Comment changeset status in PRs (#625)

* Initial implementation * Fix * fix * fix * Make it look nicer * Update docs * Rename to pr-status-comment * Remove outputs * Update path * update name * Checkout PR in a detached worktree (#626) Co-authored-by: bluwy <bjornlu.dev@gmail.com> * Move comment to separate job * Loosen event requirement * Update * Apply suggestions from code review Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com> * Use TLA * use using * Remove test log --------- Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>
2026-10-26 16:39:56 +08:00 · 2026-05-29 12:27:24 +00:00
parent 34f64f6e2e
commit 8795eee5ee
12 changed files with 599 additions and 2 deletions
@@ -0,0 +1,165 @@
+import { randomUUID } from "node:crypto";
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import type * as github from "@actions/github";
+import { isRepoShallow } from "@changesets/git";
+import { exec } from "tinyexec";
+
+type PullRequestContext = NonNullable<
+  typeof github.context.payload.pull_request
+>;
+
+type WorktreeInfo = {
+  baseRef: string;
+  cwd: string;
+};
+
+type TinyexecOptions = Parameters<typeof exec>[2];
+
+function git(cwd: string, args: string[], opts: TinyexecOptions = {}) {
+  return exec("git", args, {
+    nodeOptions: { cwd, ...opts.nodeOptions },
+    throwOnError: true,
+    ...opts,
+  });
+}
+
+interface Ref {
+  fetchSource: string;
+  local: string;
+  remote: string;
+}
+
+function getRefs(context: PullRequestContext): Record<"base" | "head", Ref> {
+  const suffix = `${context.number}-${randomUUID()}`;
+  return {
+    base: {
+      fetchSource: "origin",
+      local: `refs/changesets-action-pr-status/base/${suffix}`,
+      remote: `refs/heads/${context.base.ref}`,
+    },
+    head: {
+      fetchSource: context.head.repo.clone_url,
+      local: `refs/changesets-action-pr-status/head/${suffix}`,
+      remote: `refs/heads/${context.head.ref}`,
+    },
+  };
+}
+
+async function deepenRef(cwd: string, ref: Ref, deepenBy: number) {
+  await git(cwd, [
+    "fetch",
+    "--no-tags",
+    `--deepen=${deepenBy}`,
+    ref.fetchSource,
+    `${ref.remote}:${ref.local}`,
+  ]);
+}
+
+async function ensureMergeBase(args: {
+  cwd: string;
+  refs: ReturnType<typeof getRefs>;
+  deepenBy?: number;
+}) {
+  const { cwd, refs, deepenBy = 50 } = args;
+
+  while (true) {
+    const mergeBase = await git(cwd, ["merge-base", refs.base.local, "HEAD"], {
+      throwOnError: false,
+    });
+
+    if (mergeBase.exitCode === 0) {
+      return mergeBase.stdout.trim();
+    }
+
+    if (!(await isRepoShallow({ cwd }))) {
+      throw new Error(
+        `Failed to find merge base between "${refs.base.local}" and HEAD, and the repository is no longer shallow.`,
+      );
+    }
+
+    await deepenRef(cwd, refs.base, deepenBy);
+    await deepenRef(cwd, refs.head, deepenBy);
+  }
+}
+
+async function mkdtemp(prefix: string) {
+  const dir = await fs.mkdtemp(path.join(os.tmpdir(), prefix));
+
+  return {
+    dir,
+    async [Symbol.asyncDispose]() {
+      await fs.rm(dir, { recursive: true, force: true });
+    },
+  };
+}
+
+async function tempRef(cwd: string, ref: Ref) {
+  await git(cwd, [
+    "fetch",
+    "--no-tags",
+    "--depth=1",
+    ref.fetchSource,
+    `${ref.remote}:${ref.local}`,
+  ]);
+  return {
+    async [Symbol.asyncDispose]() {
+      await git(cwd, ["update-ref", "-d", ref.local], { throwOnError: false });
+    },
+  };
+}
+
+async function tempWorktree(cwd: string, dir: string, ref: Ref) {
+  await git(cwd, ["worktree", "add", "--detach", dir, ref.local]);
+
+  return {
+    async [Symbol.asyncDispose]() {
+      await git(cwd, ["worktree", "remove", "--force", dir], {
+        throwOnError: false,
+      });
+    },
+  };
+}
+
+type WithAsyncDispose<T> = T & {
+  [Symbol.asyncDispose](): Promise<void>;
+};
+
+function moveDisposable<T extends object>(
+  stack: AsyncDisposableStack,
+  value: T,
+): WithAsyncDispose<T> {
+  const moved = stack.move();
+  return Object.assign(value, {
+    async [Symbol.asyncDispose]() {
+      await moved.disposeAsync();
+    },
+  });
+}
+
+export async function getPullRequestWorktree(
+  context: PullRequestContext,
+  cwd: string = process.cwd(),
+): Promise<WithAsyncDispose<WorktreeInfo>> {
+  await using stack = new AsyncDisposableStack();
+  const worktreeDir = stack.use(
+    await mkdtemp("changesets-action-pr-status-"),
+  ).dir;
+
+  const refs = getRefs(context);
+
+  stack.use(await tempRef(cwd, refs.base));
+  stack.use(await tempRef(cwd, refs.head));
+  stack.use(await tempWorktree(cwd, worktreeDir, refs.head));
+
+  await ensureMergeBase({
+    cwd: worktreeDir,
+    refs,
+  });
+
+  return moveDisposable(stack, {
+    baseRef: refs.base.local,
+    cwd: worktreeDir,
+  });
+}