Software Testing and JUnit and Best Practices

Software Testing
Tung Thanh Nguyen, PhD
Department of Computer Science
Fulbright University Vietnam

Introduction to Software Testing
• Software testing ensures software quality
• Detecting bugs and verifying functionality.
• Validating that software meets requirements and behaves as expected.
• JUnit is a popular testing framework for Java applications.

Types of Software Testing
• Manual Testing - Performed by humans without automation.
• Automated Testing - Uses software tools to run tests automatically.
• Unit Testing - Tests individual components of code.
• Integration Testing - Verifies interactions between components.
• System Testing - Tests all system’s functionality.
• User Acceptance Testing - Validates software requirements from user
perspective.

Junit – Testing framrwork for Java
• Provides a structured way to write and execute tests.
• Supports test automation.
• Integrates well with build tools (e.g., Maven, Gradle).
• Helps ensure code reliability and maintainability.

Installing JUnit
• Add JUnit dependency to Maven:
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>5.7.1</version>
<scope>test</scope>
</dependency>

Writing a Basic JUnit Test
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;
class CalculatorTest {
@Test
void testAddition() {
assertEquals(5, 2 + 3);
}
}

JUnit Annotations
• @Test - Marks a test method.
• @BeforeEach - Runs before each test.
• @AfterEach - Runs after each test.
• @BeforeAll - Runs once before all tests.
• @AfterAll - Runs once after all tests.

Setup and Teardown Methods
import org.junit.jupiter.api.*;
class TestLifecycle {
@BeforeEach
void setUp() {
System.out.println("Setting up test");
}
@AfterEach
void tearDown() {
System.out.println("Cleaning up test");
}
@Test
void exampleTest() {
assertTrue(true);
}
}

Testing Exceptions
class ExceptionTest {
@Test
void testException() {
assertThrows(ArithmeticException.class, () -> {
int result = 10 / 0;
});
}
}

Parameterized Tests
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
class ParameterizedExample {
@ParameterizedTest
@ValueSource(ints = {1, 2, 3})
void testNumbers(int number) {
assertTrue(number > 0);
}
}

Test Coverage Metrics
• Statement Coverage - Tests if each line is executed.
• Branch Coverage - Ensures all branches in control structures execute.
• Path Coverage - Tests all possible paths in a function.

Assertions in JUnit
class AssertionsExample {
@Test
void testAssertions() {
assertEquals(4, 2 + 2);
assertNotNull("Hello");
assertTrue(5 > 3);
}
}

Running JUnit Tests
• Use mvn test for Maven projects.
• Use gradle test for Gradle projects.
• Run tests directly in IDE (e.g., IntelliJ, Eclipse).

Continuous Integration with JUnit
• Use Jenkins, GitHub Actions, or GitLab CI/CD.
• Automate test execution on code commits.

Handling Test Failures
• Check error messages and stack traces.
• Debug using breakpoints.
• Improve test reliability with proper setup.

Best Practices in Unit Testing
• Keep tests independent.
• Use meaningful test names.
• Cover edge cases.
• Run tests frequently.

Summary
• Software testing is crucial for code quality.
• JUnit simplifies unit testing.
• Use assertions and CI/CD for robust testing.

Software Testing and JUnit and Best Practices

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