Testing a large-scale, real-life commercial software application is a very challenging task due to the constant changes in the software, the involvement of multiple programmers and testers, and a large amount of code. Integrating testing with development can help find program bugs at an earlier stage and hence reduce the overall cost. In this paper, we report our experience on how to apply eXVantage^1 (a tool suite for code coverage testing, debugging, performance profiling, etc.) to a large, complex Java application at the implementation and unit testing phases in Avaya. Our results suggest that programmers and testers can benefit from using eXVantage to monitor the testing process, gain confidence on the quality of their software, detect bugs which are otherwise difficult to reveal, and identify performance bottlenecks in terms of which part of code is most frequently executed.