---
title: Bump version numbers when releasing
author: Lars Wirzenius
version: git version
...


# Introduction

Bumper is a small utility for updating version numbers when making a
release of a software project. It updates the version number in the
various locations in which it is stored in the source tree, creates a
git tag for indicating the release, then updates the source tree again
with a version number that indicates an unreleased version.

# Assumptions about the source tree

Bumper makes several assumptions about the source tree, to keep things
simpler. Here's a list:

* The source tree is stored in git. No other version control systems
  are supported, sorry, but that's just because git is the only thing
  the author uses now.

* The project is in Python. Again, this is just because that's what
  the author uses.

* The project contains exactly one file called `version.py`, and that
  file only sets the variables `__version__` and `__version_info__`.
  Bumper will overwrite that file so it sets the desired values, and
  commits those changes to git.

* `setup.py` is assumed to get the version from `__version__` from the
  file Bumper writes, in some suitable way. Likewise the rest of the
  project.

* It's OK for Bumper to make several commits and a tag in the git
  repository.


# Using Bumper

In the examples below, we'll use Bumper on a fairly typical Python
project called `foo`, and we'll make a release 3.2 of it.

    SCENARIO release a project

We will use a PGP test key for signing tags.

    GIVEN a PGP key with id AA8CD13C

The Foo project consists of a main program, which uses a little Python
package where all the real code is, and where the version number is
also stored.

    GIVEN Python project foo, version controlled by git
    AND a file foolib/version.py in foo containing 
    ... "__version__ = '1.0'\n__version_info__ = (1, 0)\n"
    AND project foo has Debian packaging

We run Bumper to update version numbers and tag a new release. We
first try with a version that's older than the current one.

    WHEN user attempts to run "bumper 0.1" in the foo directory
    THEN bumper exits with code 1

We now run Bumper properly, and it does its various things.

    WHEN user runs "bumper 3.2" in the foo directory

Bumper creates a git tag for the release, and updates files in the tag
to have the right version number.

    THEN git repository foo has tag foo-3.2, signed with AA8CD13C
    AND in foo, tag foo-3.2, foolib/version.py contains
    ... "__version__ = "3.2"\n__version_info__ = (3, 2)\n"
    AND in foo, tag foo-3.2, NEWS matches
    ... "^Version 3.2, released \\d\\d\\d\\d-\\d\\d-\\d\\d$"
    AND in foo, tag foo-3.2, has Debian version 3.2-1

Further, Bumper updates the files in master to have a version number
with `+git` appended, so that any non-release builds (builds not from
the tag) won't report a version number that looks like a release.

    AND file foolib/version.py in foo contains
    ... "__version__ = "3.2+git"\n__version_info__ = (3, 2, '+git')\n"
    AND file debian/changelog in foo matches
    ... "foo \\(3\\.2\\+git-1\\) UNRELEASED;"
    AND file NEWS in foo matches
    ... "Version 3\\.2\\+git, not yet released"

We can also make a second release.

    WHEN user runs "bumper 3.4" in the foo directory
    THEN git repository foo has tag foo-3.4, signed with AA8CD13C
    AND in foo, tag foo-3.4, foolib/version.py contains
    ... "__version__ = "3.4"\n__version_info__ = (3, 4)\n"
    AND in foo, tag foo-3.4, NEWS matches
    ... "^Version 3.4, released \\d\\d\\d\\d-\\d\\d-\\d\\d$"
    AND in foo, tag foo-3.4, has Debian version 3.4-1
    AND file foolib/version.py in foo contains
    ... "__version__ = "3.4+git"\n__version_info__ = (3, 4, '+git')\n"
    AND file debian/changelog in foo matches
    ... "foo \\(3\\.4\\+git-1\\) UNRELEASED;"
    AND file NEWS in foo matches
    ... "Version 3\\.4\\+git, not yet released"

# Appendix: Scenario step implementations

This chapter provides executable implementations of the various
scenario steps, making this manual an automated [yarn][] test suite
for Bumper.

[yarn]: http://liw.fi/cmdtest/

    IMPLEMENTS GIVEN a PGP key with id (\S+)
    import os, shutil, cliapp, yarnstep
    keyid = yarnstep.get_next_match()
    src = yarnstep.srcdir('dot-gnupg')
    dst = yarnstep.datadir('HOME/.gnupg')
    shutil.copytree(src, dst)
    cliapp.runcmd(
        ['gpg', '--list-keys', keyid],
        cwd=os.environ['HOME'])
    # Configure git to use this key for signing.
    cliapp.runcmd(['git', 'config', '--global', 'user.signingkey', keyid])

    IMPLEMENTS GIVEN Python project (\S+), version controlled by git
    import os, cliapp, yarnstep
    project = yarnstep.get_next_match()
    dirname = yarnstep.datadir(project)
    yarnstep.write_file(os.path.join(dirname, 'foolib', '__init__.py'), '''
    from .version import __version__, __version_info__
    ''')
    yarnstep.write_file(os.path.join(dirname, 'setup.py'), '''
    from distutils.core import setup
    import foolib
    setup(name='{project}', version=foolib.__version__)
    '''.format(project=project))
    yarnstep.write_file(os.path.join(dirname, 'NEWS'), '''
    NEWS for {project}
    ==================
    Version 0.0, not yet released
    -----------------------------
    '''.format(project=project))
    cliapp.runcmd(['git', 'init', dirname])
    cliapp.runcmd(['git', 'add', '.'], cwd=dirname)
    cliapp.runcmd(['git', 'commit', '-mInitial'], cwd=dirname)

    IMPLEMENTS GIVEN a file (\S+) in (\S+) containing "(.*)"
    import os, cliapp, yarnstep
    filename = yarnstep.get_next_match()
    dirname = yarnstep.get_next_match_as_datadir_path()
    data = yarnstep.get_next_match()
    yarnstep.write_file(
        os.path.join(dirname, filename),
        yarnstep.unescape_backslashes(data))
    cliapp.runcmd(['git', 'add', filename], cwd=dirname)
    cliapp.runcmd(
        ['git', 'commit', '-m', 'Add {}'.format(filename)],
        cwd=dirname)

    IMPLEMENTS GIVEN project (\S+) has Debian packaging
    import os, cliapp, yarnstep
    project = yarnstep.get_next_match()
    dirname = yarnstep.datadir(project)
    os.mkdir(os.path.join(dirname, 'debian'))
    cliapp.runcmd(
        ['dch', '--create', '-v', '1.0-1', '--package', project, ''],
        cwd=dirname)
    cliapp.runcmd(['git', 'add', 'debian'], cwd=dirname)
    cliapp.runcmd(['git', 'commit', '-m', 'Add debian packaging'], cwd=dirname)

    IMPLEMENTS WHEN user attempts to run "bumper (\S+)" in the (\S+) directory
    import cliapp, yarnstep
    version = yarnstep.get_next_match()
    dirname = yarnstep.get_next_match_as_datadir_path()
    bin = yarnstep.srcdir('bumper')
    returncode, out, err = cliapp.runcmd_unchecked([bin, version], cwd=dirname)
    yarnstep.write_file(yarnstep.datadir('bumper.exit'), str(returncode))

    IMPLEMENTS THEN bumper exits with code (\d+)
    import yarnstep
    expected = yarnstep.get_next_match()
    actual = yarnstep.cat(yarnstep.datadir('bumper.exit'))
    print 'expected:', repr(expected)
    print 'actual:', repr(actual)
    assert expected == actual

    IMPLEMENTS WHEN user runs "bumper (\S+)" in the (\S+) directory
    import cliapp, yarnstep
    version = yarnstep.get_next_match()
    dirname = yarnstep.get_next_match_as_datadir_path()
    bin = yarnstep.srcdir('bumper')
    cliapp.runcmd([bin, version], cwd=dirname)

    IMPLEMENTS THEN file (\S+) in (\S+) contains "(.*)"
    import os, yarnstep
    filename = yarnstep.get_next_match()
    dirname = yarnstep.get_next_match_as_datadir_path()
    wanted_data_escaped = yarnstep.get_next_match()
    wanted_data = yarnstep.unescape_backslashes(wanted_data_escaped)
    actual_data = yarnstep.cat(os.path.join(dirname, filename))
    print 'wanted_data:', repr(wanted_data)
    print 'actual_data:', repr(actual_data)
    assert wanted_data == actual_data

    IMPLEMENTS THEN file (\S+) in (\S+) matches "(.*)"
    import re, os, yarnstep
    filename = yarnstep.get_next_match()
    dirname = yarnstep.get_next_match_as_datadir_path()
    wanted_data_escaped = yarnstep.get_next_match()
    wanted_data = yarnstep.unescape_backslashes(wanted_data_escaped)
    actual_data = yarnstep.cat(os.path.join(dirname, filename))
    print 'wanted_data:', repr(wanted_data)
    print 'actual_data:', repr(actual_data)
    assert re.search(wanted_data, actual_data)

    IMPLEMENTS THEN in (\S+), tag (\S+), (\S+) contains "(.*)"
    import cliapp, yarnstep
    dirname = yarnstep.get_next_match_as_datadir_path()
    tag = yarnstep.get_next_match()
    filename = yarnstep.get_next_match()
    wanted_data_escaped = yarnstep.get_next_match()
    wanted_data = yarnstep.unescape_backslashes(wanted_data_escaped)
    actual_data = cliapp.runcmd(
        ['git', 'cat-file', 'blob', '{}:{}'.format(tag, filename)],
        cwd=dirname)
    print 'wanted_data:', repr(wanted_data)
    print 'actual_data:', repr(actual_data)
    assert wanted_data == actual_data

    IMPLEMENTS THEN in (\S+), tag (\S+), (\S+) matches "(.*)"
    import re, cliapp, yarnstep
    dirname = yarnstep.get_next_match_as_datadir_path()
    tag = yarnstep.get_next_match()
    filename = yarnstep.get_next_match()
    wanted_data_escaped = yarnstep.get_next_match()
    wanted_data = yarnstep.unescape_backslashes(wanted_data_escaped)
    actual_data = cliapp.runcmd(
        ['git', 'cat-file', 'blob', '{}:{}'.format(tag, filename)],
        cwd=dirname)
    print 'wanted_data:', repr(wanted_data)
    print 'actual_data:', repr(actual_data)
    assert re.search(wanted_data, actual_data, flags=re.M)

    IMPLEMENTS THEN in (\S+), tag (\S+), has Debian version (\S+)
    import os, cliapp, yarnstep
    dirname = yarnstep.get_next_match_as_datadir_path()
    tag = yarnstep.get_next_match()
    version = yarnstep.get_next_match()
    text = cliapp.runcmd(
        ['git', 'cat-file', 'blob', '{}:debian/changelog'.format(tag)],
        cwd=dirname)
    line1, _ = text.split('\n', 1)
    print 'line1:', repr(line1)
    assert '({})'.format(version) in line1
    assert line1.split()[2] != 'UNRELEASED;'

    IMPLEMENTS THEN git repository (\S+) has tag (\S+), signed with (\S+)
    import subprocess, cliapp, yarnstep
    dirname = yarnstep.get_next_match_as_datadir_path()
    tagname = yarnstep.get_next_match()
    keyid = yarnstep.get_next_match()
    output = cliapp.runcmd(
        ['git', 'verify-tag', tagname],
        cwd=dirname,
        stderr=subprocess.STDOUT)
    assert keyid in output