What types of testing do you know?

• Unit Testing: Testing individual, smallest parts of code (modules, classes, methods) in isolation. The goal is to ensure that each component works correctly on its own. Frameworks like JUnit, Mockito are used.

• Integration Testing: Testing the interaction between different modules or systems. The goal is to ensure that components work correctly together. It may include testing interactions with databases, APIs, third-party services.

• Functional Testing: Verifying that the system meets functional specifications and requirements. Testing is conducted from the user's perspective, checking that the system does what it is supposed to do.

• System Testing: Testing a fully integrated system to evaluate its compliance with specified requirements. Includes testing performance, security, reliability, and other non-functional aspects.

• Acceptance Testing: Formal testing conducted to determine whether the system meets acceptance criteria and is ready for deployment. It may be conducted by the customer or end-users.

• Regression Testing: Re-running previously completed tests after making changes to the code (bug fixes, new features) to ensure that the changes have not broken existing functionality.

• Performance Testing: Assessing system performance under a certain workload. Includes:

  • Load Testing: Checking system behavior under expected load.
  • Stress Testing: Checking system behavior under exceeding expected load to determine failure points.
  • Scalability Testing: Evaluating the system's ability to handle increased load.

• Security Testing: Assessing system vulnerabilities to attacks. Includes:

  • Penetration Testing: Simulating real attacks to find weaknesses.
  • Vulnerability Scanning: Using tools to automatically detect known vulnerabilities.

• Usability Testing: Evaluating the ease and intuitiveness of the user interface.

• API Testing: Testing application programming interfaces (APIs) for functionality, reliability, and performance.

A brief comparison of some types:

Test Type	Focus	Who Usually Performs
Unit	Individual modules	Developers
Integration	Interaction of modules	Developers, QA
Functional	Compliance with requirements	QA
Acceptance	Readiness for deployment	Customer, QA

// Example of a simple unit test using JUnit
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;

public class CalculatorTest {

    @Test
    void testAddition() {
        Calculator calculator = new Calculator();
        int result = calculator.add(2, 3);
        assertEquals(5, result, "2 + 3 should be 5");
    }

    // Presumed Calculator class (for example)
    static class Calculator {
        public int add(int a, int b) {
            return a + b;
        }
    }
}