Use ESM (#758)

* Use ESM

* Fix

jest.config.js

@@ -1,7 +1,9 @@
-module.exports = {
-  preset: 'ts-jest',
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+export default {
+  preset: 'ts-jest/presets/default-esm',
   clearMocks: true,
-  testEnvironment: 'node',
-  testMatch: ['**/*.test.ts'],
-  verbose: true
+  // https://kulshekhar.github.io/ts-jest/docs/guides/esm-support/
+  moduleNameMapper: {
+    '^(\\.{1,2}/.*)\\.js$': '$1',
+  },
 }

package.json

@@ -6,6 +6,7 @@
     "build": "ncc build --source-map --license licenses.txt src/main.ts",
     "test": "jest"
   },
+  "type": "module",
   "dependencies": {
     "@actions/core": "1.10.1"
   },

src/main.ts

@@ -1,5 +1,5 @@
 import * as core from '@actions/core'
-import { run } from './run'
+import { run } from './run.js'
 
 const main = async (): Promise<void> => {
   await run({

tests/run.test.ts

@@ -1,4 +1,4 @@
-import { run } from '../src/run'
+import { run } from '../src/run.js'
 
 test('run successfully', async () => {
   await expect(run({ name: 'foo' })).resolves.toBeUndefined()