env variables doc

README.md

@@ -228,8 +228,13 @@ const bot = new Wechaty(options)
 
 options:
 
-1. `session`: session name. if a session name is provided, the login status will be saved to it, and automatically restored on next time of wechaty start(restart).
+1. `session`(OPTIONAL): session name. if a session name is provided, the login status will be saved to it, and automatically restored on next time of wechaty start(restart).
     * can be set by environment variable: `WECHATY_SESSION`
+1. `head`(OPTIONAL): specify the browser name for webdriver.
+    * can be set by environment variable: `WECHATY_HEAD`
+    * values:
+        * `phantomjs`: it's the default behaviour if head is not set.
+        * `chrome`
 
 ### Wechaty.init()
 Initialize the bot, return Promise.

test/webdriver-spec.js

@@ -13,8 +13,9 @@ const By = WebDriver.By
 
 const PuppetWebBrowser  = require('../src/puppet-web-browser')
 const PuppetWebBridge   = require('../src/puppet-web-bridge')
-const PORT = 58788
-const HEAD = 'chrome' // undefined
+
+const PORT = process.env.WECHATY_PORT || 58788
+const HEAD = process.env.WECHATY_HEAD || false
 
 function driverProcessNum() {
   return new Promise((resolve, reject) => {