Replace playbook with code for finalizing a release.

docs/releases.txt

@@ -3,39 +3,13 @@ Release Process
 ===============
 
 In order to allow for rapid, predictable releases, Setuptools uses a
-mechanical technique for releases, enacted by Travis following a
-successful build of a tagged release per
-`PyPI deployment <https://docs.travis-ci.com/user/deployment/pypi>`_.
-
-Prior to cutting a release, please use `towncrier`_ to update
-``CHANGES.rst`` to summarize the changes since the last release.
-To update the changelog:
-
-1. Install towncrier via ``pip install towncrier`` if not already installed.
-2. Preview the new ``CHANGES.rst`` entry by running
-   ``towncrier --draft --version {new.version.number}`` (enter the desired
-   version number for the next release).  If any changes are needed, make
-   them and generate a new preview until the output is acceptable.  Run
-   ``git add`` for any modified files.
-3. Run ``towncrier --version {new.version.number}`` to stage the changelog
-   updates in git.
-4. Verify that there are no remaining ``changelog.d/*.rst`` files.  If a
-   file was named incorrectly, it may be ignored by towncrier.
-5. Review the updated ``CHANGES.rst`` file.  If any changes are needed,
-   make the edits and stage them via ``git add CHANGES.rst``.
-
-Once the changelog edits are staged and ready to commit, cut a release by
-installing and running ``bump2version --allow-dirty {part}`` where ``part``
-is major, minor, or patch based on the scope of the changes in the
-release. Then, push the commits to the master branch::
-
-    $ git push origin master
-    $ git push --tags
-
-If tests pass, the release will be uploaded to PyPI (from the Python 3.6
-tests).
-
-.. _towncrier: https://pypi.org/project/towncrier/
+mechanical technique for releases, enacted on tagged commits by
+continuous integration.
+
+To finalize a release, run ``tox -e finalize``, review, then push
+the changes.
+
+If tests pass, the release will be uploaded to PyPI.
 
 Release Frequency
 -----------------

tools/finalize.py

+"""
+Finalize the repo for a release. Invokes towncrier and bumpversion.
+"""
+
+__requires__ = ['bump2version', 'towncrier']
+
+
+import subprocess
+import pathlib
+import re
+import sys
+
+
+def release_kind():
+    """
+    Determine which release to make based on the files in the
+    changelog.
+    """
+    # use min here as 'major' < 'minor' < 'patch'
+    return min(
+        'major' if 'breaking' in file.name else
+        'minor' if 'change' in file.name else
+        'patch'
+        for file in pathlib.Path('changelog.d').iterdir()
+    )
+
+
+bump_version_command = [
+    sys.executable,
+    '-m', 'bumpversion',
+    release_kind(),
+]
+
+
+def get_version():
+    cmd = bump_version_command + ['--dry-run', '--verbose']
+    out = subprocess.check_output(cmd, text=True)
+    return re.search('^new_version=(.*)', out, re.MULTILINE).group(1)
+
+
+def update_changelog():
+    cmd = [
+        sys.executable, '-m',
+        'towncrier',
+        '--version', get_version(),
+        '--yes',
+    ]
+    subprocess.check_call(cmd)
+
+
+def bump_version():
+    cmd = bump_version_command + ['--allow-dirty']
+    subprocess.check_call(cmd)
+
+
+if __name__ == '__main__':
+    print("Cutting release at", get_version())
+    update_changelog()
+    bump_version()

tox.ini

@@ -58,6 +58,13 @@ source=
 omit=
 	*/_vendor/*
 
+[testenv:finalize]
+deps =
+	towncrier
+	bump2version
+commands =
+	python tools/finalize.py
+
 [testenv:release]
 skip_install = True
 deps =