feat(saucelabs): add sauceRegion support for eu datacenters (#5083)

This change allows user to define the backend region from sauce via the `sauceRegion` property, e.g. 

```js
    sauceUser: process.env.SAUCE_USERNAME,
    sauceKey: process.env.SAUCE_ACCESS_KEY,
    sauceRegion: 'eu',
```

Will run the test against `https://ondemand.eu-central-1.saucelabs.com:443/wd/hub/.`

```js
    sauceUser: process.env.SAUCE_USERNAME,
    sauceKey: process.env.SAUCE_ACCESS_KEY,
    sauceRegion: 'us',

    // the default
    sauceUser: process.env.SAUCE_USERNAME,
    sauceKey: process.env.SAUCE_ACCESS_KEY,
```

Will run the test against https://ondemand.saucelabs.com:443/wd/hub/

lib/config.ts

@@ -136,6 +136,13 @@ export interface Config {
    * ignored. The tests will be run remotely using Sauce Labs.
    */
   sauceKey?: string;
+  /**
+   * If you run your tests on SauceLabs you can specify the region you want to run your tests
+   * in via the `sauceRegion` property. Available short handles for regions are:
+   * us: us-west-1 (default)
+   * eu: eu-central-1
+   */
+  sauceRegion?: string;
   /**
    * Use sauceAgent if you need custom HTTP agent to connect to saucelabs.com APIs.
    * This is needed if your computer is behind a corporate proxy.

lib/driverProviders/sauce.ts

@@ -14,6 +14,10 @@ import {Logger} from '../logger';
 import {DriverProvider} from './driverProvider';
 
 const SauceLabs = require('saucelabs');
+const SAUCE_REGIONS: {[key: string]: string} = {
+  'us': '',  // default endpoint
+  'eu': 'eu-central-1.'
+};
 
 let logger = new Logger('sauce');
 export class Sauce extends DriverProvider {
@@ -55,6 +59,7 @@ export class Sauce extends DriverProvider {
   protected setupDriverEnv(): q.Promise<any> {
     let deferred = q.defer();
     this.sauceServer_ = new SauceLabs({
+      hostname: this.getSauceEndpoint(this.config_.sauceRegion),
       username: this.config_.sauceUser,
       password: this.config_.sauceKey,
       agent: this.config_.sauceAgent,
@@ -66,8 +71,9 @@ export class Sauce extends DriverProvider {
     let protocol = this.config_.sauceSeleniumUseHttp ? 'http://' : 'https://';
     let auth = protocol + this.config_.sauceUser + ':' + this.config_.sauceKey + '@';
     this.config_.seleniumAddress = auth +
-        (this.config_.sauceSeleniumAddress ? this.config_.sauceSeleniumAddress :
-                                             'ondemand.saucelabs.com:443/wd/hub');
+        (this.config_.sauceSeleniumAddress ?
+             this.config_.sauceSeleniumAddress :
+             `ondemand.${this.getSauceEndpoint(this.config_.sauceRegion)}:443/wd/hub`);
 
     // Append filename to capabilities.name so that it's easier to identify
     // tests.
@@ -82,4 +88,17 @@ export class Sauce extends DriverProvider {
     deferred.resolve();
     return deferred.promise;
   }
+
+  /**
+   * Get the Sauce Labs endpoint
+   * @private
+   * @param {string} region
+   * @return {string} The endpoint that needs to be used
+   */
+  private getSauceEndpoint(region: string): string {
+    const dc = region ?
+        typeof SAUCE_REGIONS[region] !== 'undefined' ? SAUCE_REGIONS[region] : (region + '.') :
+        '';
+    return `${dc}saucelabs.com`;
+  }
 }