Automate release preparation

scripts/prepare_release.py

@@ -24,6 +24,13 @@
 VERSION_RE = re.compile(r"[0-9]+(?:\.[0-9]+)+(?:[a-zA-Z0-9_.+-]+)?")
 _CHANGELOG_HEADING_RE = re.compile(r"^## \[(?P<version>[^\]]+)\](?:\s+-\s+.*)?\s*$")
 _CHANGELOG_SUBHEADING_RE = re.compile(r"^### (?P<header>.+?)\s*$")
+_RELEASE_FILES = (
+    "CHANGELOG.md",
+    "pyproject.toml",
+    "temporalio/service.py",
+    "uv.lock",
+)
+_RELEASE_FILE_SET = frozenset(_RELEASE_FILES)
 
 
 def validate_version(version: str) -> str:
@@ -94,6 +101,82 @@ def replace_service_version(text: str, version: str) -> str:
     )
 
 
+def create_release_branch(repo_root: pathlib.Path, version: str) -> None:
+    subprocess.run(["git", "fetch", "origin", "main"], cwd=repo_root, check=True)
+    subprocess.run(
+        ["git", "switch", "--create", f"chore/release-{version}", "origin/main"],
+        cwd=repo_root,
+        check=True,
+    )
+
+
+def changed_files(repo_root: pathlib.Path) -> set[str]:
+    result = subprocess.run(
+        ["git", "status", "--porcelain"],
+        cwd=repo_root,
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    return {line[3:] for line in result.stdout.splitlines()}
+
+
+def ensure_clean_worktree(repo_root: pathlib.Path) -> None:
+    changes = changed_files(repo_root)
+    if changes:
+        raise RuntimeError(
+            "Release preparation requires a clean worktree; found changes in "
+            + ", ".join(sorted(changes))
+        )
+
+
+def ensure_only_release_changes(repo_root: pathlib.Path) -> None:
+    unexpected_files = changed_files(repo_root) - _RELEASE_FILE_SET
+    if unexpected_files:
+        raise RuntimeError(
+            "Release preparation changed unexpected files: "
+            + ", ".join(sorted(unexpected_files))
+        )
+
+
+def commit_release_changes(repo_root: pathlib.Path, version: str) -> None:
+    subprocess.run(
+        ["git", "commit", "-m", f"Prepare release {version}", "--", *_RELEASE_FILES],
+        cwd=repo_root,
+        check=True,
+    )
+
+
+def push_release_branch(repo_root: pathlib.Path, version: str) -> None:
+    branch = f"chore/release-{version}"
+    subprocess.run(
+        ["git", "push", "--set-upstream", "origin", branch],
+        cwd=repo_root,
+        check=True,
+    )
+
+
+def create_release_pr(repo_root: pathlib.Path, version: str) -> None:
+    branch = f"chore/release-{version}"
+    subprocess.run(
+        [
+            "gh",
+            "pr",
+            "create",
+            "--base",
+            "main",
+            "--head",
+            branch,
+            "--title",
+            f"Prepare release {version}",
+            "--body",
+            f"Prepare release {version}.",
+        ],
+        cwd=repo_root,
+        check=True,
+    )
+
+
 def _seeded_unreleased_lines() -> list[str]:
     lines = ["## [Unreleased]", ""]
     for header in CHANGELOG_HEADERS:
@@ -197,6 +280,8 @@ def main(argv: Sequence[str] | None = None) -> None:
     repo_root = pathlib.Path(__file__).resolve().parents[1]
     version = validate_version(args.version)
     release_date = parse_date(args.date)
+    ensure_clean_worktree(repo_root)
+    create_release_branch(repo_root, version)
     changelog_path = repo_root / "CHANGELOG.md"
     pyproject_path = repo_root / "pyproject.toml"
     service_path = repo_root / "temporalio" / "service.py"
@@ -228,7 +313,14 @@ def main(argv: Sequence[str] | None = None) -> None:
     if not args.skip_lock:
         subprocess.run(["uv", "lock"], cwd=repo_root, check=True)
 
-    print(f"Prepared release {version} dated {release_date.isoformat()}")
+    ensure_only_release_changes(repo_root)
+    commit_release_changes(repo_root, version)
+    push_release_branch(repo_root, version)
+    create_release_pr(repo_root, version)
+
+    print(
+        f"Prepared release {version} dated {release_date.isoformat()} and opened a PR"
+    )
 
 
 if __name__ == "__main__":

tests/test_prepare_release.py

@@ -1,9 +1,18 @@
 from __future__ import annotations
 
 import datetime
+import pathlib
+import subprocess
+
+import pytest
 
 from scripts.prepare_release import (
+    create_release_branch,
+    create_release_pr,
+    ensure_clean_worktree,
+    ensure_only_release_changes,
     finalize_changelog_release,
+    push_release_branch,
     replace_project_version,
     replace_service_version,
 )
@@ -80,3 +89,112 @@ def test_replace_versions() -> None:
         )
         == '__version__ = "1.30.0"\n\nServiceRequest = TypeVar("ServiceRequest")'
     )
+
+
+def test_create_release_branch_fetches_main_and_branches_from_it(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    calls: list[tuple[list[str], pathlib.Path, bool]] = []
+
+    def run(command: list[str], *, cwd: pathlib.Path, check: bool) -> None:
+        calls.append((command, cwd, check))
+
+    monkeypatch.setattr(subprocess, "run", run)
+
+    repo_root = pathlib.Path("/repo")
+    create_release_branch(repo_root, "1.30.0")
+
+    assert calls == [
+        (["git", "fetch", "origin", "main"], repo_root, True),
+        (
+            ["git", "switch", "--create", "chore/release-1.30.0", "origin/main"],
+            repo_root,
+            True,
+        ),
+    ]
+
+
+def test_ensure_clean_worktree_rejects_existing_changes(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(
+        subprocess,
+        "run",
+        lambda *_args, **_kwargs: subprocess.CompletedProcess(
+            args=[], returncode=0, stdout=" M temporalio/service.py\n"
+        ),
+    )
+
+    with pytest.raises(RuntimeError, match="clean worktree"):
+        ensure_clean_worktree(pathlib.Path("/repo"))
+
+
+def test_ensure_only_release_changes_rejects_unexpected_files(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(
+        subprocess,
+        "run",
+        lambda *_args, **_kwargs: subprocess.CompletedProcess(
+            args=[], returncode=0, stdout=" M unrelated.txt\n"
+        ),
+    )
+
+    with pytest.raises(RuntimeError, match="unexpected files: unrelated.txt"):
+        ensure_only_release_changes(pathlib.Path("/repo"))
+
+
+def test_create_release_pr_uses_versioned_branch(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    calls: list[tuple[list[str], pathlib.Path, bool]] = []
+
+    def run(command: list[str], *, cwd: pathlib.Path, check: bool) -> None:
+        calls.append((command, cwd, check))
+
+    monkeypatch.setattr(subprocess, "run", run)
+
+    repo_root = pathlib.Path("/repo")
+    create_release_pr(repo_root, "1.30.0")
+
+    assert calls == [
+        (
+            [
+                "gh",
+                "pr",
+                "create",
+                "--base",
+                "main",
+                "--head",
+                "chore/release-1.30.0",
+                "--title",
+                "Prepare release 1.30.0",
+                "--body",
+                "Prepare release 1.30.0.",
+            ],
+            repo_root,
+            True,
+        )
+    ]
+
+
+def test_push_release_branch_uses_versioned_branch(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    calls: list[tuple[list[str], pathlib.Path, bool]] = []
+
+    def run(command: list[str], *, cwd: pathlib.Path, check: bool) -> None:
+        calls.append((command, cwd, check))
+
+    monkeypatch.setattr(subprocess, "run", run)
+
+    repo_root = pathlib.Path("/repo")
+    push_release_branch(repo_root, "1.30.0")
+
+    assert calls == [
+        (
+            ["git", "push", "--set-upstream", "origin", "chore/release-1.30.0"],
+            repo_root,
+            True,
+        )
+    ]