What is System Testing?

System Testing is a type of software testing where the entire software application is tested as a whole to verify that it meets the specified requirements. It is conducted after Integration Testing and before User Acceptance Testing (UAT).

Key Objectives of System Testing

✅ Ensures that the complete system meets business and functional requirements.
✅ Identifies bugs and inconsistencies across modules.
✅ Evaluates performance, security, and usability.
✅ Tests system behavior under real-world conditions.

Performed by: Independent Testers (QA Team)
Automation Tools: Selenium, TestNG, JUnit, QTP, LoadRunner, JMeter
Testing Phase in SDLC: After Integration Testing, Before UAT

Types of System Testing

System Testing is divided into Functional and Non-Functional testing types.

1️⃣ Functional System Testing (Validates Features & Business Logic)

Functional testing ensures that the system works correctly as per requirements.

1. Smoke Testing

A quick test to check if major system functionalities are working.
Performed before deeper testing to ensure system stability.
📌 Example: Checking if a login page loads properly before testing other features.

2. Sanity Testing

Focuses on verifying specific bug fixes or new features.
📌 Example: If a checkout issue was fixed, sanity testing checks only that functionality.

3. Regression Testing

Ensures new changes do not break existing functionality.
📌 Example: After adding a new payment method, regression testing verifies that all previous payment methods still work.

4. End-to-End Testing

Tests complete workflows from start to finish.
📌 Example: Testing an e-commerce website from login → product search → checkout → payment → order confirmation.

5. User Interface (UI) Testing

Ensures the system’s graphical interface is working correctly.
📌 Example: Checking if buttons, fonts, colors, and navigation in a mobile app appear correctly.

6. Database Testing

Ensures data storage, retrieval, and integrity are correct.
📌 Example: Testing if a banking application saves user transactions correctly.

7. API Testing

Verifies if APIs are returning correct responses and data.
📌 Example: A weather API should return correct temperature data for a given city.

2️⃣ Non-Functional System Testing (Checks Performance, Security & Usability)

Non-functional testing evaluates performance, security, and reliability of the system.

8. Performance Testing

Checks speed and response time of the system.
📌 Example: An online store should load in under 2 seconds even with multiple users.

9. Load Testing

Ensures the system handles expected traffic loads.
📌 Example: Testing if a ticket booking site supports 10,000 concurrent users.

10. Stress Testing

Pushes the system beyond normal limits to find failure points.
📌 Example: Simulating 1 million users on a cloud app to check when it crashes.

11. Scalability Testing

Evaluates if the system can scale up with increasing load.
📌 Example: Ensuring a video streaming service scales from 100 users to 100,000 users.

12. Endurance (Soak) Testing

Runs the system for a long period to check for memory leaks or performance degradation.
📌 Example: Running a banking system for 24 hours non-stop to check stability.

13. Security Testing

Identifies vulnerabilities, risks, and security flaws.
📌 Example: Checking if a banking app encrypts passwords correctly.

14. Penetration Testing

Simulates cyber-attacks to check system security.
📌 Example: Ethical hackers try to break into an e-commerce site.

15. Compliance Testing

Ensures the software follows legal and regulatory standards.
📌 Example: A healthcare app must comply with HIPAA regulations.

16. Usability Testing

Ensures the software is user-friendly and intuitive.
📌 Example: Testing if a travel booking website is easy to use.

17. Accessibility Testing

Ensures the software is usable by people with disabilities.
📌 Example: Checking if a government website supports screen readers.

18. Installation & Uninstallation Testing

Ensures the software installs, updates, and uninstalls correctly.
📌 Example: Checking if a mobile banking app installs properly on Android & iOS.

19. Recovery Testing

Tests how well the system recovers from failures.
📌 Example: If an e-commerce website crashes, it should restart within seconds.

Comparison of System Testing Types

Testing Type	Purpose	Example
Smoke Testing	Quick system check	Checking if login & homepage load
Regression Testing	Ensures updates don’t break existing features	Testing old & new payment options
Performance Testing	Measures system speed	Checking response time of a website
Load Testing	Simulates expected traffic	Can the app handle 10,000 users?
Security Testing	Checks for vulnerabilities	Is user data encrypted properly?
Usability Testing	Ensures good UX	Can users easily book a flight?
Database Testing	Ensures data integrity	Are transactions stored correctly?