oncletom/html-game-of-life — comment on commit 9f334f2b1e8b797715caf269de5bafa3a053428d
File:  line 0
By jeanphix:

You can't execute method calls on object backed by casper (via getGlobal here), methods have to be called inside webkit frame.
The Grid object inside the callable passed to assertEval is the one inside current frame.

So here you can simply remove "var Grid = self.getGlobal("Grid");"