Post-build hook that tests the built ECMAScript Module

closes sinonjs#1805

package.json

@@ -20,17 +20,20 @@
     "test-coverage": "mochify --recursive -R dot --grep WebWorker --invert --plugin [ proxyquire-universal ] --plugin [ mochify-istanbul --exclude '**/test/**' --report text --report lcovonly --dir ./coverage ] test/**.js",
     "test-cloud": "npm run test-headless -- --wd",
     "test-webworker": "mochify --https-server 8080 test/webworker/webworker-support-assessment.js",
-    "test-es-module": "mocha -r esm test/es2015/module-support-assessment-test.mjs",
-    "test": "run-s test-node test-headless test-webworker test-es-module",
+    "test-esm": "mocha -r esm test/es2015/module-support-assessment-test.mjs",
+    "test-esm-bundle": "node test/es2015/check-esm-bundle-is-runnable.js",
+    "test": "run-s test-node test-headless test-webworker test-esm",
     "check-dependencies": "dependency-check package.json --unused --no-dev --ignore-module coveralls --ignore-module esm",
-    "build": "node ./build.js",
+    "build": "run-p build-*",
+    "build-bundle": "node ./build.js",
     "build-esm": "rollup -c",
     "lint": "run-p lint-js lint-markdown",
     "lint-js": "eslint '**/*.{js,mjs}'",
     "lint-markdown": "find docs -type f -name '*.md' ! -name 'changelog.md' | xargs markdownlint",
     "precommit": "lint-staged",
     "pretest-webworker": "npm run build",
     "prebuild": "rimraf pkg && npm run check-dependencies",
+    "postbuild": "run-s test-esm-bundle",
     "prepublishOnly": "npm run build",
     "preversion": "./scripts/preversion.sh",
     "postversion": "./scripts/postversion.sh"
@@ -69,6 +72,7 @@
     "proxyquire": "^1.8.0",
     "proxyquire-universal": "^1.0.8",
     "proxyquireify": "^3.2.1",
+    "puppeteer": "^1.4.0",
     "rimraf": "^2.5.3",
     "rollup": "^0.59.3",
     "rollup-plugin-commonjs": "^9.1.3",

test/es2015/.eslintrc.yml

@@ -1,2 +1,3 @@
 parserOptions:
   sourceType: module
+  ecmaVersion: 2017

test/es2015/check-esm-bundle-is-runnable.js

@@ -0,0 +1,71 @@
+/* eslint-disable no-process-exit */
+const puppeteer = require("puppeteer");
+
+const http = require("http");
+const fs = require("fs");
+const port = 3876;
+
+const htmlWithModuleScript = `
+<script type="module">
+import sinon from '/sinon-esm.js';
+
+const assert = (result) => { if(!result) throw new Error(); };
+
+try {
+    const stub = sinon.stub().returns(42);
+    assert(42 === stub());
+    console.log('sinon-result:works');
+} catch(err) {
+    console.log('sinon-result:fails');
+}
+</script>
+`;
+
+// start server where our built sinon esm bundle resides
+process.chdir(`${__dirname}/../../pkg/`);
+const sinonModule = fs.readFileSync("./sinon-esm.js");
+
+async function evaluatePageContent() {
+    const browser = await puppeteer.launch();
+    const page = await browser.newPage();
+
+    page.on("error", function (err) {
+        throw err;
+    });
+
+    // our "assertion framework" :)
+    page.on("console", function (msg) {
+        var text = msg.text();
+
+        if (text.startsWith("sinon-result:works")) {
+            browser.close();
+            process.exit(0);
+        } else if (text.startsWith("sinon-result:fails")) {
+            browser.close();
+            process.exit(1);
+        }
+    });
+
+    await page.goto("http://localhost:3876");
+}
+
+const app = http.createServer((req, res) => {
+    let body, type;
+
+    if (req.url.match(/sinon-esm\.js/)) {
+        body = sinonModule;
+        type = "application/javascript";
+    } else {
+        body = htmlWithModuleScript;
+        type = "text/html";
+    }
+
+    const headers = {
+        "Content-Length": Buffer.byteLength(body),
+        "Content-Type": type
+    };
+    res.writeHead(200, headers);
+    res.end(body);
+});
+
+app.listen(port, evaluatePageContent);