[js] Preliminary support for marionette.

Marionette may be enabled through the API, or by setting the SELENIUM_MARIONETTE
environment variable. When enabled, seleniuv-webdriver will default to looking
for Firefox's Developer Edition instead of the stable channel (since marionette
doesn't support stable channel yet). Users can still manually configure the path
to Firefox through the API.

I still need to work through the test suite to identify features that don't work
in marionette (lack of profile support is one known issue)

Author: jleyba

javascript/node/selenium-webdriver/CHANGES.md

@@ -2,6 +2,10 @@
 
 ### Change Summary
 
+* Added preliminary support for Marionette, Mozilla's WebDriver implementation
+   for Firefox. Marionette may be enabled via the API,
+   `firefox.Options#useMarionette`, or by setting the `SELENIUM_MARIONETTE`
+   environment variable.
 * Moved all logic for parsing and interpreting responses from the remote end
    into the individual `command.Executor` implementations.
 * For consistency with the other Selenium language bindings,

javascript/node/selenium-webdriver/firefox/binary.js

@@ -47,19 +47,26 @@ const NO_FOCUS_LIB_AMD64 = isDevMode ?
 
 const X_IGNORE_NO_FOCUS_LIB = 'x_ignore_nofocus.so';
 
-var foundBinary = null;
+
+let foundBinary = null;
+let foundDevBinary = null;
 
 
 /**
  * Checks the default Windows Firefox locations in Program Files.
+ *
+ * @param {boolean=} opt_dev Whether to find the Developer Edition.
  * @return {!Promise<?string>} A promise for the located executable.
  *     The promise will resolve to {@code null} if Firefox was not found.
  */
-function defaultWindowsLocation() {
+function defaultWindowsLocation(opt_dev) {
   var files = [
     process.env['PROGRAMFILES'] || 'C:\\Program Files',
     process.env['PROGRAMFILES(X86)'] || 'C:\\Program Files (x86)'
   ].map(function(prefix) {
+    if (opt_dev) {
+      return path.join(prefix, 'Firefox Developer Edition\\firefox.exe');
+    }
     return path.join(prefix, 'Mozilla Firefox\\firefox.exe');
   });
   return io.exists(files[0]).then(function(exists) {
@@ -72,31 +79,47 @@ function defaultWindowsLocation() {
 
 /**
  * Locates the Firefox binary for the current system.
- * @return {!promise.Promise.<string>} A promise for the located binary. The
- *     promise will be rejected if Firefox cannot be located.
+ *
+ * @param {boolean=} opt_dev Whether to find the Developer Edition. This only
+ *     used on Windows and OSX.
+ * @return {!Promise<string>} A promise for the located binary. The promise will
+ *     be rejected if Firefox cannot be located.
  */
-function findFirefox() {
-  if (foundBinary) {
+function findFirefox(opt_dev) {
+  if (opt_dev && foundDevBinary) {
+    return foundDevBinary;
+  }
+
+  if (!opt_dev && foundBinary) {
     return foundBinary;
   }
 
+  let found;
   if (process.platform === 'darwin') {
-    var osxExe =  '/Applications/Firefox.app/Contents/MacOS/firefox-bin';
-    foundBinary = io.exists(osxExe).then(function(exists) {
-      return exists ? osxExe : null;
-    });
+    let exe = opt_dev
+        ? '/Applications/FirefoxDeveloperEdition.app/Contents/MacOS/firefox-bin'
+        : '/Applications/Firefox.app/Contents/MacOS/firefox-bin';
+    found = io.exists(exe).then(exists => exists ? exe : null);
+
   } else if (process.platform === 'win32') {
-    foundBinary = defaultWindowsLocation();
+    found = defaultWindowsLocation(opt_dev);
+
   } else {
-    foundBinary = promise.fulfilled(io.findInPath('firefox'));
+    found = Promise.resolve(io.findInPath('firefox'));
   }
 
-  return foundBinary = foundBinary.then(function(found) {
+  found = found.then(found => {
     if (found) {
       return found;
     }
     throw Error('Could not locate Firefox on the current system');
   });
+
+  if (opt_dev) {
+    return foundDevBinary = found;
+  } else {
+    return foundBinary = found;
+  }
 }
 
 
@@ -136,12 +159,17 @@ function installNoFocusLibs(profileDir) {
  * Provides a mechanism to configure and launch Firefox in a subprocess for
  * use with WebDriver.
  *
+ * If created _without_ a path for the Firefox binary to use, this class will
+ * attempt to find Firefox when {@link #launch()} is called. For OSX and
+ * Windows, this class will look for Firefox in the current platform's default
+ * installation location (e.g. /Applications/Firefox.app on OSX). For all other
+ * platforms, the Firefox executable must be available on your system `PATH`.
+ *
  * @final
  */
 class Binary {
   /**
-   * @param {string=} opt_exe Path to the Firefox binary to use. If not
-   *     specified, will attempt to locate Firefox on the current system.
+   * @param {string=} opt_exe Path to the Firefox binary to use.
    */
   constructor(opt_exe) {
     /** @private {(string|undefined)} */
@@ -157,6 +185,9 @@ class Binary {
       MOZ_NO_REMOTE: '1',
       NO_EM_RESTART: '1'
     });
+
+    /** @private {boolean} */
+    this.devEdition_ = false;
   }
 
   /**
@@ -174,6 +205,34 @@ class Binary {
     }
   }
 
+  /**
+   * Specifies whether to use Firefox Developer Edition instead of the normal
+   * stable channel. Setting this option has no effect if this instance was
+   * created with a path to a specific Firefox binary.
+   *
+   * This method has no effect on Unix systems where the Firefox application
+   * has the same (default) name regardless of version.
+   *
+   * @param {boolean=} opt_use Whether to use the developer edition. Defaults to
+   *     true.
+   */
+  useDevEdition(opt_use) {
+    this.devEdition_ = opt_use === undefined || !!opt_use;
+  }
+
+  /**
+   * Returns a promise for the Firefox executable used by this instance. The
+   * returned promise will be immediately resolved if the user supplied an
+   * executable path when this instance was created. Otherwise, an attempt will
+   * be made to find Firefox on the current system.
+   *
+   * @return {!promise.Promise<string>} a promise for the path to the Firefox
+   *     executable used by this instance.
+   */
+  locate() {
+    return promise.fulfilled(this.exe_ || findFirefox(this.devEdition_));
+  }
+
   /**
    * Launches Firefox and returns a promise that will be fulfilled when the
    * process terminates.
@@ -187,7 +246,7 @@ class Binary {
 
     let args = ['-foreground'].concat(this.args_);
 
-    return promise.when(this.exe_ || findFirefox(), function(firefox) {
+    return this.locate().then(function(firefox) {
       if (process.platform === 'win32' || process.platform === 'darwin') {
         return exec(firefox, {args: args, env: env});
       }
@@ -209,7 +268,7 @@ class Binary {
    *     representation.
    */
   [Symbols.serialize]() {
-    return promise.fulfilled(this.exe_ || findFirefox());
+    return this.locate();
   }
 }