Convert codebase to ESM

__tests__/comment-renderer.test.ts

@@ -1,13 +1,14 @@
-import * as core from '@actions/core'
 import {beforeEach, describe, expect, it, jest} from '@jest/globals'
 import dedent from 'dedent'
 
-import {CommentRendererImpl} from '../src/comment-renderer'
+import * as core from './moduleMocks/core'
+jest.unstable_mockModule('@actions/core', () => core)
 
-jest.mock('@actions/core')
+import {CommentRenderer} from '../src/comment-renderer'
+const {CommentRendererImpl} = await import('../src/comment-renderer')
 
 describe('CommentRendererImpl', () => {
-  let renderer: CommentRendererImpl
+  let renderer: CommentRenderer
 
   beforeEach(() => {
     renderer = new CommentRendererImpl()

__tests__/configuration-reader.test.ts

@@ -40,7 +40,7 @@ describe('ConfigurationReaderImpl', () => {
 
     it('returns configuration from .github/codemention.yml', async () => {
       const fileContents = fs.readFileSync(
-        path.join(__dirname, 'fixtures', 'codemention.yml'),
+        path.join(import.meta.dirname, 'fixtures', 'codemention.yml'),
         'utf8',
       )
       const data = {content: Buffer.from(fileContents).toString('base64')}

__tests__/main.test.ts

@@ -1,34 +1,69 @@
-import * as core from '@actions/core'
-import * as github from '@actions/github'
 import {GitHub} from '@actions/github/lib/utils'
 import {beforeEach, describe, expect, it, jest} from '@jest/globals'
 import {Api} from '@octokit/plugin-rest-endpoint-methods'
 import {randomUUID} from 'crypto'
-import {mockDeep} from 'jest-mock-extended'
+import {MockProxy, mock, mockDeep} from 'jest-mock-extended'
+
+import * as core from './moduleMocks/core'
+jest.unstable_mockModule('@actions/core', () => core)
+import * as origGithub from '@actions/github'
+const github = {
+  getOctokit: jest.fn<typeof origGithub.getOctokit>(),
+  context: mock<typeof origGithub.context>(),
+}
+jest.unstable_mockModule('@actions/github', () => github)
+
+function mockModuleAndInstance<T, CP extends unknown[]>(
+  modulePath: string,
+  ctor: new (...args: CP) => T,
+  exportName?: string,
+): [typeof ctor, MockProxy<T>] {
+  const instance = mock<T>()
+  const ctorMock = jest.fn((..._args: CP) => instance)
+  jest.unstable_mockModule(modulePath, () => ({
+    [exportName ?? ctor.name]: ctorMock,
+  }))
+  return [ctorMock, instance]
+}
 
 import {CommentRendererImpl} from '../src/comment-renderer'
+const [CommentRendererImplMock, commentRenderer] = mockModuleAndInstance(
+  '../src/comment-renderer',
+  CommentRendererImpl,
+)
+
 import {CommentUpserterImpl} from '../src/comment-upserter'
+const [CommentUpserterImplMock, commentUpserter] = mockModuleAndInstance(
+  '../src/comment-upserter',
+  CommentUpserterImpl,
+)
+
 import {ConfigurationReaderImpl} from '../src/configuration-reader'
+const [ConfigurationReaderImplMock, configurationReader] =
+  mockModuleAndInstance('../src/configuration-reader', ConfigurationReaderImpl)
+
 import {FilesChangedReaderImpl} from '../src/files-changed-reader'
-import {run} from '../src/main'
-import Runner from '../src/runner'
+const [FilesChangedReaderImplMock, filesChangedReader] = mockModuleAndInstance(
+  '../src/files-changed-reader',
+  FilesChangedReaderImpl,
+)
 
-jest.mock('@actions/core')
-jest.mock('@actions/github')
+import Runner from '../src/runner'
+const [RunnerMock, runner] = mockModuleAndInstance(
+  '../src/runner',
+  Runner,
+  'default',
+)
 
-jest.mock('../src/comment-renderer')
-jest.mock('../src/comment-upserter')
-jest.mock('../src/configuration-reader')
-jest.mock('../src/files-changed-reader')
-jest.mock('../src/runner')
+const {run} = await import('../src/main')
 
 describe('run', () => {
   const githubToken = randomUUID()
   let octokit: InstanceType<typeof GitHub>
   let octokitRest: Api['rest']
 
   beforeEach(() => {
-    jest.mocked(core).getInput.mockImplementation(input => {
+    core.getInput.mockImplementation(input => {
       if (input === 'githubToken') {
         return githubToken
       } else {
@@ -38,33 +73,32 @@ describe('run', () => {
 
     octokit = mockDeep<InstanceType<typeof GitHub>>()
     octokitRest = octokit.rest
-    jest.mocked(github).getOctokit.mockReturnValue(octokit)
+    github.getOctokit.mockReturnValue(octokit)
   })
 
   it('calls Runner.run', async () => {
     await run()
 
     expect(github.getOctokit).toHaveBeenCalledWith(githubToken)
-    expect(ConfigurationReaderImpl).toHaveBeenCalledWith(octokitRest)
-    expect(FilesChangedReaderImpl).toHaveBeenCalledWith(octokit)
-    expect(CommentUpserterImpl).toHaveBeenCalledWith(octokitRest)
-
-    expect(Runner).toHaveBeenCalledWith(
-      jest.mocked(ConfigurationReaderImpl).mock.instances[0],
-      jest.mocked(FilesChangedReaderImpl).mock.instances[0],
-      jest.mocked(CommentRendererImpl).mock.instances[0],
-      jest.mocked(CommentUpserterImpl).mock.instances[0],
-    )
+    expect(ConfigurationReaderImplMock).toHaveBeenCalledWith(octokitRest)
+    expect(FilesChangedReaderImplMock).toHaveBeenCalledWith(octokit)
+    expect(CommentRendererImplMock).toHaveBeenCalled()
+    expect(CommentUpserterImplMock).toHaveBeenCalledWith(octokitRest)
 
-    expect(jest.mocked(Runner).mock.instances[0].run).toHaveBeenCalledWith(
-      github.context,
+    expect(RunnerMock).toHaveBeenCalledWith(
+      configurationReader,
+      filesChangedReader,
+      commentRenderer,
+      commentUpserter,
     )
+
+    expect(runner.run).toHaveBeenCalledWith(github.context)
     expect(core.setFailed).not.toHaveBeenCalled()
   })
 
   describe('when an error is thrown', () => {
     it('sets the action status to failed', async () => {
-      jest.mocked(core).getInput.mockImplementation(() => {
+      core.getInput.mockImplementation(() => {
         throw new Error('getInput error')
       })
       await run()

__tests__/moduleMocks/core.ts

@@ -0,0 +1,10 @@
+import * as core from '@actions/core'
+import {jest} from '@jest/globals'
+
+export const debug = jest.fn<typeof core.debug>()
+export const error = jest.fn<typeof core.error>()
+export const getInput = jest.fn<typeof core.getInput>()
+export const info = jest.fn<typeof core.info>()
+export const setFailed = jest.fn<typeof core.setFailed>()
+export const setOutput = jest.fn<typeof core.setOutput>()
+export const warning = jest.fn<typeof core.warning>()

__tests__/runner.test.ts

@@ -31,7 +31,7 @@ describe('Runner', () => {
   let pullRequest: PullRequest
   const configuration: Configuration = yaml.load(
     fs.readFileSync(
-      path.join(__dirname, 'fixtures', 'codemention.yml'),
+      path.join(import.meta.dirname, 'fixtures', 'codemention.yml'),
       'utf8',
     ),
   ) as Configuration

eslint.config.mjs

@@ -61,7 +61,13 @@ export default defineConfig([
       'eslint-comments/no-use': 'off',
       'import/no-namespace': 'off',
       'no-unused-vars': 'off',
-      '@typescript-eslint/no-unused-vars': 'error',
+
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          argsIgnorePattern: '^_',
+        },
+      ],
 
       '@typescript-eslint/explicit-member-accessibility': [
         'error',

jest.config.js

@@ -1,11 +1,14 @@
 export default {
+  preset: 'ts-jest',
   clearMocks: true,
   moduleFileExtensions: ['js', 'ts'],
+  extensionsToTreatAsEsm: ['.ts'],
+  resolver: 'ts-jest-resolver',
   testMatch: ['**/*.test.ts'],
+  testPathIgnorePatterns: ['/node_modules/'],
   transform: {
-    '^.+\\.[jt]s$': 'ts-jest',
+    '^.+\\.ts$': ['ts-jest', {tsconfig: 'tsconfig.json', useESM: true}],
   },
-  transformIgnorePatterns: ['/node_modules/(?!(@octokit|before-after-hook|universal-user-agent)/)'],
   verbose: true,
   collectCoverageFrom: ['src/**/*.ts'],
   coverageThreshold: {