fix(release): draft the changelog from a freshly fetched origin/main

scripts/draft-changelog.test.ts

@@ -1,4 +1,8 @@
 import assert from "node:assert/strict";
+import { execFileSync } from "node:child_process";
+import { cpSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
 import { describe, it } from "node:test";
 import {
   escapeForMdx,
@@ -195,3 +199,60 @@ describe("release tags", () => {
     assert.deepEqual(renderTags(commits), ["Release", "Core"]);
   });
 });
+
+describe("drafting from a checkout that is behind", () => {
+  const git = (cwd: string, ...args: string[]) =>
+    execFileSync(
+      "git",
+      [
+        "-c",
+        "user.name=t",
+        "-c",
+        "user.email=t@t",
+        "-c",
+        "tag.gpgSign=false",
+        "-c",
+        "commit.gpgSign=false",
+        ...args,
+      ],
+      {
+        cwd,
+        encoding: "utf-8",
+      },
+    ).trim();
+  const land = (cwd: string, subject: string) => {
+    writeFileSync(join(cwd, "file.txt"), subject);
+    git(cwd, "add", ".");
+    git(cwd, "commit", "-m", subject);
+  };
+
+  it("lists what merged on the remote since the checkout was last pulled", () => {
+    const dir = mkdtempSync(join(tmpdir(), "draft-changelog-"));
+    try {
+      const origin = join(dir, "origin.git");
+      const author = join(dir, "author");
+      const stale = join(dir, "stale");
+      git(dir, "init", "--bare", "-b", "main", origin);
+      git(dir, "clone", origin, author);
+      land(author, "chore: start");
+      git(author, "tag", "v0.0.1");
+      land(author, "feat: already pulled");
+      git(author, "push", "origin", "main", "--tags");
+      git(dir, "clone", origin, stale);
+      land(author, "fix: merged after the pull");
+      git(author, "push", "origin", "main");
+      cpSync(join(import.meta.dirname, "."), join(stale, "scripts"), { recursive: true });
+      writeFileSync(join(stale, "package.json"), '{"type":"module"}');
+
+      const run = execFileSync(
+        process.execPath,
+        ["--import", import.meta.resolve("tsx"), "scripts/draft-changelog.ts", "0.0.2"],
+        { cwd: stale, encoding: "utf-8", stdio: ["ignore", "pipe", "pipe"] },
+      );
+      assert.match(run, /merged after the pull/i);
+      assert.match(run, /already pulled/i);
+    } finally {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  });
+});

scripts/draft-changelog.ts

@@ -108,8 +108,9 @@ function main() {
 
 function createDraft(options: Options): DraftOutput {
   const versionTag = `v${options.version}`;
-  const to = options.to ?? (tagExists(versionTag) ? versionTag : "HEAD");
+  const to = options.to ?? (tagExists(versionTag) ? versionTag : fetchDraftHead());
   const from = options.from ?? resolvePreviousTag(versionTag, to, options.version);
+  assertHasCommit(from);
   const commits = getCommits(from, to).filter((commit) => !shouldSkipCommit(commit));
   const parsedCommits = commits.map(parseCommit);
 
@@ -204,6 +205,21 @@ function git(args: string[]) {
   }).trim();
 }
 
+/** The remote's main as of now: a stale checkout would otherwise leave out what merged since it was last pulled. */
+function fetchDraftHead() {
+  git(["fetch", "origin", "main", "--tags", "--force"]);
+  console.error(`Drafting from origin/main at ${git(["rev-parse", "--short=9", "origin/main"])}`);
+  return "origin/main";
+}
+
+function assertHasCommit(ref: string) {
+  try {
+    git(["cat-file", "-e", `${ref}^{commit}`]);
+  } catch {
+    fail(`This clone has no objects for ${ref}, so the draft would list the wrong commits.`);
+  }
+}
+
 function tagExists(tag: string) {
   try {
     git(["rev-parse", "--verify", "--quiet", `refs/tags/${tag}`]);