This chapter has given us a number of angles to approach two of the most important parts of building a successful application: fixing issues and adding polish. While explicit customer requirements form the main body of our work, we should always strive to make sure that our projects are performant and as bug-free as possible.

The Chrome Developer Tools are an invaluable weapon in our arsenal. By opening a window in the otherwise dark world of debugging and performance, we can take educated steps to quickly resolve issues. Stepping through our own code and that of the Ext JS framework becomes significantly easier with the power of breakpoints and the call stack explorer.

In the next chapter, we'll take our final step to building a well-rounded and robust application. While we are constantly working to build the best architecture we can, automated testing can provide a level of reassurance that takes the solidity of our work to the next level.

Code changes and refactoring can be done with confidence when our test suite can tell us if we've broken something with our latest amendments. Integration tests can provide assurances that our final application meets customer requirements and unit tests can encourage separation of code and ensure that our business logic is sound.

In the next chapter, we'll look into a variety of ways to implement these ideas and more.