List runtime dependencies in pyproject toml

We could include requirements.txt as well but that requires more complex
parsing as we would need to resolve `-r some_other_file.txt` and similar
[1].

[1] https://pip.pypa.io/en/stable/reference/requirements-file-format/

Author: lagru

README.md

@@ -11,6 +11,7 @@ https://github.com/scientific-python/changelist/blob/main/CHANGELOG.md.
 - Categorize pull requests into sections based on GitHub labels.
 - Point it at any repository on GitHub. No need to clone or checkout a
   repository locally, a Python package is all that's needed.
+- List latest runtime dependencies of your release.
 
 We recommend to treat the generated document as a first draft to build
 on and not as an already perfect documentation of the release.

src/changelist/_cli.py

@@ -11,9 +11,9 @@
 from github import Github
 from tqdm import tqdm
 
+from . import _query
 from ._config import add_config_defaults, local_config, remote_config
 from ._format import MdFormatter, RstFormatter
-from ._query import commits_between, contributors, pull_requests_from_commits
 
 logger = logging.getLogger(__name__)
 
@@ -141,23 +141,27 @@ def main(
     config = add_config_defaults(config)
 
     print("Fetching commits...", file=sys.stderr)
-    commits = commits_between(gh, org_repo, start_rev, stop_rev)
-    pull_requests = pull_requests_from_commits(
+    commits = _query.commits_between(gh, org_repo, start_rev, stop_rev)
+    pull_requests = _query.pull_requests_from_commits(
         lazy_tqdm(commits, desc="Fetching pull requests")
     )
-    authors, reviewers = contributors(
+    authors, reviewers = _query.contributors(
         gh=gh,
         org_repo=org_repo,
         commits=lazy_tqdm(commits, desc="Fetching authors"),
         pull_requests=lazy_tqdm(pull_requests, desc="Fetching reviewers"),
     )
+    runtime_dependencies = _query.pyproject_dependencies(
+        gh=gh, org_repo=org_repo, rev=stop_rev
+    )
 
     Formatter = {"md": MdFormatter, "rst": RstFormatter}[format]
     formatter = Formatter(
         repo_name=org_repo.split("/")[-1],
         pull_requests=pull_requests,
         authors=authors,
         reviewers=reviewers,
+        runtime_dependencies=runtime_dependencies,
         version=version,
         title_template=config["title_template"],
         intro_template=config["intro_template"],

src/changelist/_format.py

@@ -19,6 +19,7 @@ class MdFormatter:
     pull_requests: set[PullRequest]
     authors: set[Union[NamedUser]]
     reviewers: set[NamedUser]
+    runtime_dependencies: set[str]
 
     version: str
     title_template: str
@@ -52,6 +53,8 @@ def iter_lines(self) -> Iterable[str]:
         yield from self._format_intro()
         for title, pull_requests in self._prs_by_section.items():
             yield from self._format_pr_section(title, pull_requests)
+        if self.runtime_dependencies:
+            yield from self._format_dependencies_section(self.runtime_dependencies)
         yield from self._format_contributor_section(self.authors, self.reviewers)
         yield from self._format_outro()
 
@@ -158,6 +161,17 @@ def _format_contributor_section(
         yield from sorted(reviewers_lines, key=lambda s: s.lower())
         yield "\n"
 
+    def _format_dependencies_section(self, runtime_dependencies: set[str]):
+        yield from self._format_section_title("Dependencies", level=2)
+        yield "\n"
+        yield "Minimal runtime dependencies:\n"
+        yield "\n"
+        for dependency in sorted(runtime_dependencies):
+            line = f"`{dependency}`"
+            line = self._sanitize_text(line)
+            yield f"- {line}\n"
+        yield "\n"
+
     def _format_intro(self):
         intro = self.intro_template.format(
             repo_name=self.repo_name, version=self.version

src/changelist/_query.py

@@ -5,11 +5,17 @@
 from dataclasses import dataclass
 
 import requests
-from github import Github
+from github import Github, UnknownObjectException
 from github.Commit import Commit
 from github.NamedUser import NamedUser
 from github.PullRequest import PullRequest
 
+try:
+    import tomllib
+except ModuleNotFoundError:
+    import tomli as tomllib
+
+
 logger = logging.getLogger(__name__)
 
 
@@ -174,3 +180,27 @@ def contributors(
                 reviewers.add(review.user)
 
     return authors, reviewers
+
+
+def pyproject_dependencies(
+    gh: Github,
+    org_repo: str,
+    rev: str,
+):
+    """Fetch runtime dependencies from pyproject.toml at the given revision."""
+    repo = gh.get_repo(org_repo)
+    try:
+        file = repo.get_contents("pyproject.toml", ref=rev)
+        logger.debug("found pyproject.toml in %s@%s", org_repo, rev)
+        content = file.decoded_content.decode()
+    except UnknownObjectException:
+        content = ""
+    pyproject = tomllib.loads(content)
+
+    runtime_dependencies = []
+    python_dep = pyproject.get("project", {}).get("requires-python")
+    if python_dep:
+        runtime_dependencies += [f"python{python_dep}"]
+    runtime_dependencies += pyproject.get("project", {}).get("dependencies", [])
+
+    return runtime_dependencies