Simplify Enterprise Testing With the Right Tools: Two Case Studies (Continued)

E-Load for Load Testing
Load testing involves stressing the system, and carefully watching for any difficulties, from minor issues like memory leaks to major problems like system failure. Empirix E-Load is the tool of choice here.

In the Block load test environment, controller modules load test agents: servers that create virtual users. In this way, the company can gradually simulate multiple users and observe the effects on resources (like memory) of having more users engaging the system. "We have performance targets for different numbers of concurrent users, so that users don't have to wait more than an acceptable time for, say, a Web page to load," explains Deloney. The testers keep increasing the load on the system, while looking for a fall-off in response time.

Block tries to make its tests as much like real demands as possible. "It can be difficult to match the test cases to real life," advises Deloney. To help make that match as faithful as possible, Block uses OneSight and e-Manager to keep an eye on the real system. These tools unobtrusively note the conditions under real use, including the heaviest day or hour, most-demanded pages, and typical and maximum numbers of users.

This harvested data gives testers an idea of the limits of demand that the real system experiences. Armed with this information, the testers can then design tests that more realistically match what the actual systems face. Sometimes they conduct their tests on genuine production equipment, and sometimes they use a subset of the equipment designed to represent a specific percentage of production capacity.