From 617315ade81b18b767ba3162c58cf9920a1f9d86 Mon Sep 17 00:00:00 2001
From: Hynek Schlawack <hs@ox.cx>
Date: Fri, 23 Sep 2022 10:22:16 +0200
Subject: [PATCH] Switch from tox to nox

This greatly simplifies (and makes more idiomatic) both our local tests and CI.
---
 setup.cfg => .flake8                 |  3 +
 .github/workflows/ci.yml             | 57 +++++++---------
 .gitignore                           |  2 +-
 CONTRIBUTING.rst                     | 22 +++----
 MANIFEST.in                          |  5 +-
 noxfile.py                           | 97 ++++++++++++++++++++++++++++
 pyproject.toml                       |  9 ++-
 setup.py                             |  1 -
 src/towncrier/_project.py            |  5 +-
 src/towncrier/newsfragments/430.misc |  2 +
 src/towncrier/test/test_project.py   | 17 +++++
 tox.ini                              | 68 -------------------
 tox_build.sh                         | 16 -----
 13 files changed, 165 insertions(+), 139 deletions(-)
 rename setup.cfg => .flake8 (53%)
 create mode 100644 noxfile.py
 create mode 100644 src/towncrier/newsfragments/430.misc
 delete mode 100644 tox.ini
 delete mode 100644 tox_build.sh

diff --git a/setup.cfg b/.flake8
similarity index 53%
rename from setup.cfg
rename to .flake8
index 9b086e81..3907f28c 100644
--- a/setup.cfg
+++ b/.flake8
@@ -1,3 +1,6 @@
 [flake8]
 # Allow for longer test strings. Code is formatted to 88 columns by Black.
 max-line-length = 99
+extend-ignore =
+    # Conflict between flake8 & black about whitespace in slices.
+    E203
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 741df488..cf0f9245 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,27 +22,25 @@ jobs:
             runs-on: ubuntu-latest
         python:
           - name: CPython 3.9
-            tox: py39
             action: 3.9
         task:
           - name: Build
-            tox: build
+            nox: build
 
     steps:
     - uses: actions/checkout@v3
 
     - name: Set up ${{ matrix.python.name }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python.action }}
 
     - name: Install dependencies
-      run: python -m pip install --upgrade pip tox
+      run: python -m pip install --upgrade pip nox
 
     - uses: twisted/python-info-action@v1
 
-    - name: Tox
-      run: tox -c tox.ini -e ${{ matrix.task.tox }}
+    - run: nox -e ${{ matrix.task.nox }}
 
     - name: Publish
       uses: actions/upload-artifact@v3
@@ -60,29 +58,22 @@ jobs:
       matrix:
         python:
           - name: CPython 3.7
-            tox: py37
             action: 3.7
           - name: CPython 3.8
-            tox: py38
             action: 3.8
           - name: CPython 3.9
-            tox: py39
             action: 3.9
           - name: CPython 3.10
-            tox: py310
             action: '3.10'
           - name: CPython 3.11
-            tox: py311
             action: '3.11.0-beta - 3.11'
           - name: PyPy 3.7
-            tox: pypy37
-            action: pypy-3.7
+            action: pypy3.7
           - name: PyPy 3.8
-            tox: pypy38
-            action: pypy-3.8
+            action: pypy3.8
         task:
           - name: Test
-            tox: tests
+            nox: tests
 
     steps:
     - uses: actions/checkout@v3
@@ -94,17 +85,16 @@ jobs:
         path: dist/
 
     - name: Set up ${{ matrix.python.name }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python.action }}
 
     - name: Install dependencies
-      run: python -m pip install --upgrade pip tox codecov coverage[toml]
+      run: python -m pip install --upgrade pip nox codecov coverage[toml]
 
     - uses: twisted/python-info-action@v1
 
-    - name: Tox
-      run: tox -c tox.ini --installpkg dist/*.whl -e ${{ matrix.python.tox }}-tests
+    - run: nox --python ${{ matrix.python.action }} -e ${{ matrix.task.nox }} -- --use-wheel dist/*.whl
 
     - name: Codecov
       run: |
@@ -121,11 +111,10 @@ jobs:
       matrix:
         python:
           - name: CPython 3.9
-            tox: py39
             action: '3.9'
         task:
           - name: Test
-            tox: tests
+            nox: tests
 
     steps:
     - uses: actions/checkout@v3
@@ -137,17 +126,16 @@ jobs:
         path: dist/
 
     - name: Set up ${{ matrix.python.name }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python.action }}
 
     - name: Install dependencies
-      run: python -m pip install --upgrade pip tox codecov coverage[toml]
+      run: python -m pip install --upgrade pip nox codecov coverage[toml]
 
     - uses: twisted/python-info-action@v1
 
-    - name: Tox
-      run: tox -c tox.ini --installpkg dist/*.whl -e ${{ matrix.python.tox }}-tests
+    - run: nox --python ${{ matrix.python.action }} -e ${{ matrix.task.nox }} -- --use-wheel dist/*.whl
 
     - name: Codecov
       run: |
@@ -165,17 +153,16 @@ jobs:
           # Using second most recent minor release for whatever little
           # increase in stability over using the latest minor.
           - name: CPython 3.9
-            tox: py39
             python-version: '3.9'
         task:
           - name: Check Newsfragment
-            tox: check-newsfragment
+            nox: check_newsfragment
             run-if: ${{ github.head_ref != 'pre-commit-ci-update-config' }}
           - name: Check package manifest
-            tox: check-manifest
+            nox: check_manifest
             run-if: true
           - name: Check mypy
-            tox: typecheck
+            nox: typecheck
             run-if: true
 
     steps:
@@ -190,18 +177,18 @@ jobs:
         path: dist/
 
     - name: Set up ${{ matrix.python.name }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python.python-version }}
 
     - name: Install dependencies
-      run: python -m pip install --upgrade pip tox
+      run: python -m pip install --upgrade pip nox
 
     - uses: twisted/python-info-action@v1
 
-    - name: Tox
+    - run: nox -e ${{ matrix.task.nox }}
       if: ${{ matrix.task.run-if }}
-      run: tox -c tox.ini -e ${{ matrix.task.tox }}
+
 
   pypi-publish:
     # https://github.community/t/is-it-possible-to-require-all-github-actions-tasks-to-pass-without-enumerating-them/117957/4?u=graingert
@@ -222,7 +209,7 @@ jobs:
         path: dist/
 
     - name: Set up Python
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v4
       with:
         python-version: 3.9
 
diff --git a/.gitignore b/.gitignore
index 75e82d46..c44127a6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,7 +18,7 @@ apidocs/
 *.pyproj
 .DS_Store
 .eggs
-.tox/
+.nox/
 .coverage.*
 .vscode
 .idea
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 6dd5b340..e69f970b 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -88,7 +88,7 @@ We recommend the following workflow:
 Running the test suite
 ----------------------
 
-We use the `twisted.trial`_ module and `tox`_ to run tests against all supported
+We use the `twisted.trial`_ module and `nox`_ to run tests against all supported
 Python versions and operating systems.
 
 The following list contains some ways how to run the test suite:
@@ -109,26 +109,26 @@ The following list contains some ways how to run the test suite:
   This will invoke a PDB session. If you press ``c`` it will continue running
   the test suite until it runs into an error.
 
-* To run all tests against all supported versions, install tox and use::
+* To run all tests against all supported versions, install nox and use::
 
-    $ tox
+    $ nox
 
-  You may want to add the ``--skip-missing-interpreters`` option to avoid errors
+  You may want to add the ``--no-error-on-missing-interpreters`` option to avoid errors
   when a specific Python interpreter version couldn't be found.
 
 *  To get a complete list of the available targets, run::
 
-    $ tox -av
+    $ nox -l
 
 * To run only a specific test only, use the ``towncrier.test.FILE.CLASS.METHOD`` syntax,
   for example::
 
-    $ tox -- towncrier.test.test_project.InvocationTests.test_version
+    $ nox -e tests -- towncrier.test.test_project.InvocationTests.test_version
 
 * To run some quality checks before you create the pull request,
   we recommend using this call::
 
-    $ tox -e pre-commit,check-manifest,check-newsfragment
+    $ nox -e pre_commit check_manifest check_newsfragment
 
 * Or enable `pre-commit` as a git hook::
 
@@ -136,15 +136,15 @@ The following list contains some ways how to run the test suite:
     $ pre-commit install
 
 
-**Please note**: If the test suite works in tox, but doesn't by calling
+**Please note**: If the test suite works in nox, but doesn't by calling
 ``trial``, it could be that you've got GPG-signing active for git commits which
 fails with our dummy test commits.
 
 .. ### Links
 
-.. _flake8: https://flake8.rtfd.io
+.. _flake8: https://flake8.pycqa.org/
 .. _GitHub Discussions: https://github.com/twisted/towncrier/discussions
 .. _issues:  https://github.com/twisted/towncrier/issues
 .. _pull request: https://github.com/twisted/towncrier/pulls
-.. _tox: https://tox.rtfd.org/
-.. _twisted.trial: https://twistedmatrix.com/trac/wiki/TwistedTrial
+.. _nox: https://nox.thea.codes/
+.. _twisted.trial: https://github.com/twisted/trac-wiki-archive/blob/trunk/TwistedTrial.mediawiki
diff --git a/MANIFEST.in b/MANIFEST.in
index a2261b30..9494555b 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -3,11 +3,10 @@ include .coveragerc
 include LICENSE
 include CODE_OF_CONDUCT.md
 include pyproject.toml
-include tox.ini
-include tox_build.sh
-include tox_check-release.sh
+include noxfile.py
 include *.yaml
 include .git-blame-ignore-revs
+include .flake8
 recursive-include src *.rst
 
 exclude bin
diff --git a/noxfile.py b/noxfile.py
new file mode 100644
index 00000000..38b65b98
--- /dev/null
+++ b/noxfile.py
@@ -0,0 +1,97 @@
+from __future__ import annotations
+
+import os
+
+import nox
+
+
+nox.options.sessions = ["pre_commit", "docs", "typecheck", "tests"]
+nox.options.reuse_existing_virtualenvs = True
+nox.options.error_on_external_run = True
+
+
+@nox.session
+def pre_commit(session: nox.Session) -> None:
+    session.install("pre-commit")
+
+    session.run("pre-commit", "run", "--all-files", "--show-diff-on-failure")
+
+
+@nox.session(python=["pypy3.7", "pypy3.8", "3.7", "3.8", "3.9", "3.10", "3.11"])
+def tests(session: nox.Session) -> None:
+    session.install("Twisted", "coverage[toml]")
+    posargs = list(session.posargs)
+
+    try:
+        # Allow `--use-wheel path/to/wheel.whl` to be passed.
+        i = session.posargs.index("--use-wheel")
+        session.install(session.posargs[i + 1])
+        del posargs[i : i + 2]
+    except ValueError:
+        session.install(".")
+
+    if not posargs:
+        posargs = ["towncrier"]
+
+    session.run("coverage", "run", "--module", "twisted.trial", *posargs)
+
+    if os.environ.get("CI") != "true":
+        session.notify("coverage_report")
+    else:
+        session.run("coverage", "combine")
+
+
+@nox.session
+def coverage_report(session: nox.Session) -> None:
+    session.install("coverage[toml]")
+
+    session.run("coverage", "combine")
+    session.run("coverage", "report")
+
+
+@nox.session
+def check_newsfragment(session: nox.Session) -> None:
+    session.install(".")
+    session.run("python", "-m", "towncrier.check", "--compare-with", "origin/trunk")
+
+
+@nox.session
+def check_manifest(session: nox.Session) -> None:
+    session.install("check-manifest")
+    session.run("check-manifest")
+
+
+@nox.session
+def typecheck(session: nox.Session) -> None:
+    session.install(".", "mypy", "types-setuptools")
+    session.run("mypy", "src")
+
+
+@nox.session
+def docs(session: nox.Session) -> None:
+    session.install(".[dev]")
+
+    session.run(
+        # fmt: off
+        "python", "-m", "sphinx",
+        "-T", "-E",
+        "-W", "--keep-going",
+        "-b", "html",
+        "-d", "docs/_build/doctrees",
+        "-D", "language=en",
+        "docs",
+        "docs/_build/html",
+        # fmt: on
+    )
+
+
+@nox.session
+def build(session: nox.Session) -> None:
+    session.install("build", "check-manifest>=0.44", "twine")
+
+    session.run("check-manifest", "--verbose")
+    # If no argument is passed, build builds an sdist and then a wheel from
+    # that sdist.
+    session.run("python", "-m", "build")
+
+    session.run("twine", "check", "dist/*")
diff --git a/pyproject.toml b/pyproject.toml
index 8cd04260..bff18919 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,7 +41,7 @@ exclude = '''
   /(
       \.eggs         # exclude a few common directories in the
     | \.git          # root of the project
-    | \.tox
+    | \.nox
     | \.venv
     | \.env
     | env
@@ -71,6 +71,11 @@ module = 'click_default_group'
 # 2022-09-04: This library has no type annotations.
 ignore_missing_imports = true
 
+[[tool.mypy.overrides]]
+module = 'incremental'
+# No released version with type hints.
+ignore_missing_imports = true
+
 
 [build-system]
 requires = [
@@ -86,7 +91,7 @@ branch = true
 source = ["towncrier"]
 
 [tool.coverage.paths]
-source = ["src", ".tox/*/site-packages"]
+source = ["src", ".nox/*/site-packages"]
 
 [tool.coverage.report]
 show_missing = true
diff --git a/setup.py b/setup.py
index 81a686aa..a55a7598 100644
--- a/setup.py
+++ b/setup.py
@@ -61,5 +61,4 @@
     description="Building newsfiles for your project.",
     long_description=open("README.rst").read(),
     entry_points={"console_scripts": ["towncrier = towncrier._shell:cli"]},
-    options={"bdist_wheel": {"universal": "1"}},
 )
diff --git a/src/towncrier/_project.py b/src/towncrier/_project.py
index 9c887ff0..ac40ddfd 100644
--- a/src/towncrier/_project.py
+++ b/src/towncrier/_project.py
@@ -12,6 +12,7 @@
 
 from importlib import import_module
 from types import ModuleType
+from typing import cast
 
 from incremental import Version
 
@@ -51,7 +52,7 @@ def get_version(package_dir: str, package: str) -> str:
         return version.strip()
 
     if isinstance(version, Version):
-        return version.base().strip()
+        return cast(str, version.base().strip())
 
     if isinstance(version, tuple):
         return ".".join(map(str, version)).strip()
@@ -78,6 +79,6 @@ def get_project_name(package_dir: str, package: str) -> str:
 
     if isinstance(version, Version):
         # Incremental has support for package names
-        return version.package
+        return cast(str, version.package)
 
     raise TypeError(f"Unsupported type for __version__: {type(version)}")
diff --git a/src/towncrier/newsfragments/430.misc b/src/towncrier/newsfragments/430.misc
new file mode 100644
index 00000000..a88a7a85
--- /dev/null
+++ b/src/towncrier/newsfragments/430.misc
@@ -0,0 +1,2 @@
+We now use `Nox <https://nox.thea.codes/>`_ instead of Tox.
+You may have to adjust a few command lines, but overall contributing should now be more comfortable.
diff --git a/src/towncrier/test/test_project.py b/src/towncrier/test/test_project.py
index 4d3531ce..0e55e068 100644
--- a/src/towncrier/test/test_project.py
+++ b/src/towncrier/test/test_project.py
@@ -5,12 +5,19 @@
 import sys
 
 from subprocess import check_output
+from unittest import skipIf
 
 from twisted.trial.unittest import TestCase
 
 from .._project import get_project_name, get_version
 
 
+try:
+    from importlib.metadata import version
+except ImportError:
+    version = None
+
+
 class VersionFetchingTests(TestCase):
     def test_str(self):
         """
@@ -40,6 +47,16 @@ def test_tuple(self):
         version = get_version(temp, "mytestproja")
         self.assertEqual(version, "1.3.12")
 
+    @skipIf(version is None, "Needs importlib.metadata.")
+    def test_incremental(self):
+        """
+        An incremental Version __version__  is picked up.
+        """
+        init = "../src/towncrier/__init__.py"
+
+        self.assertEqual(version("towncrier"), get_version(init, "towncrier"))
+        self.assertEqual("towncrier", get_project_name(init, "towncrier"))
+
     def test_unknown_type(self):
         """
         A __version__ of unknown type will lead to an exception.
diff --git a/tox.ini b/tox.ini
deleted file mode 100644
index 8f686157..00000000
--- a/tox.ini
+++ /dev/null
@@ -1,68 +0,0 @@
-[tox]
-envlist = pre-commit, {pypy37,pypy38,py37,py38,py39,py310,py311}-tests, check-manifest, check-newsfragment, typecheck
-isolated_build=true
-skip_missing_envs = true
-
-[testenv:pre-commit]
-skip_install = True
-deps = pre-commit
-commands =
-    pre-commit run --all-files --verbose
-
-[testenv:check-newsfragment]
-commands =
-   python -m towncrier.check --compare-with origin/trunk
-
-[testenv:check-manifest]
-deps = check-manifest
-skip_install = true
-commands = check-manifest
-
-[testenv]
-deps =
-   Twisted
-   coverage[toml]
-   incremental
-
-commands =
-   python -V
-   coverage --version
-   {envbindir}/trial --version
-   coverage erase
-   # `coverage run` tries to act like Python so we use `--module` instead of
-   # specifying the entry point script in `{envbindir}`.
-   coverage run -p --module twisted.trial {posargs:towncrier}
-   coverage combine -a
-   coverage report
-
-[testenv:typecheck]
-deps =
-   mypy
-   # 2022-09-04: There is no release yet which includes type annotations.
-   incremental @ git+https://github.com/twisted/incremental.git@5845557ab9
-   types-setuptools
-commands =
-   mypy src/
-
-[testenv:build]
-allowlist_externals =
-   bash
-changedir = {envtmpdir}
-deps =
-   build
-   check-manifest>=0.44
-   twine
-setenv =
-   toxinidir={toxinidir}
-skip_install = true
-commands =
-   # could be brought inside tox.ini after https://github.com/tox-dev/tox/issues/1571
-   bash {toxinidir}/tox_build.sh
-
-[testenv:docs]
-extras = dev
-# I have no idea why the previous `extra = dev` doesn't install sphinx via tox.
-deps = sphinx >= 5
-commands =
-   # This tries to be as close as possible to the command used by Read The Docs.
-   python -m sphinx -T -E -W --keep-going -b html -d docs/_build/doctrees -D language=en docs docs/_build/html
diff --git a/tox_build.sh b/tox_build.sh
deleted file mode 100644
index c43685f3..00000000
--- a/tox_build.sh
+++ /dev/null
@@ -1,16 +0,0 @@
-# build the sdist
-
-set -evx
-
-check-manifest --verbose ${toxinidir}
-
-python -m build --sdist --outdir ${toxinidir}/dist/ ${toxinidir}
-
-tar -xvf ${toxinidir}/dist/*
-cd *
-
-# build the wheel from the sdist
-python -m build --wheel --outdir ${toxinidir}/dist/ .
-cd -
-
-twine check ${toxinidir}/dist/*