What is Unit Testing?
Unit Testing focuses on verifying the smallest testable parts of an application, such as functions, methods, or classes. It helps detect issues early and improves code reliability.
Objectives of Unit Testing
- Validate individual components
- Detect bugs at an early stage
- Ensure correctness of code logic
Advantages
- Early defect detection
- Improves code quality and reliability
- Makes debugging easier
Limitations
- Cannot catch integration issues
- Requires writing multiple test cases
- Maintenance overhead for test scripts
Unit Testing Process
- Identify modules or functions to test
- Write test cases for each unit
- Execute tests using tools like JUnit or TestNG
- Analyze results and fix defects
- Re-run tests after code changes
Example
Example: Testing a function that calculates the sum of two numbers independently before using it in the main program.
Tools for Unit Testing
- JUnit (Java)
- TestNG (Java)
- NUnit (.NET)
- PyTest (Python)
Best Practices
- Write clear and independent test cases
- Automate tests for regression coverage
- Keep tests small and focused
- Use mocks and stubs to isolate units
