Warning
It's important to understand that a load test is only a simulation. This implies that despite all the possible and imaginable tests, you don't have a 100% guarantee that everything will proceed smoothly in production. There will always be an unplanned case (failure of a part of the system, unanticipated customer action, and so on).
To increase the chances of success, it's important to also work on the architecture (design for failure and so on) and the deployment process (canary release and so on).
Despite this, a load test is important to:
- Put into production the healthiest application
- Fine-tune as much as possible the architecture and application
- Reproduce a performance or multithreading issue detected in production to fix it
- Give business an idea of future response times when a new application goes live
- Anticipate Sales period
- Understand the weak points of the application
- Validate/improve monitoring (metrics, tools, dashboards, and so on...