fix(local): allow local driver provider to use gecko driver from config

- Add gecko driver as configuration option to be used in the local
  driver provider.
- Nit fixes to use string[] over Array<string> in the configParser.ts
- Add functionality to addDefaultBinaryLocs_ to use the geckoDriver
  value set in the config or to check locally in the
  webdriver-manager/selenium folder

closes angular#4408 and closes angular#4411.

lib/config.ts

@@ -66,16 +66,22 @@ export interface Config {
     jvmArgs?: string[];
   };
   /**
-   * ChromeDriver location is used to help find the chromedriver binary.
-   * This will be passed to the Selenium jar as the system property
-   * webdriver.chrome.driver. If null, Selenium will attempt to find
-   * ChromeDriver using PATH.
+   * ChromeDriver location is used to help find the chromedriver binary. This will be passed to the
+   * Selenium jar as the system property webdriver.chrome.driver. If the value is not set when
+   * launching locally, it will use the default values downloaded from webdriver-manager.
    *
    * example:
    * chromeDriver: './node_modules/webdriver-manager/selenium/chromedriver_2.20'
    */
   chromeDriver?: string;
 
+  /**
+   * geckoDriver location is used to help find the gecko binary. This will be passed to the Selenium
+   * jar as the system property webdriver.gecko.driver. If the value is not set when launching
+   * locally, it will use the default values downloaded from webdriver-manager.
+   */
+  geckoDriver?: string;
+
   // ---- 2. To connect to a Selenium Server which is already running ----------
 
   /**

lib/configParser.ts

@@ -55,9 +55,9 @@ export class ConfigParser {
    * @return {Array} The resolved file paths.
    */
   public static resolveFilePatterns(
-      patterns: Array<string>|string, opt_omitWarnings?: boolean,
-      opt_relativeTo?: string): Array<string> {
-    let resolvedFiles: Array<string> = [];
+      patterns: string[]|string, opt_omitWarnings?: boolean,
+      opt_relativeTo?: string): string[] {
+    let resolvedFiles: string[] = [];
     let cwd = opt_relativeTo || process.cwd();
 
     patterns = (typeof patterns === 'string') ? [patterns] : patterns;
@@ -82,8 +82,8 @@ export class ConfigParser {
    *
    * @return {Array} An array of globs locating the spec files
    */
-  static getSpecs(config: Config): Array<string> {
-    let specs: Array<string> = [];
+  static getSpecs(config: Config): string[] {
+    let specs: string[] = [];
     if (config.suite) {
       config.suite.split(',').forEach((suite) => {
         let suiteList = config.suites ? config.suites[suite] : null;
@@ -115,12 +115,12 @@ export class ConfigParser {
   private addConfig_(additionalConfig: any, relativeTo: string): void {
     // All filepaths should be kept relative to the current config location.
     // This will not affect absolute paths.
-    ['seleniumServerJar', 'chromeDriver', 'onPrepare', 'firefoxPath', 'frameworkPath'].forEach(
-        (name) => {
-          if (additionalConfig[name] && typeof additionalConfig[name] === 'string') {
-            additionalConfig[name] = path.resolve(relativeTo, additionalConfig[name]);
-          }
-        });
+    ['seleniumServerJar', 'chromeDriver', 'firefoxPath', 'frameworkPath',
+      'geckoDriver', 'onPrepare'].forEach((name: string) => {
+        if (additionalConfig[name] && typeof additionalConfig[name] === 'string') {
+          additionalConfig[name] = path.resolve(relativeTo, additionalConfig[name]);
+        }
+      });
 
     merge_(this.config_, additionalConfig);
   }
@@ -206,10 +206,10 @@ let makeArray = function(item: any): any {
  * Adds to an array all the elements in another array without adding any
  * duplicates
  *
- * @param {Array<string>} dest The array to add to
- * @param {Array<string>} src The array to copy from
+ * @param {string[]} dest The array to add to
+ * @param {string[]} src The array to copy from
  */
-let union = function(dest: Array<string>, src: Array<string>): void {
+let union = function(dest: string[], src: string[]): void {
   let elems: any = {};
   for (let key in dest) {
     elems[dest[key]] = true;

lib/driverProviders/local.ts

@@ -86,6 +86,37 @@ export class Local extends DriverProvider {
         }
       }
     }
+
+    if (this.config_.capabilities.browserName === 'firefox') {
+      if (!this.config_.geckoDriver) {
+        logger.debug(
+          'Attempting to find the gecko driver binary in the default ' +
+          'location used by webdriver-manager');
+
+        try {
+          let updateJson = path.resolve(SeleniumConfig.getSeleniumDir(), 'update-config.json');
+          let updateConfig = JSON.parse(fs.readFileSync(updateJson).toString());
+          this.config_.geckoDriver = updateConfig.gecko.last;
+        } catch (err) {
+          throw new BrowserError(
+              logger,
+              'No update-config.json found. ' +
+                  'Run \'webdriver-manager update\' to download binaries.');
+        }
+      }
+
+      // Check if file exists, if not try .exe or fail accordingly
+      if (!fs.existsSync(this.config_.geckoDriver)) {
+        if (fs.existsSync(this.config_.geckoDriver + '.exe')) {
+          this.config_.geckoDriver += '.exe';
+        } else {
+          throw new BrowserError(
+              logger,
+              'Could not find gecko driver at ' + this.config_.geckoDriver +
+                  '. Run \'webdriver-manager update\' to download binaries.');
+        }
+      }
+    }
   }
 
   /**