chore: Merge remote-tracking branch 'origin/main' into fd-fix-client-components-import

README.md

@@ -1,11 +1,13 @@
 ![Hydrogen logo](/docs/images/HydrogenLogo.png)
 
-📚 [Docs](https://shopify.dev/custom-storefronts/hydrogen)  | 🗣 [Discord](https://discord.gg/Hefq6w5c5d)  |  💬 [Discussions](https://github.com/Shopify/hydrogen/discussions)  |  📝 [Changelog](./packages/hydrogen/CHANGELOG.md)
+📚 [Docs](https://shopify.dev/custom-storefronts/hydrogen) | 🗣 [Discord](https://discord.gg/Hefq6w5c5d) | 💬 [Discussions](https://github.com/Shopify/hydrogen/discussions) | 📝 [Changelog](./packages/hydrogen/CHANGELOG.md)
 
 Hydrogen is a **React-based framework** for building dynamic, **Shopify-powered** custom storefronts.
 
 Spin up a Hydrogen app in your browser with our [playground](https://hydrogen.new/) or set up your local environment with the instructions below ⬇️
 
+**This is a developer preview of Hydrogen**. The documentation will be updated as Shopify [introduces new features and refines existing functionality](https://github.com/Shopify/hydrogen/releases). Production launches of Hydrogen custom storefronts aren't yet supported as Shopify is evolving the Hydrogen framework.
+
 ## Getting Started
 
 **Requirements:**
@@ -63,4 +65,3 @@ Learn more about [getting started with Hydrogen](https://shopify.dev/custom-stor
 - [`@shopify/hydrogen-plugin-sanity`](https://www.npmjs.com/package/@shopify/hydrogen-plugin-sanity)
 - [`create-hydrogen-app`](https://www.npmjs.com/package/create-hydrogen-app)
 - [`eslint-plugin-hydrogen`](https://www.npmjs.com/package/eslint-plugin-hydrogen)
-- [`@shopify/create-hydrogen` (deprecated)](https://www.npmjs.com/package/@shopify/create-hydrogen)

lerna.json

@@ -3,7 +3,7 @@
   "packages": [
     "packages/*"
   ],
-  "version": "0.6.0",
+  "version": "0.6.1",
   "npmClient": "yarn",
   "useWorkspaces": true,
   "command": {}

package.json

@@ -65,7 +65,8 @@
     "ts-node": "^10.2.1",
     "typescript": "^4.2.3",
     "vite": "^2.6.0",
-    "yorkie": "^2.0.0"
+    "yorkie": "^2.0.0",
+    "glob": "^7.2.0"
   },
   "gitHooks": {
     "pre-commit": "lint-staged",

packages/cli/CHANGELOG.md

@@ -5,7 +5,9 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-<!-- ## Unreleased -->
+## Unreleased
+
+- Add ability to explicitly set the root for the running command using the `--root` flag
 
 ## 0.6.0 - 2021-11-05
 

packages/cli/src/commands/init/init.ts

@@ -13,7 +13,7 @@ export enum Template {
  * Create a new `@shopify/hydrogen` app.
  */
 export async function init(env: Env) {
-  const {ui, fs, workspace} = env;
+  const {ui, fs, workspace, ...passThroughEnv} = env;
 
   const name = await ui.ask('What do you want to name this app?', {
     validate: validateProjectName,
@@ -43,8 +43,8 @@ export async function init(env: Env) {
   );
 
   if (template === Template.None) {
-    const context = {name};
-    await app({ui, fs, workspace, context});
+    const context = {name, ...passThroughEnv.context};
+    await app({...passThroughEnv, ui, fs, workspace, context});
   }
 
   if (template === Template.Default) {

packages/cli/src/index.ts

@@ -4,9 +4,14 @@ import {Cli} from './ui';
 import {Workspace} from './workspace';
 import {Fs} from './fs';
 import {loadConfig} from './config';
+import {Env} from './types';
 
 const logger = debug('hydrogen');
 
+interface ModuleType {
+  default: (env: Env) => Promise<void>;
+}
+
 (async () => {
   const rawInputs = process.argv.slice(2);
   const {command, root} = parseCliArguments(rawInputs);
@@ -22,10 +27,23 @@ const logger = debug('hydrogen');
     throw new InputError();
   }
 
+  async function runModule(module: ModuleType) {
+    logger('Run start');
+
+    await module.default({
+      ui,
+      fs,
+      workspace,
+      logger: debug(`hydrogen/${command}`),
+    });
+
+    logger('Run end');
+  }
+
   try {
     const module = await import(`./commands/${command}`);
 
-    await module.default({ui, fs, workspace});
+    await runModule(module);
   } catch (error) {
     logger(error);
 
@@ -36,7 +54,9 @@ const logger = debug('hydrogen');
     ui.printFile(file);
   }
 
-  await workspace.commit();
+  if (command === 'init') {
+    await workspace.commit();
+  }
 })().catch((error) => {
   logger(error);
   process.exitCode = 1;

packages/cli/src/types.ts

@@ -1,3 +1,4 @@
+import debug from 'debug';
 import {Workspace} from './workspace';
 import {Ui} from './ui';
 import {Fs} from './fs';
@@ -9,6 +10,7 @@ export interface Env<Context = {}> {
   workspace: Workspace;
   fs: Fs;
   context?: Context;
+  logger: debug.Debugger;
 }
 
 export enum ComponentType {

packages/cli/src/utilities/index.ts

@@ -1,4 +1,4 @@
-import {join, resolve} from 'path';
+import {resolve} from 'path';
 
 import minimist from 'minimist';
 
@@ -15,10 +15,8 @@ const DEFAULT_SUBCOMMANDS = {
 export function parseCliArguments(rawInputs?: string[]) {
   const inputs = minimist(rawInputs || []);
   const command = inputs._[0];
-  const root =
-    command === 'create' && inputs._[2]
-      ? join(process.cwd(), inputs._[2])
-      : process.cwd();
+
+  const root = inputs.root || process.cwd();
   const subcommand =
     inputs._[1] || DEFAULT_SUBCOMMANDS[command as 'create' | 'version'];
   const {debug} = inputs;

packages/create-hydrogen-app/CHANGELOG.md

@@ -7,6 +7,11 @@ and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 <!-- ## Unreleased -->
 
+## 0.6.1 - 2021-11-08
+
+- Wrap LocalizationProvider in a proper Suspense boundary
+- Optimize `@headlessui/react` to prevent dev server slowness while we investigate a long term solution
+
 ## 0.6.0 - 2021-11-05
 
 - No updates. Transitive dependency bump.

packages/create-hydrogen-app/package.json

@@ -4,7 +4,7 @@
     "access": "public",
     "@shopify:registry": "https://registry.npmjs.org"
   },
-  "version": "0.6.0",
+  "version": "0.6.1",
   "main": "index.js",
   "license": "MIT",
   "bin": {

packages/dev/package.json

@@ -1,7 +1,7 @@
 {
   "name": "dev",
   "description": "This is a dev environment for Hydrogen",
-  "version": "0.6.0",
+  "version": "0.6.1",
   "license": "MIT",
   "private": true,
   "scripts": {
@@ -32,7 +32,7 @@
   },
   "dependencies": {
     "@headlessui/react": "^1.4.1",
-    "@shopify/hydrogen": "^0.6.0",
+    "@shopify/hydrogen": "^0.6.1",
     "compression": "^1.7.4",
     "express": "^4.17.1",
     "graphql-tag": "^2.12.4",

packages/dev/src/App.server.jsx

@@ -17,10 +17,10 @@ export default function App({...serverState}) {
   const pages = import.meta.globEager('./pages/**/*.server.[jt]sx');
 
   return (
-    <ShopifyServerProvider shopifyConfig={shopifyConfig} {...serverState}>
-      <LocalizationProvider>
-        <CartProvider>
-          <Suspense fallback={<LoadingFallback />}>
+    <Suspense fallback={<LoadingFallback />}>
+      <ShopifyServerProvider shopifyConfig={shopifyConfig} {...serverState}>
+        <LocalizationProvider>
+          <CartProvider>
             <DefaultSeo />
             <Switch>
               <DefaultRoutes
@@ -29,9 +29,9 @@ export default function App({...serverState}) {
                 fallback={<NotFound />}
               />
             </Switch>
-          </Suspense>
-        </CartProvider>
-      </LocalizationProvider>
-    </ShopifyServerProvider>
+          </CartProvider>
+        </LocalizationProvider>
+      </ShopifyServerProvider>
+    </Suspense>
   );
 }

packages/eslint-plugin/CHANGELOG.md

@@ -5,7 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-<!-- ## Unreleased -->
+## Unreleased
+
+- Added new `hydrogen/typescript` config
+- Added `env#node: true` and `parserOptions#sourceType: 'module'` to core config
+- Fixed issue requiring typescript to be install on non-typescript projects
 
 ## 0.6.0 - 2021-11-05
 

packages/eslint-plugin/package.json

@@ -42,7 +42,6 @@
     "ts-jest": "^26.5.4"
   },
   "peerDependencies": {
-    "@typescript-eslint/eslint-plugin": ">= 4",
     "eslint": ">=5"
   }
 }

packages/eslint-plugin/src/config/recommended-typescript.ts

@@ -1,12 +0,0 @@
-import rules from './rules';
-
-export default {
-  plugins: ['hydrogen'],
-  extends: [
-    'plugin:@shopify/typescript',
-    'plugin:@shopify/react',
-    'plugin:@shopify/node',
-    'plugin:@shopify/prettier',
-  ],
-  rules,
-};

packages/eslint-plugin/src/config/recommended.ts

@@ -1,12 +0,0 @@
-import rules from './rules';
-
-export default {
-  plugins: ['hydrogen'],
-  extends: [
-    'plugin:@shopify/esnext',
-    'plugin:@shopify/react',
-    'plugin:@shopify/node',
-    'plugin:@shopify/prettier',
-  ],
-  rules,
-};

packages/eslint-plugin/src/config/rules/hydrogen.ts

@@ -1,4 +0,0 @@
-export default {
-  'hydrogen/no-state-in-server-components': 'error',
-  'hydrogen/prefer-image-component': 'error',
-};

packages/eslint-plugin/src/config/rules/index.ts

@@ -1,5 +0,0 @@
-import {deepMerge} from '@typescript-eslint/experimental-utils/dist/eslint-utils';
-import overrides from './overrides';
-import hydrogen from './hydrogen';
-
-export default deepMerge(hydrogen, overrides);

packages/eslint-plugin/src/config/rules/overrides.ts

@@ -1,45 +0,0 @@
-export default {
-  // TODO: We may want to change the configuration for the following 3 rules
-  'jsx-a11y/click-events-have-key-events': 'off',
-  'jsx-a11y/no-noninteractive-element-interactions': 'off',
-  'react/jsx-filename-extension': ['error', {extensions: ['.tsx', '.jsx']}],
-
-  /**
-   * Rules below this line are intentionally disabled for different reasons
-   */
-
-  // The following 2 rules are very strict and disabled here to lessen developer frustration
-  '@shopify/jsx-no-hardcoded-content': 'off',
-  '@shopify/jsx-no-complex-expressions': 'off',
-
-  /**
-   * eslint overrides
-   */
-
-  // We often define GraphQL queries at the bottom of the file which would be a violation for this rule
-  'no-use-before-define': 'off',
-  // We agree that warning comments acceptable
-  'no-warning-comments': 'off',
-
-  /**
-   * react overrides
-   */
-
-  // Following Next.js and likely this will be the default in most frameworks
-  'react/react-in-jsx-scope': 'off',
-  // We default to typescript for typing, non typescript projects can override this rule if they want
-  'react/prop-types': 'off',
-
-  /**
-   * import overrides
-   */
-
-  // TODO: We should turn these on, at least partially
-  // 'import/no-unresolved': ['off'],
-  // 'import/extensions': ['off'],
-
-  // These two rules result in a significant number of false positives so we
-  // need to keep them disabled.
-  'jsx-a11y/label-has-for': 'off',
-  'jsx-a11y/control-has-associated-label': 'off',
-};

packages/eslint-plugin/src/configs/core.ts

@@ -11,6 +11,7 @@ export default {
   env: {
     es2021: true,
     browser: true,
+    node: true,
   },
   settings: {
     react: {
@@ -21,6 +22,7 @@ export default {
     ecmaFeatures: {
       jsx: true,
     },
+    sourceType: 'module',
   },
   rules: {
     'no-console': 'warn',
@@ -39,54 +41,6 @@ export default {
   },
   ignorePatterns: ['node_modules/', 'build/', '*.graphql.d.ts', '*.graphql.ts'],
   overrides: [
-    {
-      files: ['*.ts', '*.tsx'],
-      parser: '@typescript-eslint/parser',
-      extends: ['plugin:@typescript-eslint/recommended'],
-      rules: {
-        'react/prop-types': 'off',
-        '@typescript-eslint/no-explicit-any': 'off',
-        '@typescript-eslint/no-non-null-assertion': 'off',
-        '@typescript-eslint/explicit-module-boundary-types': 'off',
-        '@typescript-eslint/no-unused-vars': 'off',
-        '@typescript-eslint/no-empty-interface': 'off',
-        '@typescript-eslint/ban-types': [
-          'error',
-          {
-            types: {
-              String: {message: 'Use string instead', fixWith: 'string'},
-              Boolean: {message: 'Use boolean instead', fixWith: 'boolean'},
-              Number: {message: 'Use number instead', fixWith: 'number'},
-              Object: {message: 'Use object instead', fixWith: 'object'},
-              Array: {message: 'Provide a more specific type'},
-              ReadonlyArray: {message: 'Provide a more specific type'},
-            },
-          },
-        ],
-        '@typescript-eslint/naming-convention': [
-          'error',
-          {
-            selector: 'default',
-            format: ['camelCase', 'PascalCase', 'UPPER_CASE'],
-            leadingUnderscore: 'allowSingleOrDouble',
-            trailingUnderscore: 'allowSingleOrDouble',
-          },
-          {
-            selector: 'typeLike',
-            format: ['PascalCase'],
-          },
-          {
-            selector: 'typeParameter',
-            format: ['PascalCase'],
-            leadingUnderscore: 'allow',
-          },
-          {
-            selector: 'interface',
-            format: ['PascalCase'],
-          },
-        ],
-      },
-    },
     {
       files: ['*.test.*'],
       plugins: ['jest'],

packages/eslint-plugin/src/configs/typescript.ts

@@ -0,0 +1,52 @@
+export default {
+  overrides: [
+    {
+      files: ['*.ts', '*.tsx'],
+      parser: '@typescript-eslint/parser',
+      extends: ['plugin:@typescript-eslint/recommended'],
+      rules: {
+        'react/prop-types': 'off',
+        '@typescript-eslint/no-explicit-any': 'off',
+        '@typescript-eslint/no-non-null-assertion': 'off',
+        '@typescript-eslint/explicit-module-boundary-types': 'off',
+        '@typescript-eslint/no-unused-vars': 'off',
+        '@typescript-eslint/no-empty-interface': 'off',
+        '@typescript-eslint/ban-types': [
+          'error',
+          {
+            types: {
+              String: {message: 'Use string instead', fixWith: 'string'},
+              Boolean: {message: 'Use boolean instead', fixWith: 'boolean'},
+              Number: {message: 'Use number instead', fixWith: 'number'},
+              Object: {message: 'Use object instead', fixWith: 'object'},
+              Array: {message: 'Provide a more specific type'},
+              ReadonlyArray: {message: 'Provide a more specific type'},
+            },
+          },
+        ],
+        '@typescript-eslint/naming-convention': [
+          'error',
+          {
+            selector: 'default',
+            format: ['camelCase', 'PascalCase', 'UPPER_CASE'],
+            leadingUnderscore: 'allowSingleOrDouble',
+            trailingUnderscore: 'allowSingleOrDouble',
+          },
+          {
+            selector: 'typeLike',
+            format: ['PascalCase'],
+          },
+          {
+            selector: 'typeParameter',
+            format: ['PascalCase'],
+            leadingUnderscore: 'allow',
+          },
+          {
+            selector: 'interface',
+            format: ['PascalCase'],
+          },
+        ],
+      },
+    },
+  ],
+};

packages/eslint-plugin/src/index.ts

@@ -1,9 +1,11 @@
 import recommended from './configs/recommended';
 import hydrogen from './configs/hydrogen';
+import typescript from './configs/typescript';
 
 export {rules} from './rules';
 
 export const configs = {
   recommended,
   hydrogen,
+  typescript,
 };

packages/generate-docs/src/DocsGen.ts

@@ -142,10 +142,11 @@ export class DocsGen {
 
         await componentResult.docs(componentEntryBase);
 
-        await Promise.all([
-          componentResult.writeReadme(componentEntryBase),
-          componentResult.writeDevDoc(componentPaths.output),
-        ]);
+        await componentResult.writeReadme(componentEntryBase);
+
+        if (this.writeDocs) {
+          componentResult.writeDevDoc(componentPaths.output);
+        }
 
         listItems.push({
           name: `<a href="${componentUrl}">${name}</a>`,

packages/generate-docs/src/FileResult.ts

@@ -25,7 +25,7 @@ export class FileResult {
   public async writeDevDoc(path: string) {
     const result = inPageAnchors(this.staged.join(''));
 
-    const comment = `<!-- This file is generated from the source code and any changes you make here will be overwritten. -->`;
+    const comment = `<!-- This file is generated from source code in the Shopify/hydrogen repo. Any changes you make here will be overwritten. -->`;
 
     await this.write(path, [this.frontMatter, comment, result].join('\n\n'));
   }
@@ -38,7 +38,7 @@ export class FileResult {
 
       const localPath = path.replace(resolve('.'), '');
       const finalPath = resolve(path, 'README.md');
-      const comment = `<!-- This file is generated from the source code. Edit the files in ${localPath} and run 'yarn generate-docs' at the root of this repo. -->`;
+      const comment = `<!-- This file is generated from source code in the Shopify/hydrogen repo. Edit the files in ${localPath} and run 'yarn generate-docs' at the root of this repo. -->`;
       await this.write(
         finalPath,
         [comment, ...this.staged].join('\n\n').trim()

packages/hydrogen-plugin-sanity/CHANGELOG.md

@@ -7,6 +7,10 @@ and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 <!-- ## Unreleased -->
 
+## 0.6.1 - 2021-11-08
+
+- No updates. Transitive dependency bump.
+
 ## 0.6.0 - 2021-11-05
 
 - No updates. Transitive dependency bump.

packages/hydrogen-plugin-sanity/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@shopify/hydrogen-plugin-sanity",
-  "version": "0.6.0",
+  "version": "0.6.1",
   "description": "Hydrogen plugins for integrating with Sanity",
   "main": "dist/esnext/index.js",
   "publishConfig": {
@@ -17,7 +17,7 @@
     "prepack": "yarn build"
   },
   "devDependencies": {
-    "@shopify/hydrogen": "^0.6.0"
+    "@shopify/hydrogen": "^0.6.1"
   },
   "peerDependencies": {
     "@shopify/hydrogen": "^0.4.0"

packages/hydrogen/CHANGELOG.md

@@ -5,7 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-<!-- ## Unreleased -->
+## Unreleased
+
+- fix: reading property of null for component props
+
+## 0.6.1 - 2021-11-08
+
+- No updates. Transitive dependency bump.
 
 ## 0.6.0 - 2021-11-05
 

packages/hydrogen/package.json

@@ -4,7 +4,7 @@
     "access": "public",
     "@shopify:registry": "https://registry.npmjs.org"
   },
-  "version": "0.6.0",
+  "version": "0.6.1",
   "description": "Modern custom Shopify storefronts",
   "license": "MIT",
   "main": "dist/esnext/index.js",

packages/hydrogen/src/framework/Hydration/react-utils.ts

@@ -30,6 +30,7 @@ export function renderReactProps(props: any) {
 function renderReactProp(prop: any): any {
   if (
     typeof prop === 'object' &&
+    prop !== null &&
     prop['$$typeof'] === Symbol.for('react.element')
   ) {
     if (prop.type instanceof Function) {

packages/hydrogen/src/version.ts

@@ -1 +1 @@
-export const LIB_VERSION = '0.6.0';
+export const LIB_VERSION = '0.6.1';

packages/playground/server-components-worker/package.json

@@ -1,7 +1,7 @@
 {
   "name": "server-components-worker",
   "private": true,
-  "version": "0.6.0",
+  "version": "0.6.1",
   "scripts": {
     "dev": "DEV=true node start-worker",
     "build": "yarn build:client && yarn build:worker",
@@ -13,7 +13,7 @@
   },
   "dependencies": {
     "@cloudflare/kv-asset-handler": "*",
-    "@shopify/hydrogen": "^0.6.0",
+    "@shopify/hydrogen": "^0.6.1",
     "miniflare": "^1.3.3",
     "react": "18.0.0-alpha-e6be2d531",
     "react-dom": "18.0.0-alpha-e6be2d531",

packages/playground/server-components/package.json

@@ -1,7 +1,7 @@
 {
   "name": "test-server-components",
   "private": true,
-  "version": "0.6.0",
+  "version": "0.6.1",
   "scripts": {
     "dev": "vite",
     "build": "yarn build:client && yarn build:server",
@@ -12,7 +12,7 @@
     "vite": "^2.6.0"
   },
   "dependencies": {
-    "@shopify/hydrogen": "^0.6.0",
+    "@shopify/hydrogen": "^0.6.1",
     "react": "18.0.0-alpha-e6be2d531",
     "react-dom": "18.0.0-alpha-e6be2d531",
     "react-router-dom": "^5.2.0"

tests/changelogs.test.ts

@@ -0,0 +1,154 @@
+import {join, resolve} from 'path';
+
+import {readFileSync} from 'fs-extra';
+import glob from 'glob';
+
+const ROOT_PATH = resolve(__dirname, '..');
+
+const HEADER_START_REGEX = /^## /;
+const CHANGELOG_INTRO = `# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).`;
+
+readChangelogs().forEach(({packageChangelogPath, packageChangelog}) => {
+  describe(`changelog consistency for ${packageChangelogPath}`, () => {
+    it('begins with the "Keep a Changelog" intro section', () => {
+      const actualIntro = packageChangelog.substring(0, CHANGELOG_INTRO.length);
+
+      expect(actualIntro).toBe(CHANGELOG_INTRO);
+    });
+
+    it('contains only known headers', () => {
+      const headerLines = packageChangelog
+        .split('\n')
+        .filter((line) => /^\s*#/.exec(line));
+      const offendingHeaders = headerLines.filter(
+        (headerLine) => !headerIsAllowed(headerLine)
+      );
+
+      expect(offendingHeaders).toStrictEqual([]);
+    });
+
+    it('has exactly 1 empty line before headings', () => {
+      const notEnoughSpacingBeforeHeadings = /[^\n]+\n^#.*$/gm;
+
+      expect(packageChangelog).not.toStrictEqual(
+        expect.stringMatching(notEnoughSpacingBeforeHeadings)
+      );
+    });
+
+    it('has exactly 1 empty line after headings', () => {
+      const notEnoughSpacingAfterHeadings = /^#.*$\n[^\n]+/gm;
+
+      expect(packageChangelog).not.toStrictEqual(
+        expect.stringMatching(notEnoughSpacingAfterHeadings)
+      );
+    });
+
+    it('contains an Unreleased header with content, or a commented out Unreleased header with no content', () => {
+      // One of the following must be present
+      // - An Unreleased header, that is immediatly preceded by a level 3 heading ("Changed" etc)
+      // - An Unreleased header, that is immediatly preceded by a bullet ("- ...")
+      // - A commented out Unreleased header, that is immediatly preceded by a level 2 heading (Version info)
+
+      const unreleasedHeaderWithContent = /^## Unreleased\n\n- /gm;
+      const unreleasedHeaderWithSubHeader = /^## Unreleased\n\n### /gm;
+      const commentedUnreleasedHeaderWithNoContent =
+        /^<!-- ## Unreleased -->\n\n## /gm;
+
+      expect([
+        unreleasedHeaderWithContent.test(packageChangelog) ||
+          unreleasedHeaderWithSubHeader.test(packageChangelog),
+        commentedUnreleasedHeaderWithNoContent.test(packageChangelog),
+      ]).toContain(true);
+    });
+
+    it('does not contain duplicate headers', () => {
+      const headerLines = packageChangelog
+        .split('\n')
+        .filter(
+          (line) => HEADER_START_REGEX.exec(line) || /## Unreleased/.exec(line)
+        )
+        .sort();
+      const uniqueHeaderLines = headerLines.filter(
+        (element, index, array) => array.indexOf(element) === index
+      );
+
+      expect(headerLines).toStrictEqual(uniqueHeaderLines);
+    });
+  });
+});
+
+const allowedHeaders = [
+  '# Changelog',
+  '## Unreleased',
+  /^## \d+\.\d+\.\d-\w+\.\d+ - \d\d\d\d-\d\d-\d\d$/, // -alpha.x releases
+  /^## \d+\.\d+\.\d+ - \d\d\d\d-\d\d-\d\d$/,
+  '### Fixed',
+  '### Added',
+  '### Changed',
+  '### Deprecated',
+  '### Removed',
+  '### Security',
+  /^####/,
+];
+
+function headerIsAllowed(headerLine) {
+  return allowedHeaders.some((allowedHeader) => {
+    if (allowedHeader instanceof RegExp) {
+      return allowedHeader.test(headerLine);
+    } else {
+      return allowedHeader === headerLine;
+    }
+  });
+}
+
+function readChangelogs() {
+  const packagesPath = join(ROOT_PATH, 'packages');
+
+  return glob
+    .sync(join(packagesPath, '*/'))
+    .filter(hasPackageJSON)
+    .filter(hasChangelog)
+    .map((packageDir) => {
+      const packageChangelogPath = join(packageDir, 'CHANGELOG.md');
+      const packageChangelog = safeReadSync(packageChangelogPath, {
+        encoding: 'utf8',
+      }).toString('utf-8');
+
+      return {
+        packageDir,
+        packageChangelogPath,
+        packageChangelog,
+      };
+    });
+}
+
+function safeReadSync(path, options) {
+  try {
+    return readFileSync(path, options);
+  } catch {
+    return '';
+  }
+}
+
+function hasChangelog(packageDir) {
+  const changelogJSONPath = join(packageDir, 'CHANGELOG.md');
+  const changelog = safeReadSync(changelogJSONPath, {
+    encoding: 'utf8',
+  });
+
+  return changelog.length > 0;
+}
+
+function hasPackageJSON(packageDir) {
+  const packageJSONPath = join(packageDir, 'package.json');
+  const packageJSON = safeReadSync(packageJSONPath, {
+    encoding: 'utf8',
+  });
+
+  return packageJSON.length > 0;
+}