What is the purpose of reliability testing?

Reliability testing is primarily focused on ensuring that a system or application operates without failure for a designated period under specified conditions. This type of testing evaluates how dependable a system is over time, assessing its ability to maintain performance and functionality during regular use. The goal is to identify any potential failures or weaknesses that could lead to downtime or service interruptions, thereby ensuring a consistent user experience.

In contrast, the other options address different aspects of performance or user experience. Identifying aesthetic issues pertains to usability and design rather than reliability. Measuring user engagement involves understanding how users interact with the application, which is more related to user experience metrics. Optimizing database queries focuses on improving the efficiency of data retrieval, which does not directly relate to the system's reliability over time. Thus, the objective of reliability testing clearly aligns with ensuring failure-free operation for a specified period.