Base support for forking a browser.

Still need to add snapshooting the cookies, storage, cache and history.

spec/browser-spec.coffee

@@ -313,4 +313,24 @@ vows.describe("Browser").addBatch(
         assert.match browser.document.title, /colorDepth=24/
         assert.match browser.document.title, /pixelDepth=24/
 
+  "fork":
+    zombie.wants "http://localhost:3003/living"
+      "new browser":
+        topic: (browser)->
+          forked = browser.fork()
+          [forked, browser]
+        "should have two browser objects": (browsers)->
+          [forked, browser] = browsers
+          assert.isNotNull forked
+          assert.isNotNull browser
+        "should not be the same object": (browsers)->
+          [forked, browser] = browsers
+          assert.notStrictEqual browser, forked
+        "should navigate independently": (browsers)->
+          [forked, browser] = browsers
+          forked.visit "http://localhost:3003/dead"
+          forked.wait()
+          assert.equal browser.location.href, "http://localhost:3003/living#/"
+          assert.equal forked.location, "http://localhost:3003/dead"
+
 ).export(module)

src/zombie/browser.coffee

@@ -63,6 +63,16 @@ class Browser extends require("events").EventEmitter
         else
           throw "I don't recognize the option #{k}"
 
+    # Fork
+    # ----
+
+    # ### browser.fork() => Browser
+    #
+    # Return a new browser with a snapshot of this browser's data.
+    # Any changes to the forked browser's state do not affect this browser.
+    this.fork = ->
+      forked = new Browser()
+      return forked
 
     # Windows
     # -------