Summary
In this chapter, you have learned about testing error conditions within an application. These tests are designed to cause failures, but they should be caught early and be as limited as possible by expecting the issues and handling them gracefully. Unexpected errors, especially ones that persist over time, cause a poor user experience, are difficult to debug, and may cause other, much worse problems.
To test error cases, you should push the system beyond its specified limits, try the timeouts on messages, trigger communication failures with network errors, inject invalid fields, and fuzz messages with random data.
Carefully consider the priority of the error case testing. It is a lower priority than the rest of functional testing, which guarantees a new feature or application is working in usual cases. Public interfaces or mission-critical applications must be resilient to errors and perform well during expected operations. Even for less critical applications, if you don...
