feat: add changesets changelog pull request resolver

packages/changesets-changelog/CHANGELOG.md

@@ -7,4 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add local pull request resolution from Git commit subjects ([#84](https://github.com/MetaMask/release-tools/pull/84))
+
 [Unreleased]: https://github.com/MetaMask/release-tools/

packages/changesets-changelog/package.json

@@ -45,8 +45,13 @@
     "test:verbose": "vitest --reporter=verbose",
     "test:watch": "vitest --watch"
   },
+  "dependencies": {
+    "@changesets/types": "^7.0.0",
+    "execa": "^8.0.1"
+  },
   "devDependencies": {
     "@metamask/auto-changelog": "^6.1.0",
+    "@types/node": "^22.13.14",
     "@typescript/native": "npm:typescript@^7.0.2",
     "@vitest/coverage-istanbul": "^5.0.1",
     "rimraf": "^5.0.5",

packages/changesets-changelog/src/resolve-pull-request.test.ts

@@ -0,0 +1,85 @@
+import type { NewChangesetWithCommit } from '@changesets/types';
+import { execa } from 'execa';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import {
+  extractPullRequestNumber,
+  getPullRequestLink,
+} from './resolve-pull-request.js';
+
+vi.mock('execa', () => ({
+  execa: vi.fn(),
+}));
+
+const mockedExeca = vi.mocked(execa);
+
+const changeset = {
+  id: 'quick-lions-devour',
+  summary: '## Added\n\n- Add a feature',
+  releases: [{ name: 'pkg-a', type: 'minor' }],
+  commit: 'abc1234',
+} as NewChangesetWithCommit;
+
+describe('extractPullRequestNumber', () => {
+  it('extracts a number from a squash-merge subject', () => {
+    expect(extractPullRequestNumber('Add a feature (#1234)')).toBe('1234');
+  });
+
+  it('extracts a number from a merge-commit subject', () => {
+    expect(
+      extractPullRequestNumber('Merge pull request #1234 from owner/feature'),
+    ).toBe('1234');
+  });
+
+  it('throws when a subject has no pull request number', () => {
+    expect(() => extractPullRequestNumber('Add a feature')).toThrow(
+      'does not contain a pull request number',
+    );
+  });
+});
+
+describe('getPullRequestLink', () => {
+  beforeEach(() => {
+    mockedExeca.mockReset();
+  });
+
+  it('reads the commit subject and returns a pull request link', async () => {
+    mockedExeca.mockResolvedValue({ stdout: 'Add a feature (#1234)' } as never);
+
+    expect(await getPullRequestLink(changeset, 'MetaMask/core')).toBe(
+      '[#1234](https://github.com/MetaMask/core/pull/1234)',
+    );
+    expect(mockedExeca).toHaveBeenCalledWith('git', [
+      'show',
+      '-s',
+      '--format=%s',
+      'abc1234',
+    ]);
+  });
+
+  it('throws when the changeset has no commit', async () => {
+    const withoutCommit = { ...changeset };
+    delete withoutCommit.commit;
+    await expect(
+      getPullRequestLink(withoutCommit, 'MetaMask/core'),
+    ).rejects.toThrow('quick-lions-devour has no commit');
+  });
+
+  it('throws when git cannot read the commit', async () => {
+    mockedExeca.mockRejectedValue(new Error('unknown revision'));
+    await expect(
+      getPullRequestLink(changeset, 'MetaMask/core'),
+    ).rejects.toThrow(
+      'Could not read commit abc1234 for changeset quick-lions-devour',
+    );
+  });
+
+  it('throws when git returns an empty subject', async () => {
+    mockedExeca.mockResolvedValue({ stdout: '  ' } as never);
+    await expect(
+      getPullRequestLink(changeset, 'MetaMask/core'),
+    ).rejects.toThrow(
+      'Could not read commit abc1234 for changeset quick-lions-devour',
+    );
+  });
+});

packages/changesets-changelog/src/resolve-pull-request.ts

@@ -0,0 +1,65 @@
+import type { NewChangesetWithCommit } from '@changesets/types';
+import { execa } from 'execa';
+
+const SQUASH_MERGE_PR_PATTERN = /\(#(\d+)\)$/u;
+const MERGE_COMMIT_PR_PATTERN = /Merge pull request #(\d+) from/iu;
+
+/**
+ * Extracts a pull request number from a Git commit subject.
+ *
+ * @param subject - The Git commit subject.
+ * @returns The pull request number.
+ */
+export function extractPullRequestNumber(subject: string): string {
+  const match =
+    subject.match(SQUASH_MERGE_PR_PATTERN) ??
+    subject.match(MERGE_COMMIT_PR_PATTERN);
+
+  if (!match) {
+    throw new Error(
+      `Commit subject does not contain a pull request number: ${subject}`,
+    );
+  }
+
+  return match[1];
+}
+
+/**
+ * Resolves the pull request link for a changeset using its local Git commit.
+ *
+ * @param changeset - The changeset whose commit should be inspected.
+ * @param repo - The GitHub repository in `owner/repo` form.
+ * @returns The Markdown pull request link.
+ */
+export async function getPullRequestLink(
+  changeset: NewChangesetWithCommit,
+  repo: string,
+): Promise<string> {
+  if (!changeset.commit) {
+    throw new Error(`Changeset ${changeset.id} has no commit`);
+  }
+
+  let subject: string;
+  try {
+    ({ stdout: subject } = await execa('git', [
+      'show',
+      '-s',
+      '--format=%s',
+      changeset.commit,
+    ]));
+  } catch (error) {
+    throw new Error(
+      `Could not read commit ${changeset.commit} for changeset ${changeset.id}`,
+      { cause: error },
+    );
+  }
+
+  if (!subject.trim()) {
+    throw new Error(
+      `Could not read commit ${changeset.commit} for changeset ${changeset.id}: empty subject`,
+    );
+  }
+
+  const pullRequestNumber = extractPullRequestNumber(subject.trim());
+  return `[#${pullRequestNumber}](https://github.com/${repo}/pull/${pullRequestNumber})`;
+}

packages/changesets-changelog/tsconfig.build.json

@@ -2,7 +2,8 @@
   "extends": "../../tsconfig.packages.build.json",
   "compilerOptions": {
     "outDir": "./dist",
-    "rootDir": "./src"
+    "rootDir": "./src",
+    "types": ["node"]
   },
   "references": [],
   "include": ["./src"]

packages/changesets-changelog/tsconfig.json

@@ -1,5 +1,8 @@
 {
   "extends": "../../tsconfig.packages.json",
+  "compilerOptions": {
+    "types": ["node"]
+  },
   "references": [],
   "include": ["./src"]
 }

yarn.lock

@@ -1252,9 +1252,12 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@metamask/changesets-changelog@workspace:packages/changesets-changelog"
   dependencies:
+    "@changesets/types": "npm:^7.0.0"
     "@metamask/auto-changelog": "npm:^6.1.0"
+    "@types/node": "npm:^22.13.14"
     "@typescript/native": "npm:typescript@^7.0.2"
     "@vitest/coverage-istanbul": "npm:^5.0.1"
+    execa: "npm:^8.0.1"
     rimraf: "npm:^5.0.5"
     typedoc: "npm:^0.25.13"
     typescript: "npm:@typescript/typescript6@^6.0.2"