Fault Injection Testing is a technique where faults (errors or failures) are deliberately introduced into a system to evaluate its robustness, error-handling mechanisms, and failure recovery processes.
Purpose:
- To ensure that the system can handle unexpected failures gracefully.
- To identify weaknesses and improve system reliability.
- To simulate real-world failure scenarios in a controlled manner.
Types of Fault Injection Testing:
Hardware Fault Injection
- Introduces physical hardware failures (e.g., disconnecting a network cable, removing a hard drive).
- Example: Unplugging a server to test system failover mechanisms.
Software Fault Injection
- Injects faults into the software (e.g., modifying code, corrupting memory).
- Example: Intentionally causing a memory leak to see if the system crashes.
Network Fault Injection
- Simulates network issues like packet loss, latency, or disconnections.
- Example: Using tools to simulate a slow or unstable network connection.
Stress Fault Injection
- Overloads system resources to check system behavior under extreme conditions.
- Example: Running thousands of concurrent requests to test system limits.
Example Use Case:
- In cloud-based applications, engineers may inject random server failures (e.g., shutting down instances) to ensure the system can recover without downtime.
- Netflix uses Chaos Monkey (a fault injection tool) to randomly terminate cloud instances and test system resilience.