How to Mock a semantic-release Changelog in Python

import json
from datetime import datetime


class SemanticReleaseChangelog:
    def __init__(self, version, commits):
        self.version = version
        self.commits = commits
        self.release_date = datetime.now().isoformat()

    def generate_changelog(self):
        grouped = {}
        for commit in self.commits:
            type_name = commit["type"]
            if type_name not in grouped:
                grouped[type_name] = []
            grouped[type_name].append(commit["message"])

        sections = []
        for type_name, messages in grouped.items():
            section = f"### {type_name.capitalize()}\n"
            section += "\n".join(f"- {msg}" for msg in messages)
            sections.append(section)

        changelog = (
            f"## v{self.version} ({self.release_date[:10]})\n\n"
            + "\n\n".join(sections)
            + "\n"
        )
        return changelog


if __name__ == "__main__":
    mock_commits = [
        {"type": "feat", "message": "add new API endpoint"},
        {"type": "fix", "message": "resolve memory leak"},
        {"type": "feat", "message": "implement dark mode"},
        {"type": "docs", "message": "update readme"},
    ]
    cl = SemanticReleaseChangelog("1.4.0", mock_commits)
    output = cl.generate_changelog()
    print(output)