use label-check and attach-next-milestone-action ([#64](https://github.com/scientific-python/lazy_loader/pull/64)).
-- Use setuptools ([#65](https://github.com/scientific-python/lazy_loader/pull/65)).
-- Specify what goes in sdist ([#66](https://github.com/scientific-python/lazy_loader/pull/66)).
-- Use changelist ([#67](https://github.com/scientific-python/lazy_loader/pull/67)).
-- Used dependabot ([#68](https://github.com/scientific-python/lazy_loader/pull/68)).
-- Bump pre-commit from 3.3 to 3.3.3 ([#69](https://github.com/scientific-python/lazy_loader/pull/69)).
-- Bump scientific-python/attach-next-milestone-action from f94a5235518d4d34911c41e19d780b8e79d42238 to a4889cfde7d2578c1bc7400480d93910d2dd34f6 ([#72](https://github.com/scientific-python/lazy_loader/pull/72)).
-- Bump scientific-python/attach-next-milestone-action from a4889cfde7d2578c1bc7400480d93910d2dd34f6 to bc07be829f693829263e57d5e8489f4e57d3d420 ([#74](https://github.com/scientific-python/lazy_loader/pull/74)).
-- Bump actions/checkout from 3 to 4 ([#75](https://github.com/scientific-python/lazy_loader/pull/75)).
-- Bump changelist from 0.1 to 0.3 ([#77](https://github.com/scientific-python/lazy_loader/pull/77)).
-- Bump pre-commit from 3.3.3 to 3.4.0 ([#76](https://github.com/scientific-python/lazy_loader/pull/76)).
-- Use trusted publisher ([#78](https://github.com/scientific-python/lazy_loader/pull/78)).
-- Bump pre-commit from 3.4.0 to 3.5.0 ([#80](https://github.com/scientific-python/lazy_loader/pull/80)).
-- Bump changelist from 0.3 to 0.4 ([#81](https://github.com/scientific-python/lazy_loader/pull/81)).
-- Bump actions/checkout from 3 to 4 ([#82](https://github.com/scientific-python/lazy_loader/pull/82)).
-- Bump actions/setup-python from 4 to 5 ([#85](https://github.com/scientific-python/lazy_loader/pull/85)).
-- Bump pre-commit from 3.5.0 to 3.6.0 ([#84](https://github.com/scientific-python/lazy_loader/pull/84)).
-- Update pre-commit ([#87](https://github.com/scientific-python/lazy_loader/pull/87)).
-- Use setup-python pip cache ([#95](https://github.com/scientific-python/lazy_loader/pull/95)).
-- Bump codecov/codecov-action from 3 to 4 ([#93](https://github.com/scientific-python/lazy_loader/pull/93)).
-- Bump pre-commit from 3.6.0 to 3.6.2 ([#100](https://github.com/scientific-python/lazy_loader/pull/100)).
-- Bump changelist from 0.4 to 0.5 ([#99](https://github.com/scientific-python/lazy_loader/pull/99)).
-- Refuse star imports in stub loader ([#101](https://github.com/scientific-python/lazy_loader/pull/101)).
-- Bump pre-commit from 3.6.2 to 3.7.0 ([#103](https://github.com/scientific-python/lazy_loader/pull/103)).
-- Update pre-commit repos ([#104](https://github.com/scientific-python/lazy_loader/pull/104)).
+- Use label-check and attach-next-milestone-action ([#64](https://github.com/scientific-python/lazy-loader/pull/64)).
+- Use setuptools ([#65](https://github.com/scientific-python/lazy-loader/pull/65)).
+- Specify what goes in sdist ([#66](https://github.com/scientific-python/lazy-loader/pull/66)).
+- Use changelist ([#67](https://github.com/scientific-python/lazy-loader/pull/67)).
+- Used dependabot ([#68](https://github.com/scientific-python/lazy-loader/pull/68)).
+- Bump pre-commit from 3.3 to 3.3.3 ([#69](https://github.com/scientific-python/lazy-loader/pull/69)).
+- Bump scientific-python/attach-next-milestone-action from f94a5235518d4d34911c41e19d780b8e79d42238 to a4889cfde7d2578c1bc7400480d93910d2dd34f6 ([#72](https://github.com/scientific-python/lazy-loader/pull/72)).
+- Bump scientific-python/attach-next-milestone-action from a4889cfde7d2578c1bc7400480d93910d2dd34f6 to bc07be829f693829263e57d5e8489f4e57d3d420 ([#74](https://github.com/scientific-python/lazy-loader/pull/74)).
+- Bump actions/checkout from 3 to 4 ([#75](https://github.com/scientific-python/lazy-loader/pull/75)).
+- Bump changelist from 0.1 to 0.3 ([#77](https://github.com/scientific-python/lazy-loader/pull/77)).
+- Bump pre-commit from 3.3.3 to 3.4.0 ([#76](https://github.com/scientific-python/lazy-loader/pull/76)).
+- Use trusted publisher ([#78](https://github.com/scientific-python/lazy-loader/pull/78)).
+- Bump pre-commit from 3.4.0 to 3.5.0 ([#80](https://github.com/scientific-python/lazy-loader/pull/80)).
+- Bump changelist from 0.3 to 0.4 ([#81](https://github.com/scientific-python/lazy-loader/pull/81)).
+- Bump actions/checkout from 3 to 4 ([#82](https://github.com/scientific-python/lazy-loader/pull/82)).
+- Bump actions/setup-python from 4 to 5 ([#85](https://github.com/scientific-python/lazy-loader/pull/85)).
+- Bump pre-commit from 3.5.0 to 3.6.0 ([#84](https://github.com/scientific-python/lazy-loader/pull/84)).
+- Update pre-commit ([#87](https://github.com/scientific-python/lazy-loader/pull/87)).
+- Use setup-python pip cache ([#95](https://github.com/scientific-python/lazy-loader/pull/95)).
+- Bump codecov/codecov-action from 3 to 4 ([#93](https://github.com/scientific-python/lazy-loader/pull/93)).
+- Bump pre-commit from 3.6.0 to 3.6.2 ([#100](https://github.com/scientific-python/lazy-loader/pull/100)).
+- Bump changelist from 0.4 to 0.5 ([#99](https://github.com/scientific-python/lazy-loader/pull/99)).
+- Refuse star imports in stub loader ([#101](https://github.com/scientific-python/lazy-loader/pull/101)).
+- Bump pre-commit from 3.6.2 to 3.7.0 ([#103](https://github.com/scientific-python/lazy-loader/pull/103)).
+- Update pre-commit repos ([#104](https://github.com/scientific-python/lazy-loader/pull/104)).
 
 ## Contributors
 
@@ -67,107 +67,107 @@ duplicates._
 
 # Changelog
 
-## [v0.3](https://github.com/scientific-python/lazy_loader/tree/v0.3) (2023-06-30)
+## [v0.3](https://github.com/scientific-python/lazy-loader/tree/v0.3) (2023-06-30)
 
-[Full Changelog](https://github.com/scientific-python/lazy_loader/compare/v0.2...v0.3)
+[Full Changelog](https://github.com/scientific-python/lazy-loader/compare/v0.2...v0.3)
 
 **Merged pull requests:**
 
-- Announce Python 3.12 support [\#63](https://github.com/scientific-python/lazy_loader/pull/63) ([jarrodmillman](https://github.com/jarrodmillman))
-- Ignore B028 [\#62](https://github.com/scientific-python/lazy_loader/pull/62) ([jarrodmillman](https://github.com/jarrodmillman))
-- Use dependabot to update requirements [\#61](https://github.com/scientific-python/lazy_loader/pull/61) ([jarrodmillman](https://github.com/jarrodmillman))
-- Use dependabot to update GH actions [\#60](https://github.com/scientific-python/lazy_loader/pull/60) ([jarrodmillman](https://github.com/jarrodmillman))
-- Use ruff [\#59](https://github.com/scientific-python/lazy_loader/pull/59) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update requirements [\#58](https://github.com/scientific-python/lazy_loader/pull/58) ([jarrodmillman](https://github.com/jarrodmillman))
-- Warn and discourage lazy.load of subpackages [\#57](https://github.com/scientific-python/lazy_loader/pull/57) ([dschult](https://github.com/dschult))
-- Test on Python 3.12.0-beta.2 [\#53](https://github.com/scientific-python/lazy_loader/pull/53) ([jarrodmillman](https://github.com/jarrodmillman))
+- Announce Python 3.12 support [\#63](https://github.com/scientific-python/lazy-loader/pull/63) ([jarrodmillman](https://github.com/jarrodmillman))
+- Ignore B028 [\#62](https://github.com/scientific-python/lazy-loader/pull/62) ([jarrodmillman](https://github.com/jarrodmillman))
+- Use dependabot to update requirements [\#61](https://github.com/scientific-python/lazy-loader/pull/61) ([jarrodmillman](https://github.com/jarrodmillman))
+- Use dependabot to update GH actions [\#60](https://github.com/scientific-python/lazy-loader/pull/60) ([jarrodmillman](https://github.com/jarrodmillman))
+- Use ruff [\#59](https://github.com/scientific-python/lazy-loader/pull/59) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update requirements [\#58](https://github.com/scientific-python/lazy-loader/pull/58) ([jarrodmillman](https://github.com/jarrodmillman))
+- Warn and discourage lazy.load of subpackages [\#57](https://github.com/scientific-python/lazy-loader/pull/57) ([dschult](https://github.com/dschult))
+- Test on Python 3.12.0-beta.2 [\#53](https://github.com/scientific-python/lazy-loader/pull/53) ([jarrodmillman](https://github.com/jarrodmillman))
 
-## [v0.2](https://github.com/scientific-python/lazy_loader/tree/v0.2)
+## [v0.2](https://github.com/scientific-python/lazy-loader/tree/v0.2)
 
-[Full Changelog](https://github.com/scientific-python/lazy_loader/compare/v0.1...v0.2)
+[Full Changelog](https://github.com/scientific-python/lazy-loader/compare/v0.1...v0.2)
 
 There were no changes since the release candidate, so
 see release notes for v0.2rc0 below for details.
 
-## [v0.2rc0](https://github.com/scientific-python/lazy_loader/tree/v0.2rc0)
+## [v0.2rc0](https://github.com/scientific-python/lazy-loader/tree/v0.2rc0)
 
-[Full Changelog](https://github.com/scientific-python/lazy_loader/compare/v0.1...v0.2rc0)
+[Full Changelog](https://github.com/scientific-python/lazy-loader/compare/v0.1...v0.2rc0)
 
 **Closed issues:**
 
-- Allow to not fail on stub attach in frozen apps [\#38](https://github.com/scientific-python/lazy_loader/issues/38)
-- Stub files with absolute imports [\#36](https://github.com/scientific-python/lazy_loader/issues/36)
-- Help to packaging Debian package [\#35](https://github.com/scientific-python/lazy_loader/issues/35)
-- conda upload [\#33](https://github.com/scientific-python/lazy_loader/issues/33)
-- Possible issues with partial lazy loading [\#32](https://github.com/scientific-python/lazy_loader/issues/32)
-- Type hints/Mypy best practices? [\#28](https://github.com/scientific-python/lazy_loader/issues/28)
-- Re-export non descendant attribute? [\#27](https://github.com/scientific-python/lazy_loader/issues/27)
-- This is awesome [\#6](https://github.com/scientific-python/lazy_loader/issues/6)
+- Allow to not fail on stub attach in frozen apps [\#38](https://github.com/scientific-python/lazy-loader/issues/38)
+- Stub files with absolute imports [\#36](https://github.com/scientific-python/lazy-loader/issues/36)
+- Help to packaging Debian package [\#35](https://github.com/scientific-python/lazy-loader/issues/35)
+- conda upload [\#33](https://github.com/scientific-python/lazy-loader/issues/33)
+- Possible issues with partial lazy loading [\#32](https://github.com/scientific-python/lazy-loader/issues/32)
+- Type hints/Mypy best practices? [\#28](https://github.com/scientific-python/lazy-loader/issues/28)
+- Re-export non descendant attribute? [\#27](https://github.com/scientific-python/lazy-loader/issues/27)
+- This is awesome [\#6](https://github.com/scientific-python/lazy-loader/issues/6)
 
 **Merged pull requests:**
 
-- Add information that `pyi` files are used in runtime when use `attach\_stub` [\#47](https://github.com/scientific-python/lazy_loader/pull/47) ([Czaki](https://github.com/Czaki))
-- Update tests to improve coverage [\#45](https://github.com/scientific-python/lazy_loader/pull/45) ([jarrodmillman](https://github.com/jarrodmillman))
-- Use codecov GH action [\#44](https://github.com/scientific-python/lazy_loader/pull/44) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update year [\#43](https://github.com/scientific-python/lazy_loader/pull/43) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update GH actions [\#42](https://github.com/scientific-python/lazy_loader/pull/42) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update pre-commit [\#41](https://github.com/scientific-python/lazy_loader/pull/41) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update optional depedencies [\#40](https://github.com/scientific-python/lazy_loader/pull/40) ([jarrodmillman](https://github.com/jarrodmillman))
-- Fix extension substitution to work with `\*.pyc` files [\#39](https://github.com/scientific-python/lazy_loader/pull/39) ([Czaki](https://github.com/Czaki))
-- Sort returned \_\_all\_\_ [\#34](https://github.com/scientific-python/lazy_loader/pull/34) ([stefanv](https://github.com/stefanv))
+- Add information that `pyi` files are used in runtime when use `attach\_stub` [\#47](https://github.com/scientific-python/lazy-loader/pull/47) ([Czaki](https://github.com/Czaki))
+- Update tests to improve coverage [\#45](https://github.com/scientific-python/lazy-loader/pull/45) ([jarrodmillman](https://github.com/jarrodmillman))
+- Use codecov GH action [\#44](https://github.com/scientific-python/lazy-loader/pull/44) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update year [\#43](https://github.com/scientific-python/lazy-loader/pull/43) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update GH actions [\#42](https://github.com/scientific-python/lazy-loader/pull/42) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update pre-commit [\#41](https://github.com/scientific-python/lazy-loader/pull/41) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update optional dependencies [\#40](https://github.com/scientific-python/lazy-loader/pull/40) ([jarrodmillman](https://github.com/jarrodmillman))
+- Fix extension substitution to work with `\*.pyc` files [\#39](https://github.com/scientific-python/lazy-loader/pull/39) ([Czaki](https://github.com/Czaki))
+- Sort returned \_\_all\_\_ [\#34](https://github.com/scientific-python/lazy-loader/pull/34) ([stefanv](https://github.com/stefanv))
 
-## [v0.1](https://github.com/scientific-python/lazy_loader/tree/v0.1) (2022-09-21)
+## [v0.1](https://github.com/scientific-python/lazy-loader/tree/v0.1) (2022-09-21)
 
-[Full Changelog](https://github.com/scientific-python/lazy_loader/compare/v0.1rc3...v0.1)
+[Full Changelog](https://github.com/scientific-python/lazy-loader/compare/v0.1rc3...v0.1)
 
 **Merged pull requests:**
 
-- Update classifiers [\#31](https://github.com/scientific-python/lazy_loader/pull/31) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update precommit hooks [\#30](https://github.com/scientific-python/lazy_loader/pull/30) ([jarrodmillman](https://github.com/jarrodmillman))
-- Refer to SPEC for stub usage [\#29](https://github.com/scientific-python/lazy_loader/pull/29) ([stefanv](https://github.com/stefanv))
+- Update classifiers [\#31](https://github.com/scientific-python/lazy-loader/pull/31) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update precommit hooks [\#30](https://github.com/scientific-python/lazy-loader/pull/30) ([jarrodmillman](https://github.com/jarrodmillman))
+- Refer to SPEC for stub usage [\#29](https://github.com/scientific-python/lazy-loader/pull/29) ([stefanv](https://github.com/stefanv))
 
-## [v0.1rc3](https://github.com/scientific-python/lazy_loader/tree/v0.1rc3) (2022-08-29)
+## [v0.1rc3](https://github.com/scientific-python/lazy-loader/tree/v0.1rc3) (2022-08-29)
 
-[Full Changelog](https://github.com/scientific-python/lazy_loader/compare/v0.1rc2...v0.1rc3)
+[Full Changelog](https://github.com/scientific-python/lazy-loader/compare/v0.1rc2...v0.1rc3)
 
 **Merged pull requests:**
 
-- Add test and coverage badges [\#26](https://github.com/scientific-python/lazy_loader/pull/26) ([jarrodmillman](https://github.com/jarrodmillman))
-- Fix typos [\#25](https://github.com/scientific-python/lazy_loader/pull/25) ([jarrodmillman](https://github.com/jarrodmillman))
-- Measure test coverage [\#23](https://github.com/scientific-python/lazy_loader/pull/23) ([jarrodmillman](https://github.com/jarrodmillman))
-- Document release process [\#22](https://github.com/scientific-python/lazy_loader/pull/22) ([jarrodmillman](https://github.com/jarrodmillman))
-- Add classifiers [\#21](https://github.com/scientific-python/lazy_loader/pull/21) ([jarrodmillman](https://github.com/jarrodmillman))
-- Lint toml files [\#20](https://github.com/scientific-python/lazy_loader/pull/20) ([jarrodmillman](https://github.com/jarrodmillman))
-- Test on more versions and platforms [\#19](https://github.com/scientific-python/lazy_loader/pull/19) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update GH actions [\#18](https://github.com/scientific-python/lazy_loader/pull/18) ([jarrodmillman](https://github.com/jarrodmillman))
-- Split out linting CI from testing [\#17](https://github.com/scientific-python/lazy_loader/pull/17) ([jarrodmillman](https://github.com/jarrodmillman))
-- Update precommit hooks [\#16](https://github.com/scientific-python/lazy_loader/pull/16) ([jarrodmillman](https://github.com/jarrodmillman))
-- Specify lower bounds on dependencies [\#15](https://github.com/scientific-python/lazy_loader/pull/15) ([jarrodmillman](https://github.com/jarrodmillman))
-- Lower min required Python version to 3.7 [\#14](https://github.com/scientific-python/lazy_loader/pull/14) ([donatasm](https://github.com/donatasm))
-- feat: add attach_stub function to load imports from type stubs [\#10](https://github.com/scientific-python/lazy_loader/pull/10) ([tlambert03](https://github.com/tlambert03))
-- Avoid conflicts when function is implemented in same-named submodule [\#9](https://github.com/scientific-python/lazy_loader/pull/9) ([stefanv](https://github.com/stefanv))
-- DOC fix missing comma in usage example in README.md [\#7](https://github.com/scientific-python/lazy_loader/pull/7) ([adrinjalali](https://github.com/adrinjalali))
-
-## [v0.1rc2](https://github.com/scientific-python/lazy_loader/tree/v0.1rc2) (2022-03-10)
-
-[Full Changelog](https://github.com/scientific-python/lazy_loader/compare/v0.1rc1...v0.1rc2)
+- Add test and coverage badges [\#26](https://github.com/scientific-python/lazy-loader/pull/26) ([jarrodmillman](https://github.com/jarrodmillman))
+- Fix typos [\#25](https://github.com/scientific-python/lazy-loader/pull/25) ([jarrodmillman](https://github.com/jarrodmillman))
+- Measure test coverage [\#23](https://github.com/scientific-python/lazy-loader/pull/23) ([jarrodmillman](https://github.com/jarrodmillman))
+- Document release process [\#22](https://github.com/scientific-python/lazy-loader/pull/22) ([jarrodmillman](https://github.com/jarrodmillman))
+- Add classifiers [\#21](https://github.com/scientific-python/lazy-loader/pull/21) ([jarrodmillman](https://github.com/jarrodmillman))
+- Lint toml files [\#20](https://github.com/scientific-python/lazy-loader/pull/20) ([jarrodmillman](https://github.com/jarrodmillman))
+- Test on more versions and platforms [\#19](https://github.com/scientific-python/lazy-loader/pull/19) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update GH actions [\#18](https://github.com/scientific-python/lazy-loader/pull/18) ([jarrodmillman](https://github.com/jarrodmillman))
+- Split out linting CI from testing [\#17](https://github.com/scientific-python/lazy-loader/pull/17) ([jarrodmillman](https://github.com/jarrodmillman))
+- Update precommit hooks [\#16](https://github.com/scientific-python/lazy-loader/pull/16) ([jarrodmillman](https://github.com/jarrodmillman))
+- Specify lower bounds on dependencies [\#15](https://github.com/scientific-python/lazy-loader/pull/15) ([jarrodmillman](https://github.com/jarrodmillman))
+- Lower min required Python version to 3.7 [\#14](https://github.com/scientific-python/lazy-loader/pull/14) ([donatasm](https://github.com/donatasm))
+- feat: add attach_stub function to load imports from type stubs [\#10](https://github.com/scientific-python/lazy-loader/pull/10) ([tlambert03](https://github.com/tlambert03))
+- Avoid conflicts when function is implemented in same-named submodule [\#9](https://github.com/scientific-python/lazy-loader/pull/9) ([stefanv](https://github.com/stefanv))
+- DOC fix missing comma in usage example in README.md [\#7](https://github.com/scientific-python/lazy-loader/pull/7) ([adrinjalali](https://github.com/adrinjalali))
+
+## [v0.1rc2](https://github.com/scientific-python/lazy-loader/tree/v0.1rc2) (2022-03-10)
+
+[Full Changelog](https://github.com/scientific-python/lazy-loader/compare/v0.1rc1...v0.1rc2)
 
 **Merged pull requests:**
 
-- Add contributor README [\#5](https://github.com/scientific-python/lazy_loader/pull/5) ([stefanv](https://github.com/stefanv))
-- Simplify delayed exception handling and improve reporting [\#4](https://github.com/scientific-python/lazy_loader/pull/4) ([stefanv](https://github.com/stefanv))
+- Add contributor README [\#5](https://github.com/scientific-python/lazy-loader/pull/5) ([stefanv](https://github.com/stefanv))
+- Simplify delayed exception handling and improve reporting [\#4](https://github.com/scientific-python/lazy-loader/pull/4) ([stefanv](https://github.com/stefanv))
 
-## [v0.1rc1](https://github.com/scientific-python/lazy_loader/tree/v0.1rc1) (2022-03-01)
+## [v0.1rc1](https://github.com/scientific-python/lazy-loader/tree/v0.1rc1) (2022-03-01)
 
-[Full Changelog](https://github.com/scientific-python/lazy_loader/compare/v0.0...v0.1rc1)
+[Full Changelog](https://github.com/scientific-python/lazy-loader/compare/v0.0...v0.1rc1)
 
 **Closed issues:**
 
-- Create package on pypi [\#1](https://github.com/scientific-python/lazy_loader/issues/1)
+- Create package on pypi [\#1](https://github.com/scientific-python/lazy-loader/issues/1)
 
 **Merged pull requests:**
 
-- Run pre-commit hooks [\#3](https://github.com/scientific-python/lazy_loader/pull/3) ([tupui](https://github.com/tupui))
-- Add the packaging infrastructure [\#2](https://github.com/scientific-python/lazy_loader/pull/2) ([tupui](https://github.com/tupui))
+- Run pre-commit hooks [\#3](https://github.com/scientific-python/lazy-loader/pull/3) ([tupui](https://github.com/tupui))
+- Add the packaging infrastructure [\#2](https://github.com/scientific-python/lazy-loader/pull/2) ([tupui](https://github.com/tupui))
 
 \* _This Changelog was automatically generated by [github_changelog_generator](https://github.com/github-changelog-generator/github-changelog-generator)_
diff --git a/MANIFEST.in b/MANIFEST.in
index fc49293..ce1d4c7 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1 +1,9 @@
 include CHANGELOG.md
+include .spin/cmds.py
+recursive-include tests *
+
+global-exclude *~
+global-exclude *.pyc
+
+prune */.pytest_cache
+prune */__pycache__
diff --git a/README.md b/README.md
index 64b3d9c..17c255e 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,8 @@
-[![PyPI](https://img.shields.io/pypi/v/lazy_loader)](https://pypi.org/project/lazy_loader/)
-[![Test status](https://github.com/scientific-python/lazy_loader/workflows/test/badge.svg?branch=main)](https://github.com/scientific-python/lazy_loader/actions?query=workflow%3A%22test%22)
-[![Test coverage](https://codecov.io/gh/scientific-python/lazy_loader/branch/main/graph/badge.svg)](https://app.codecov.io/gh/scientific-python/lazy_loader/branch/main)
+[![PyPI](https://img.shields.io/pypi/v/lazy-loader)](https://pypi.org/project/lazy-loader/)
+[![Test status](https://github.com/scientific-python/lazy-loader/workflows/test/badge.svg?branch=main)](https://github.com/scientific-python/lazy-loader/actions?query=workflow%3A%22test%22)
+[![Test coverage](https://codecov.io/gh/scientific-python/lazy-loader/branch/main/graph/badge.svg)](https://app.codecov.io/gh/scientific-python/lazy-loader/branch/main)
 
-`lazy_loader` makes it easy to load subpackages and functions on demand.
+`lazy-loader` makes it easy to load subpackages and functions on demand.
 
 ## Motivation
 
@@ -14,10 +14,10 @@ For a more detailed discussion, see [the SPEC](https://scientific-python.org/spe
 ## Installation
 
 ```
-pip install -U lazy_loader
+pip install -U lazy-loader
 ```
 
-We recommend using `lazy_loader` with Python >= 3.11.
+We recommend using `lazy-loader` with Python >= 3.11.
 If using Python 3.11, please upgrade to 3.11.9 or later.
 If using Python 3.12, please upgrade to 3.12.3 or later.
 These versions [avoid](https://github.com/python/cpython/pull/114781) a [known race condition](https://github.com/python/cpython/issues/114763).
diff --git a/RELEASE.md b/RELEASE.md
index cd1585c..a749d39 100644
--- a/RELEASE.md
+++ b/RELEASE.md
@@ -1,4 +1,4 @@
-# Release process for `lazy_loader`
+# Release process for `lazy-loader`
 
 ## Introduction
 
@@ -17,19 +17,22 @@ Example `version number`
       export VERSION=<version number>
       export PREVIOUS=<previous version number>
       export ORG="scientific-python"
-      export REPO="lazy_loader"
+      export REPO="lazy-loader"
+      export LOG="CHANGELOG.md"
 
 - Autogenerate release notes
 
-      changelist ${ORG}/${REPO} v${PREVIOUS} main --version ${VERSION}
+      changelist ${ORG}/${REPO} v${PREVIOUS} main --version ${VERSION} --config pyproject.toml --out ${VERSION}.md
 
 - Put the output of the above command at the top of `CHANGELOG.md`
 
-- Update `version` in `pyproject.toml`.
+      cat ${VERSION}.md | cat - ${LOG} > temp && mv temp ${LOG}
+
+- Update `version` in `lazy_loader/__init__.py`.
 
 - Commit changes:
 
-      git add pyproject.toml CHANGELOG.md
+      git add lazy_loader/__init__.py ${LOG}
       git commit -m "Designate ${VERSION} release"
 
 - Tag the release in git:
@@ -43,13 +46,25 @@ Example `version number`
 
       git push --tags origin main
 
-  where `origin` is the name of the `github.com:scientific-python/lazy_loader`
+  where `origin` is the name of the `github.com:scientific-python/lazy-loader`
   repository
 
-- Update `version` in `pyproject.toml`.
+- Create release from tag
+
+      - go to https://github.com/scientific-python/lazy-loader/releases/new?tag=v${VERSION}
+      - add v${VERSION} for the `Release title`
+      - paste contents (or upload) of ${VERSION}.md in the `Describe this release section`
+      - if pre-release check the box labelled `Set as a pre-release`
+
+- Update https://github.com/scientific-python/lazy-loader/milestones:
+
+      - close old milestone
+      - ensure new milestone exists (perhaps setting due date)
+
+- Update `version` in `lazy_loader/__init__.py`.
 
 - Commit changes:
 
-      git add pyproject.toml
+      git add lazy_loader/__init__.py
       git commit -m 'Bump version'
       git push origin main
diff --git a/lazy_loader/tests/fake_pkg/__init__.pyi b/lazy_loader/tests/fake_pkg/__init__.pyi
deleted file mode 100644
index d3349bb..0000000
--- a/lazy_loader/tests/fake_pkg/__init__.pyi
+++ /dev/null
@@ -1 +0,0 @@
-from .some_func import some_func
diff --git a/pyproject.toml b/pyproject.toml
index c81bd40..828c1ba 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,58 +3,116 @@ requires = ["setuptools>=61.2"]
 build-backend = "setuptools.build_meta"
 
 [project]
-name = "lazy_loader"
-requires-python = ">=3.7"
+name = "lazy-loader"
+requires-python = ">=3.9"
 authors = [{name = "Scientific Python Developers"}]
 readme = "README.md"
-license = {file = "LICENSE.md"}
+license = "BSD-3-Clause"
 dynamic = ['version']
 classifiers = [
-  "Development Status :: 4 - Beta",
-  "License :: OSI Approved :: BSD License",
+  "Development Status :: 5 - Production/Stable",
   "Programming Language :: Python :: 3",
-  "Programming Language :: Python :: 3.7",
-  "Programming Language :: Python :: 3.8",
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
 ]
 description = "Makes it easy to load subpackages and functions on demand."
 dependencies = [
   "packaging",
-  "importlib_metadata; python_version < '3.8'",
 ]
 
 [project.optional-dependencies]
-test = ["pytest >= 7.4", "pytest-cov >= 4.1"]
-lint = ["pre-commit == 3.7.0"]
-dev = ["changelist == 0.5"]
+test = ["pytest >= 8.0", "pytest-cov >= 5.0", "coverage[toml] >= 7.2"]
+lint = ["pre-commit == 4.2.0"]
+dev = ["changelist == 0.5", "spin == 0.14"]
 
 [project.urls]
 Home = "https://scientific-python.org/specs/spec-0001/"
-Source = "https://github.com/scientific-python/lazy_loader"
+Source = "https://github.com/scientific-python/lazy-loader"
 
+[tool.setuptools.dynamic.version]
+attr = 'lazy_loader.__version__'
 
 [tool.changelist]
 ignored_user_logins = ["dependabot[bot]", "pre-commit-ci[bot]", "web-flow"]
 
-[tool.setuptools.dynamic.version]
-attr = 'lazy_loader.__version__'
+[tool.pytest.ini_options]
+minversion = "8.0"
+addopts = ["-ra", "--showlocals", "--strict-markers", "--strict-config"]
+xfail_strict = true
+filterwarnings = ["error"]
+log_cli_level = "info"
 
 [tool.ruff]
-line-length = 88
-target-version = "py37"
-select = [
-    "C",
-    "E",
-    "F",
-    "W",
-    "B",
-    "I",
-    "UP",
-]
-ignore = ["B018", "B028"]
 exclude = [
-  "lazy_loader/tests/fake_pkg/__init__.pyi",
+  "tests/fake_pkg/__init__.pyi",
+]
+
+[tool.ruff.lint]
+extend-select = [
+  "B",        # flake8-bugbear
+  "I",        # isort
+  "ARG",      # flake8-unused-arguments
+  "C4",       # flake8-comprehensions
+  "EM",       # flake8-errmsg
+  "ICN",      # flake8-import-conventions
+  "G",        # flake8-logging-format
+  "PGH",      # pygrep-hooks
+  "PIE",      # flake8-pie
+  "PL",       # pylint
+  "PT",       # flake8-pytest-style
+#  "PTH",      # flake8-use-pathlib
+  "RET",      # flake8-return
+  "RUF",      # Ruff-specific
+  "SIM",      # flake8-simplify
+  "T20",      # flake8-print
+  "UP",       # pyupgrade
+  "YTT",      # flake8-2020
+  "EXE",      # flake8-executable
+  "NPY",      # NumPy specific rules
+  "PD",       # pandas-vet
+  "FURB",     # refurb
+  "PYI",      # flake8-pyi
+]
+ignore = [
+  "PLR09",    # Too many <...>
+  "PLR2004",  # Magic value used in comparison
+  "ISC001",   # Conflicts with formatter
+  "B018",     # Found useless expression
+  "B028",     # No explicit `stacklevel` keyword argument found
+  "PT011",    # `pytest.raises(ValueError)` is too broad
+  "EM102",    # Exception must not use an f-string literal
+  "EM101",    # Exception must not use a string literal
+  "RET505",   # Unnecessary `elif` after `return` statement
+  "SIM108",   # Use ternary operator
+]
+
+[tool.ruff.lint.per-file-ignores]
+"tests/test_*.py" = [
+  "ARG001",  # Pytest fixtures are passed as arguments
+]
+
+[tool.ruff.format]
+docstring-code-format = true
+
+[tool.coverage.run]
+branch = true
+source = ["lazy_loader", "tests"]
+
+[tool.coverage.paths]
+source = [
+  "src/lazy_loader",
+  "*/site-packages/lazy_loader",
+]
+
+[tool.spin]
+package = 'lazy_loader'
+
+[tool.spin.commands]
+Build = [
+    'spin.cmds.pip.install',
+    '.spin/cmds.py:test',
+    'spin.cmds.build.sdist',
 ]
diff --git a/lazy_loader/__init__.py b/src/lazy_loader/__init__.py
similarity index 84%
rename from lazy_loader/__init__.py
rename to src/lazy_loader/__init__.py
index 5f25913..0b0243e 100644
--- a/lazy_loader/__init__.py
+++ b/src/lazy_loader/__init__.py
@@ -14,8 +14,8 @@
 import types
 import warnings
 
-__version__ = "0.4"
-__all__ = ["attach", "load", "attach_stub"]
+__version__ = "0.5rc0.dev0"
+__all__ = ["attach", "attach_stub", "load"]
 
 
 threadlock = threading.Lock()
@@ -38,13 +38,9 @@ def attach(package_name, submodules=None, submod_attrs=None):
     The typical way to call this function, replacing the above imports, is::
 
       __getattr__, __dir__, __all__ = lazy.attach(
-        __name__,
-        ['mysubmodule', 'anothersubmodule'],
-        {'foo': ['someattr']}
+          __name__, ["mysubmodule", "anothersubmodule"], {"foo": ["someattr"]}
       )
 
-    This functionality requires Python 3.7 or higher.
-
     Parameters
     ----------
     package_name : str
@@ -94,13 +90,13 @@ def __getattr__(name):
             raise AttributeError(f"No {package_name} attribute {name}")
 
     def __dir__():
-        return __all__
+        return __all__.copy()
 
     if os.environ.get("EAGER_IMPORT", ""):
         for attr in set(attr_to_modules.keys()) | submodules:
             __getattr__(attr)
 
-    return __getattr__, __dir__, list(__all__)
+    return __getattr__, __dir__, __all__.copy()
 
 
 class DelayedImportErrorModule(types.ModuleType):
@@ -110,19 +106,16 @@ def __init__(self, frame_data, *args, message, **kwargs):
         super().__init__(*args, **kwargs)
 
     def __getattr__(self, x):
-        if x in ("__class__", "__file__", "__frame_data", "__message"):
-            super().__getattr__(x)
-        else:
-            fd = self.__frame_data
-            raise ModuleNotFoundError(
-                f"{self.__message}\n\n"
-                "This error is lazily reported, having originally occured in\n"
-                f'  File {fd["filename"]}, line {fd["lineno"]}, in {fd["function"]}\n\n'
-                f'----> {"".join(fd["code_context"] or "").strip()}'
-            )
+        fd = self.__frame_data
+        raise ModuleNotFoundError(
+            f"{self.__message}\n\n"
+            "This error is lazily reported, having originally occurred in\n"
+            f"  File {fd['filename']}, line {fd['lineno']}, in {fd['function']}\n\n"
+            f"----> {''.join(fd['code_context'] or '').strip()}"
+        )
 
 
-def load(fullname, *, require=None, error_on_import=False):
+def load(fullname, *, require=None, error_on_import=False, suppress_warning=False):
     """Return a lazily imported proxy for a module.
 
     We often see the following pattern::
@@ -164,7 +157,7 @@ def myfunc():
     fullname : str
         The full name of the module or submodule to import.  For example::
 
-          sp = lazy.load('scipy')  # import scipy as sp
+          sp = lazy.load("scipy")  # import scipy as sp
 
     require : str
         A dependency requirement as defined in PEP-508.  For example::
@@ -178,6 +171,10 @@ def myfunc():
         Whether to postpone raising import errors until the module is accessed.
         If set to `True`, import errors are raised as soon as `load` is called.
 
+    suppress_warning : bool
+        Whether to prevent emitting a warning when loading subpackages.
+        If set to `True`, no warning will occur.
+
     Returns
     -------
     pm : importlib.util._LazyModule
@@ -193,10 +190,10 @@ def myfunc():
         if have_module and require is None:
             return module
 
-        if "." in fullname:
+        if not suppress_warning and "." in fullname:
             msg = (
                 "subpackages can technically be lazily loaded, but it causes the "
-                "package to be eagerly loaded even if it is already lazily loaded."
+                "package to be eagerly loaded even if it is already lazily loaded. "
                 "So, you probably shouldn't use subpackages with this lazy feature."
             )
             warnings.warn(msg, RuntimeWarning)
@@ -226,21 +223,19 @@ def myfunc():
                 raise ModuleNotFoundError(not_found_message)
             import inspect
 
-            try:
-                parent = inspect.stack()[1]
-                frame_data = {
-                    "filename": parent.filename,
-                    "lineno": parent.lineno,
-                    "function": parent.function,
-                    "code_context": parent.code_context,
-                }
-                return DelayedImportErrorModule(
-                    frame_data,
-                    "DelayedImportErrorModule",
-                    message=not_found_message,
-                )
-            finally:
-                del parent
+            parent = inspect.stack()[1]
+            frame_data = {
+                "filename": parent.filename,
+                "lineno": parent.lineno,
+                "function": parent.function,
+                "code_context": parent.code_context,
+            }
+            del parent
+            return DelayedImportErrorModule(
+                frame_data,
+                "DelayedImportErrorModule",
+                message=not_found_message,
+            )
 
         if spec is not None:
             module = importlib.util.module_from_spec(spec)
@@ -269,16 +264,13 @@ def _check_requirement(require: str) -> bool:
         True if the installed version of the dependency matches
         the specified version, False otherwise.
     """
-    import packaging.requirements
+    import importlib.metadata
 
-    try:
-        import importlib.metadata as importlib_metadata
-    except ImportError:  # PY37
-        import importlib_metadata
+    import packaging.requirements
 
     req = packaging.requirements.Requirement(require)
     return req.specifier.contains(
-        importlib_metadata.version(req.name),
+        importlib.metadata.version(req.name),
         prereleases=True,
     )
 
diff --git a/lazy_loader/tests/__init__.py b/tests/__init__.py
similarity index 100%
rename from lazy_loader/tests/__init__.py
rename to tests/__init__.py
diff --git a/lazy_loader/tests/fake_pkg/__init__.py b/tests/fake_pkg/__init__.py
similarity index 54%
rename from lazy_loader/tests/fake_pkg/__init__.py
rename to tests/fake_pkg/__init__.py
index 540fd73..39f038d 100644
--- a/lazy_loader/tests/fake_pkg/__init__.py
+++ b/tests/fake_pkg/__init__.py
@@ -1,5 +1,5 @@
 import lazy_loader as lazy
 
 __getattr__, __lazy_dir__, __all__ = lazy.attach(
-    __name__, submod_attrs={"some_func": ["some_func"]}
+    __name__, submod_attrs={"some_func": ["some_func", "aux_func"]}
 )
diff --git a/tests/fake_pkg/__init__.pyi b/tests/fake_pkg/__init__.pyi
new file mode 100644
index 0000000..8ace2b6
--- /dev/null
+++ b/tests/fake_pkg/__init__.pyi
@@ -0,0 +1 @@
+from .some_func import aux_func, some_func
diff --git a/lazy_loader/tests/fake_pkg/some_func.py b/tests/fake_pkg/some_func.py
similarity index 57%
rename from lazy_loader/tests/fake_pkg/some_func.py
rename to tests/fake_pkg/some_func.py
index 10e99ed..5b7c10e 100644
--- a/lazy_loader/tests/fake_pkg/some_func.py
+++ b/tests/fake_pkg/some_func.py
@@ -1,3 +1,6 @@
 def some_func():
     """Function with same name as submodule."""
-    pass
+
+
+def aux_func():
+    """Auxiliary function."""
diff --git a/lazy_loader/tests/import_np_parallel.py b/tests/import_np_parallel.py
similarity index 100%
rename from lazy_loader/tests/import_np_parallel.py
rename to tests/import_np_parallel.py
diff --git a/lazy_loader/tests/test_lazy_loader.py b/tests/test_lazy_loader.py
similarity index 61%
rename from lazy_loader/tests/test_lazy_loader.py
rename to tests/test_lazy_loader.py
index 19187ba..44e9c3d 100644
--- a/lazy_loader/tests/test_lazy_loader.py
+++ b/tests/test_lazy_loader.py
@@ -10,6 +10,26 @@
 import lazy_loader as lazy
 
 
+@pytest.fixture
+def clean_fake_pkg():
+    yield
+    sys.modules.pop("tests.fake_pkg.some_func", None)
+    sys.modules.pop("tests.fake_pkg", None)
+    sys.modules.pop("tests", None)
+
+
+@pytest.mark.parametrize("attempt", [1, 2])
+def test_cleanup_fixture(clean_fake_pkg, attempt):
+    assert "tests.fake_pkg" not in sys.modules
+    assert "tests.fake_pkg.some_func" not in sys.modules
+    from tests import fake_pkg
+
+    assert "tests.fake_pkg" in sys.modules
+    assert "tests.fake_pkg.some_func" not in sys.modules
+    assert isinstance(fake_pkg.some_func, types.FunctionType)
+    assert "tests.fake_pkg.some_func" in sys.modules
+
+
 def test_lazy_import_basics():
     math = lazy.load("math")
     anything_not_real = lazy.load("anything_not_real")
@@ -17,25 +37,19 @@ def test_lazy_import_basics():
     # Now test that accessing attributes does what it should
     assert math.sin(math.pi) == pytest.approx(0, 1e-6)
     # poor-mans pytest.raises for testing errors on attribute access
-    try:
+    with pytest.raises(ModuleNotFoundError):
         anything_not_real.pi
-        raise AssertionError()  # Should not get here
-    except ModuleNotFoundError:
-        pass
     assert isinstance(anything_not_real, lazy.DelayedImportErrorModule)
     # see if it changes for second access
-    try:
+    with pytest.raises(ModuleNotFoundError):
         anything_not_real.pi
-        raise AssertionError()  # Should not get here
-    except ModuleNotFoundError:
-        pass
 
 
 def test_lazy_import_subpackages():
     with pytest.warns(RuntimeWarning):
         hp = lazy.load("html.parser")
     assert "html" in sys.modules
-    assert type(sys.modules["html"]) == type(pytest)
+    assert type(sys.modules["html"]) is type(pytest)
     assert isinstance(hp, importlib.util._LazyModule)
     assert "html.parser" in sys.modules
     assert sys.modules["html.parser"] == hp
@@ -68,11 +82,8 @@ def test_lazy_import_nonbuiltins():
     if not isinstance(np, lazy.DelayedImportErrorModule):
         assert np.sin(np.pi) == pytest.approx(0, 1e-6)
     if isinstance(sp, lazy.DelayedImportErrorModule):
-        try:
+        with pytest.raises(ModuleNotFoundError):
             sp.pi
-            raise AssertionError()
-        except ModuleNotFoundError:
-            pass
 
 
 def test_lazy_attach():
@@ -103,19 +114,68 @@ def test_lazy_attach():
         if v is not None:
             assert locls[k] == v
 
+    # Exercise __getattr__, though it will just error
+    with pytest.raises(ImportError):
+        locls["__getattr__"]("mysubmodule")
 
-def test_attach_same_module_and_attr_name():
-    from lazy_loader.tests import fake_pkg
+    # Attribute is supposed to be imported, error on submodule load
+    with pytest.raises(ImportError):
+        locls["__getattr__"]("some_var_or_func")
 
-    # Grab attribute twice, to ensure that importing it does not
-    # override function by module
-    assert isinstance(fake_pkg.some_func, types.FunctionType)
-    assert isinstance(fake_pkg.some_func, types.FunctionType)
+    # Attribute is unknown, raise AttributeError
+    with pytest.raises(AttributeError):
+        locls["__getattr__"]("unknown_attr")
 
-    # Ensure imports from submodule still work
-    from lazy_loader.tests.fake_pkg.some_func import some_func
 
-    assert isinstance(some_func, types.FunctionType)
+def test_lazy_attach_noattrs():
+    name = "mymod"
+    submods = ["mysubmodule", "anothersubmodule"]
+    _, _, all_ = lazy.attach(name, submods)
+
+    assert all_ == sorted(submods)
+
+
+def test_lazy_attach_returns_copies():
+    _get, _dir, _all = lazy.attach(
+        __name__, ["my_submodule", "another_submodule"], {"foo": ["some_attr"]}
+    )
+    assert _dir() is not _dir()
+    assert _dir() == _all
+    assert _dir() is not _all
+
+    expected = ["another_submodule", "my_submodule", "some_attr"]
+    assert _dir() == expected
+    assert _all == expected
+    assert _dir() is not _all
+
+    _dir().append("modify_returned_list")
+    assert _dir() == expected
+    assert _all == expected
+    assert _dir() is not _all
+
+    _all.append("modify_returned_all")
+    assert _dir() == expected
+    assert _all == [*expected, "modify_returned_all"]
+
+
+@pytest.mark.parametrize("eager_import", [False, True])
+def test_attach_same_module_and_attr_name(clean_fake_pkg, eager_import):
+    env = {}
+    if eager_import:
+        env["EAGER_IMPORT"] = "1"
+
+    with mock.patch.dict(os.environ, env):
+        from tests import fake_pkg
+
+        # Grab attribute twice, to ensure that importing it does not
+        # override function by module
+        assert isinstance(fake_pkg.some_func, types.FunctionType)
+        assert isinstance(fake_pkg.some_func, types.FunctionType)
+
+        # Ensure imports from submodule still work
+        from tests.fake_pkg.some_func import some_func
+
+        assert isinstance(some_func, types.FunctionType)
 
 
 FAKE_STUB = """
@@ -134,7 +194,7 @@ def test_stub_loading(tmp_path):
 
 
 def test_stub_loading_parity():
-    from lazy_loader.tests import fake_pkg
+    from tests import fake_pkg
 
     from_stub = lazy.attach_stub(fake_pkg.__name__, fake_pkg.__file__)
     stub_getter, stub_dir, stub_all = from_stub
@@ -160,10 +220,8 @@ def test_stub_loading_errors(tmp_path):
 
 
 def test_require_kwarg():
-    have_importlib_metadata = importlib.util.find_spec("importlib.metadata") is not None
-    dot = "." if have_importlib_metadata else "_"
     # Test with a module that definitely exists, behavior hinges on requirement
-    with mock.patch(f"importlib{dot}metadata.version") as version:
+    with mock.patch("importlib.metadata.version") as version:
         version.return_value = "1.0.0"
         math = lazy.load("math", require="somepkg >= 2.0")
         assert isinstance(math, lazy.DelayedImportErrorModule)
@@ -175,6 +233,10 @@ def test_require_kwarg():
         math = lazy.load("math", require="somepkg >= 2.0")
         assert isinstance(math, lazy.DelayedImportErrorModule)
 
+        # Eager failure
+        with pytest.raises(ModuleNotFoundError):
+            lazy.load("math", require="somepkg >= 2.0", error_on_import=True)
+
     # When a module can be loaded but the version can't be checked,
     # raise a ValueError
     with pytest.raises(ValueError):
@@ -188,5 +250,6 @@ def test_parallel_load():
         [
             sys.executable,
             os.path.join(os.path.dirname(__file__), "import_np_parallel.py"),
-        ]
+        ],
+        check=True,
     )