test: update karma runner (#2524)

* test: update karma runner

* fix: Promise polyfill for testrunner

tests/karma.ts

@@ -0,0 +1,32 @@
+import {screenshotApp, corsApp} from './server';
+import {Server} from 'http';
+import {config as KarmaConfig, Server as KarmaServer, TestResults} from 'karma';
+import * as path from 'path';
+
+const karmaTestRunner = (): Promise<void> =>
+    new Promise<void>((resolve, reject) => {
+        const karmaConfig = KarmaConfig.parseConfig(path.resolve(__dirname, '../karma.conf.js'), {});
+        const server = new KarmaServer(karmaConfig, (exitCode: number) => {
+            if (exitCode > 0) {
+                reject(`Karma has exited with ${exitCode}`);
+            } else {
+                resolve();
+            }
+        });
+        server.on('run_complete', (_browsers: any, _results: TestResults) => {
+            server.stop();
+        });
+        server.start();
+    });
+const servers: Server[] = [];
+
+servers.push(screenshotApp.listen(8000));
+servers.push(corsApp.listen(8081));
+
+karmaTestRunner().then(() => {
+    servers.forEach(server => server.close());
+}).catch(e => {
+    console.error(e);
+    process.exit(1);
+});
+