some frontend unit tests

test/frontend/runner.js

@@ -0,0 +1,63 @@
+/* eslint-disable no-undef, no-process-exit */
+const fs = require('fs');
+const path = require('path');
+const mkdirp = require('mkdirp');
+const puppeteer = require('puppeteer');
+const webpack = require('webpack');
+const config = require('../../webpack.config');
+const middleware = require('webpack-dev-middleware');
+const express = require('express');
+const devRoutes = require('../../server/dev');
+const app = express();
+
+const wpm = middleware(webpack(config), { logLevel: 'silent' });
+app.use(wpm);
+devRoutes(app, { middleware: wpm });
+
+function onConsole(msg) {
+  // excluding 'log' because mocha uses it to write the json output
+  if (msg.type() !== 'log') {
+    console.error(msg.text());
+  }
+}
+
+const server = app.listen(async function() {
+  let exitCode = -1;
+  const browser = await puppeteer.launch();
+  try {
+    const page = await browser.newPage();
+    page.on('console', onConsole);
+    page.on('pageerror', console.log.bind(console));
+    await page.goto(`http://127.0.0.1:${server.address().port}/test`);
+    await page.waitFor(() => typeof runner.testResults !== 'undefined', {
+      timeout: 5000
+    });
+    const results = await page.evaluate(() => runner.testResults);
+    const coverage = await page.evaluate(() => __coverage__);
+    if (coverage) {
+      const dir = path.resolve(__dirname, '../../.nyc_output');
+      mkdirp.sync(dir);
+      fs.writeFileSync(
+        path.resolve(dir, 'frontend.json'),
+        JSON.stringify(coverage)
+      );
+    }
+    const stats = results.stats;
+    exitCode = stats.failures;
+    console.log(`${stats.passes} passing (${stats.duration}ms)\n`);
+    if (stats.failures) {
+      console.log('Failures:\n');
+      for (const f of results.failures) {
+        console.log(`${f.fullTitle}`);
+        console.log(` ${f.err.stack}\n`);
+      }
+    }
+  } catch (e) {
+    console.log(e);
+  } finally {
+    browser.close();
+    server.close(() => {
+      process.exit(exitCode);
+    });
+  }
+});