Generate the changelog automatically (#50323)

Summary:
This change implements the automatic generation of the Changelog in CI while doing a release.
The output is a PR opened by the react-native-bot that can be manipulated and imported by Meta engineers

## Changelog:
[Internal] - Generate the changelog automatically

Pull Request resolved: #50323

Test Plan:
Tested as a separated workflow first:
<img width="1624" alt="Screenshot 2025-03-27 at 17 44 47" src="https://github.com/user-attachments/assets/b8877cdb-f63b-4d82-b340-54f612ac0cd4" />
this generated the PR:
#50328

I also added jest tests:
<img width="516" alt="Screenshot 2025-03-27 at 17 45 39" src="https://github.com/user-attachments/assets/7ebbc310-e41e-48fc-997e-21366c7306cf" />

Reviewed By: cortinico

Differential Revision: D71986909

Pulled By: cipolleschi

fbshipit-source-id: 10ffaf342bb0642a6992a107185b6704815b16e3

Author: cipolleschi

.github/workflow-scripts/__tests__/generateChangelog-test.js

@@ -0,0 +1,251 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+const {
+  generateChangelog,
+  _computePreviousVersionFrom,
+  _generateChangelog,
+  _pushCommit,
+  _createPR,
+} = require('../generateChangelog');
+
+const silence = () => {};
+const mockGetNpmPackageInfo = jest.fn();
+const mockExecSync = jest.fn();
+const mockRun = jest.fn();
+const mockFetch = jest.fn();
+const mockExit = jest.fn();
+
+jest.mock('../utils.js', () => ({
+  log: silence,
+  run: mockRun,
+  getNpmPackageInfo: mockGetNpmPackageInfo,
+}));
+
+process.exit = mockExit;
+global.fetch = mockFetch;
+
+describe('Generate Changelog', () => {
+  beforeEach(jest.clearAllMocks);
+
+  describe('_computePreviousVersionFrom', () => {
+    it('returns rc.0 when rc is 1', async () => {
+      const currentVersion = '0.78.0-rc.1';
+      const expectedVersion = '0.78.0-rc.0';
+
+      const receivedVersion = await _computePreviousVersionFrom(currentVersion);
+
+      expect(receivedVersion).toEqual(expectedVersion);
+    });
+
+    it('returns previous rc version when rc is > 1', async () => {
+      const currentVersion = '0.78.0-rc.5';
+      const expectedVersion = '0.78.0-rc.4';
+
+      const receivedVersion = await _computePreviousVersionFrom(currentVersion);
+
+      expect(receivedVersion).toEqual(expectedVersion);
+    });
+
+    it('returns previous patch version when rc is 0', async () => {
+      const currentVersion = '0.78.0-rc.0';
+      const expectedVersion = '0.77.1';
+
+      mockGetNpmPackageInfo.mockReturnValueOnce(
+        Promise.resolve({version: '0.77.1'}),
+      );
+
+      const receivedVersion = await _computePreviousVersionFrom(currentVersion);
+
+      expect(receivedVersion).toEqual(expectedVersion);
+    });
+
+    it('returns patch 0 when patch is 1', async () => {
+      const currentVersion = '0.78.1';
+      const expectedVersion = '0.78.0';
+
+      const receivedVersion = await _computePreviousVersionFrom(currentVersion);
+
+      expect(receivedVersion).toEqual(expectedVersion);
+    });
+
+    it('returns previous patch when patch is > 1', async () => {
+      const currentVersion = '0.78.5';
+      const expectedVersion = '0.78.4';
+
+      const receivedVersion = await _computePreviousVersionFrom(currentVersion);
+
+      expect(receivedVersion).toEqual(expectedVersion);
+    });
+
+    it('returns null when patch is 0', async () => {
+      const currentVersion = '0.78.0';
+
+      const receivedVersion = await _computePreviousVersionFrom(currentVersion);
+
+      expect(receivedVersion).toBeNull();
+    });
+
+    it("throws an error when the version can't be parsed", async () => {
+      const currentVersion = '0.78.0-rc0';
+
+      await expect(
+        _computePreviousVersionFrom(currentVersion),
+      ).rejects.toThrow();
+    });
+  });
+
+  describe('_generateChangelog', () => {
+    it('calls git in the right order', async () => {
+      const currentVersion = '0.79.0-rc5';
+      const previousVersion = '0.79.0-rc4';
+      const token = 'token';
+
+      expectedCommandArgs = [
+        '@rnx-kit/rn-changelog-generator',
+        '--base',
+        `v${previousVersion}`,
+        '--compare',
+        `v${currentVersion}`,
+        '--repo',
+        '.',
+        '--changelog',
+        './CHANGELOG.md',
+        '--token',
+        `${token}`,
+      ];
+
+      _generateChangelog(previousVersion, currentVersion, token);
+
+      expect(mockRun).toHaveBeenCalledTimes(4);
+      expect(mockRun).toHaveBeenNthCalledWith(1, 'git checkout main');
+      expect(mockRun).toHaveBeenNthCalledWith(2, 'git fetch');
+      expect(mockRun).toHaveBeenNthCalledWith(3, 'git pull origin main');
+      expect(mockRun).toHaveBeenNthCalledWith(
+        4,
+        `npx ${expectedCommandArgs.join(' ')}`,
+      );
+    });
+  });
+
+  describe('_pushCommit', () => {
+    it('calls git in the right order', async () => {
+      const currentVersion = '0.79.0-rc5';
+
+      _pushCommit(currentVersion);
+
+      expect(mockRun).toHaveBeenCalledTimes(4);
+      expect(mockRun).toHaveBeenNthCalledWith(
+        1,
+        `git checkout -b changelog/v${currentVersion}`,
+      );
+      expect(mockRun).toHaveBeenNthCalledWith(2, 'git add CHANGELOG.md');
+      expect(mockRun).toHaveBeenNthCalledWith(
+        3,
+        `git commit -m "[RN][Changelog] Add changelog for v${currentVersion}"`,
+      );
+      expect(mockRun).toHaveBeenNthCalledWith(
+        4,
+        `git push origin changelog/v${currentVersion}`,
+      );
+    });
+  });
+
+  describe('_createPR', () => {
+    it('throws error when status is not 201', async () => {
+      const currentVersion = '0.79.0-rc5';
+      const token = 'token';
+
+      mockFetch.mockReturnValueOnce(Promise.resolve({status: 401}));
+
+      const headers = {
+        Accept: 'Accept: application/vnd.github+json',
+        'X-GitHub-Api-Version': '2022-11-28',
+        Authorization: `Bearer ${token}`,
+      };
+
+      const content = `
+## Summary
+Add Changelog for ${currentVersion}
+
+## Changelog:
+[Internal] - Add Changelog for ${currentVersion}
+
+## Test Plan:
+N/A`;
+
+      const body = {
+        title: `[RN][Changelog] Add changelog for v${currentVersion}`,
+        head: `changelog/v${currentVersion}`,
+        base: 'main',
+        body: content,
+      };
+
+      await expect(_createPR(currentVersion, token)).rejects.toThrow();
+
+      expect(mockFetch).toHaveBeenCalledTimes(1);
+      expect(mockFetch).toHaveBeenCalledWith(
+        'https://api.github.com/repos/facebook/react-native/pulls',
+        {
+          method: 'POST',
+          headers: headers,
+          body: JSON.stringify(body),
+        },
+      );
+    });
+    it('Returns the pr url', async () => {
+      const currentVersion = '0.79.0-rc5';
+      const token = 'token';
+      const expectedPrURL =
+        'https://github.com/facebook/react-native/pulls/1234';
+
+      const returnedObject = {
+        status: 201,
+        json: () => Promise.resolve({html_url: expectedPrURL}),
+      };
+      mockFetch.mockReturnValueOnce(Promise.resolve(returnedObject));
+
+      const headers = {
+        Accept: 'Accept: application/vnd.github+json',
+        'X-GitHub-Api-Version': '2022-11-28',
+        Authorization: `Bearer ${token}`,
+      };
+
+      const content = `
+## Summary
+Add Changelog for ${currentVersion}
+
+## Changelog:
+[Internal] - Add Changelog for ${currentVersion}
+
+## Test Plan:
+N/A`;
+
+      const body = {
+        title: `[RN][Changelog] Add changelog for v${currentVersion}`,
+        head: `changelog/v${currentVersion}`,
+        base: 'main',
+        body: content,
+      };
+
+      const receivedPrURL = await _createPR(currentVersion, token);
+
+      expect(mockFetch).toHaveBeenCalledTimes(1);
+      expect(mockFetch).toHaveBeenCalledWith(
+        'https://api.github.com/repos/facebook/react-native/pulls',
+        {
+          method: 'POST',
+          headers: headers,
+          body: JSON.stringify(body),
+        },
+      );
+      expect(receivedPrURL).toEqual(expectedPrURL);
+    });
+  });
+});

.github/workflow-scripts/generateChangelog.js

@@ -0,0 +1,120 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+const {log, getNpmPackageInfo, run} = require('./utils');
+
+async function _computePreviousVersionFrom(version) {
+  log(`Computing previous version from: ${version}`);
+  const regex = /^0\.(\d+)\.(\d+)(-rc\.(\d+))?$/;
+  const match = version.match(regex);
+  if (!match) {
+    throw new Error(`Invalid version format: ${version}`);
+  }
+
+  const minor = match[1];
+  const patch = match[2];
+  const rc = match[4];
+
+  if (rc) {
+    if (Number(rc) > 0) {
+      return `0.${minor}.${patch}-rc.${Number(rc) - 1}`;
+    }
+    //fetch latest version on NPM
+    const latestPkg = await getNpmPackageInfo('react-native', 'latest');
+    return latestPkg.version;
+  } else {
+    if (Number(patch) === 0) {
+      // No need to generate the changelog for 0.X.0 as we already generated it from RCs
+      log(
+        `Skipping changelog generation for ${version} as we already have it from the RCs`,
+      );
+      return null;
+    }
+    return `0.${minor}.${Number(patch) - 1}`;
+  }
+}
+
+function _generateChangelog(previousVersion, version, token) {
+  log(`Generating changelog for ${version} from ${previousVersion}`);
+  run('git checkout main');
+  run('git fetch');
+  run('git pull origin main');
+  const generateChangelogComand = `npx @rnx-kit/rn-changelog-generator --base v${previousVersion} --compare v${version} --repo . --changelog ./CHANGELOG.md --token ${token}`;
+  run(generateChangelogComand);
+}
+
+function _pushCommit(version) {
+  log(`Pushing commit to changelog/v${version}`);
+  run(`git checkout -b changelog/v${version}`);
+  run('git add CHANGELOG.md');
+  run(`git commit -m "[RN][Changelog] Add changelog for v${version}"`);
+  run(`git push origin changelog/v${version}`);
+}
+
+async function _createPR(version, token) {
+  log('Creating changelog pr');
+  const url = 'https://api.github.com/repos/facebook/react-native/pulls';
+  const body = `
+## Summary
+Add Changelog for ${version}
+
+## Changelog:
+[Internal] - Add Changelog for ${version}
+
+## Test Plan:
+N/A`;
+
+  const response = await fetch(url, {
+    method: 'POST',
+    headers: {
+      Accept: 'Accept: application/vnd.github+json',
+      'X-GitHub-Api-Version': '2022-11-28',
+      Authorization: `Bearer ${token}`,
+    },
+    body: JSON.stringify({
+      title: `[RN][Changelog] Add changelog for v${version}`,
+      head: `changelog/v${version}`,
+      base: 'main',
+      body: body,
+    }),
+  });
+
+  if (response.status !== 201) {
+    throw new Error(
+      `Failed to create PR: ${response.status} ${response.statusText}`,
+    );
+  }
+
+  const data = await response.json();
+  return data.html_url;
+}
+
+async function generateChangelog(version, token) {
+  if (version.startsWith('v')) {
+    version = version.substring(1);
+  }
+
+  const previousVersion = await _computePreviousVersionFrom(version);
+  if (previousVersion) {
+    log(`Previous version is ${previousVersion}`);
+    _generateChangelog(previousVersion, version, token);
+    _pushCommit(version);
+    const prURL = await _createPR(version, token);
+    log(`Created PR: ${prURL}`);
+  }
+}
+
+module.exports = {
+  generateChangelog,
+  // Exported only for testing purposes:
+  _computePreviousVersionFrom,
+  _generateChangelog,
+  _pushCommit,
+  _createPR,
+};