Update python setup.py version safely

version.py

import ast
import jedi
from os import path
from pipenv.project import Project
from git import Repo
from git.refs.tag import TagReference
from pkg_resources import get_distribution

class Semver:

    def __init__(self, string):
        major, minor, patch = map(int, string.split('.'))
        self.major = major
        self.minor = minor
        self.patch = patch

    def __str__(self):
        return '.'.join(map(str, (self.major, self.minor, self.patch)))
    
    def add(self, part, amount):
        setattr(self, part, getattr(self, part) + amount)
        return self

def is_setup(source, call):
    script = jedi.api.Script(source, call.lineno, call.col_offset)
    definition = script.goto_definitions()[-1]
    return definition.module_name == 'core' and definition.name == 'setup'

def replace_in_line(line, old, new, string):
    lines = string.split('\n')
    lines[line] = lines[line].replace(old, new)
    return '\n'.join(lines)

def get_setup_version_value_node(source):
    for node in ast.walk(ast.parse(source)):
        if isinstance(node, ast.Call) and is_setup(source, node):
            for keyword in node.keywords:
                if keyword.arg == 'version':
                    return keyword.value

project = Project()

def update_setup_file_version(part, setup_path):
    with open(setup_path, 'r+') as setup:
        source = setup.read()
        value = get_setup_version_value_node(source)
        old_version = value.s
        new_version = str(Semver(old_version).add(part, 1))
        setup.seek(0)
        setup.write(replace_in_line(value.lineno - 1, old_version, new_version, source))
        setup.truncate()
        return new_version

# part = 'major' | 'minor' | 'patch'
def version(part):
    setup_path = path.join(project.project_directory, 'setup.py')
    if not path.exists(setup_path):
        raise NotImplementedError('setup.py must exist')
    new_version = update_setup_file_version(part, setup_path)
    repo = Repo(project.project_directory)
    repo.index.add(['setup.py'])
    repo.index.commit(f'v{new_version}')
    repo.create_tag(f'v{new_version}', ref=repo.active_branch)
    return new_version
        

if __name__ == "__main__":
  import sys
  new_version = version(sys.argv[1])
  print(new_version)

requires pipenv and GitPython installed (pip install pipenv GitPython)
usage: python3 version.py patch | minor | major