Finally, after all that refactoring, we get to test our invasion percolation program—although in fact, we spend more time discussing how to structure testing code than we do actually testing.

1. Introduction
2. The Grid
3. Aliasing
4. Randomness
5. Finding Neighbors
6. Resolving Ties
7. Assembling the Program
8. Bugs
9. Refactoring
10. Testing