configure jest suite to test esm

__tests__/esm.mjs

@@ -0,0 +1,2 @@
+import '../dist/index.js'
+it("ok", ()=>{})

__tests__/index.ts

@@ -1,10 +1,10 @@
-import Index, {type} from '../src/index';
-import * as assert from 'assert';
+import Index, { type } from '../src/index';
+
 
 describe('', () => {
 	it('', () => {
-		assert.strictEqual(new Index().constructor.name, 'Index');
-		assert.strictEqual(type, 'typescript');
+		expect(new Index().constructor.name).toBe('Index');
+		expect(type).toBe('typescript')
 	});
 
 });

dist/index.d.ts

@@ -1,2 +1,5 @@
-export {};
+export default class Index {
+    constructor();
+}
+export declare const type = "typescript";
 //# sourceMappingURL=index.d.ts.map

dist/index.js

@@ -1,2 +1,5 @@
-"use strict";
-Object.defineProperty(exports, "__esModule", { value: true });
+export default class Index {
+    constructor() {
+    }
+}
+export const type = 'typescript';

jest.config.esm.json

@@ -0,0 +1,3 @@
+{
+  "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.m?js$"
+}

jest.config.json

@@ -0,0 +1,4 @@
+{
+	"preset": "ts-jest",
+	"resolver": "jest-ts-webcompat-resolver"
+}

package.json

@@ -2,18 +2,22 @@
   "scripts": {
     "compile": "tsc --project tsconfig.json",
     "test": "jest",
+    "test:esm": "node --experimental-vm-modules node_modules/jest/bin/jest.js --config=jest.config.esm.json",
     "mocha-test": "ts-mocha test/*"
   },
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "devDependencies": {
     "@types/jest": "latest",
+    "@types/node": "latest",
     "@typescript-eslint/eslint-plugin": "latest",
     "@typescript-eslint/parser": "latest",
     "eslint": "latest",
     "jest": "latest",
+    "jest-ts-webcompat-resolver": "latest",
     "ts-jest": "latest",
     "ts-mocha": "latest",
     "typescript": "latest"
-  }
+  },
+  "type": "module"
 }