chore: add browser example test (#846)

examples/libp2p-in-the-browser/test.js

@@ -0,0 +1,52 @@
+'use strict'
+
+const execa = require('execa')
+const { chromium } = require('playwright');
+
+async function run() {
+  let url = ''
+  const proc = execa('parcel', ['./index.html'], {
+    preferLocal: true,
+    localDir: __dirname,
+    cwd: __dirname,
+    all: true
+  })
+
+  proc.all.on('data', async (chunk) => {
+    /**@type {string} */
+    const out = chunk.toString()
+
+    if (out.includes('Server running at')) {
+      url = out.replace('Server running at ', '')
+    }
+
+    if (out.includes('✨  Built in ')) {
+      try {
+        const browser = await chromium.launch();
+        const page = await browser.newPage();
+        await page.goto(url);
+        await page.waitForFunction(selector => document.querySelector(selector).innerText === 'libp2p started!', '#status')
+        await page.waitForFunction(
+          selector => {
+            const text = document.querySelector(selector).innerText
+            return text.includes('libp2p id is') &&
+              text.includes('Found peer') &&
+              text.includes('Connected to')
+          },
+          '#output',
+          { timeout: 5000 }
+        )
+        await browser.close();
+
+      } catch (err) {
+        console.error(err)
+        process.exit(1)
+      } finally {
+        proc.cancel()
+      }
+    }
+  })
+
+}
+
+module.exports = run