refactor(e2e-test): wrap the test registration

packages/core/scripts/e2e-test-runner.js

@@ -1,9 +1,9 @@
+'use strict';
+
 const glob = require('glob');
 const Mocha = require('mocha');
 const path = require('path');
 
-const mocha = new Mocha();
-
 function startDevServer() {
   const server = require('@stencil/dev-server/dist'); // TODO: fix after stencil-dev-server PR #16 is merged
   const cmdArgs = ['--config', path.join(__dirname, '../stencil.config.js'), '--no-open'];
@@ -25,11 +25,16 @@ function getTestFiles() {
 }
 
 (async () => {
+  const mocha = new Mocha({
+    timeout: 5000,
+    slow: 2000
+  });
+
   const devServer = await startDevServer();
+  // process.env.takeScreenshots = true;
 
   const files = await getTestFiles();
   files.forEach(f => mocha.addFile(f));
-
   mocha.run(function(failures) {
     process.on('exit', function() {
       process.exit(failures); // exit with non-zero status if there were failures

packages/core/scripts/register-e2e-test.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const fs = require('fs');
+const webdriver = require('selenium-webdriver');
+
+function takeScreenshot(driver, name) {
+  return driver.takeScreenshot().then(function(data) {
+    var base64Data = data.replace(/^data:image\/png;base64,/, '');
+    fs.writeFile(`${name}.png`, base64Data, 'base64', function(err) {
+      if (err) console.log(err);
+    });
+  });
+}
+
+function allowForAnnimation() {
+  return new Promise((resolve, reject) => {
+    setTimeout(function() {
+      resolve();
+    }, 300);
+  });
+}
+
+function registerE2ETest(desc, tst) {
+  it(desc, async () => {
+    const driver = new webdriver.Builder().forBrowser('chrome').build();
+    await tst(driver);
+    if (process.env.takeScreenshots) {
+      await allowForAnnimation();
+      takeScreenshot(driver, desc);
+    }
+    return driver.quit();
+  });
+}
+
+module.exports = registerE2ETest;