13-3 Testing and Debugging Explained

Key Concepts

• Unit Testing
• Integration Testing
• End-to-End Testing
• Debugging Techniques
• Error Handling
• Logging
• Test Coverage
• Mocking and Stubbing
• Continuous Integration
• Test Automation
• Performance Testing
• Security Testing
• Test-Driven Development (TDD)

1. Unit Testing

Unit testing involves testing individual components or units of code to ensure they function correctly in isolation.

Example:

        describe('Calculator', function() {
            it('should add two numbers', function() {
                expect(add(1, 2)).toBe(3);
            });
        });
    

Imagine unit testing as checking each part of a machine to ensure it works before assembling the entire machine.

2. Integration Testing

Integration testing involves testing how different units or components work together as a group.

Example:

        describe('UserService', function() {
            it('should fetch user data and display it', function() {
                var userService = new UserService();
                var userData = userService.getUserData();
                expect(userData.name).toBe('John Doe');
            });
        });
    

Consider integration testing as checking how different parts of a machine work together once assembled.

3. End-to-End Testing

End-to-End testing involves testing the entire application from start to finish to ensure it works as expected in a real-world scenario.

Example:

        describe('E2E Test', function() {
            it('should log in and view user profile', function() {
                browser.get('http://example.com/login');
                element(by.model('username')).sendKeys('user');
                element(by.model('password')).sendKeys('pass');
                element(by.id('loginButton')).click();
                expect(browser.getCurrentUrl()).toContain('/profile');
            });
        });
    

Think of End-to-End testing as using a product from start to finish to ensure it meets all functional requirements.

4. Debugging Techniques

Debugging involves identifying and fixing errors in the code. Techniques include using browser developer tools, console logs, and breakpoints.

Example:

        function add(a, b) {
            console.log('Adding', a, 'and', b);
            return a + b;
        }
    

Consider debugging as finding and fixing a leak in a pipe. You use tools (debugging techniques) to locate and repair the issue.

5. Error Handling

Error handling involves managing and responding to errors that occur during the execution of the application.

Example:

        try {
            var result = add(1, '2');
        } catch (error) {
            console.error('Error:', error.message);
        }
    

Think of error handling as having a safety net to catch and manage mistakes (errors) that occur during a performance.

6. Logging

Logging involves recording events and errors in the application to help with debugging and monitoring.

Example:

        app.run(function($log) {
            $log.info('Application started');
        });
    

Consider logging as keeping a diary of events. It records what happens (logs) during the day (application execution).

7. Test Coverage

Test coverage measures the percentage of code that is covered by tests. It helps identify untested parts of the codebase.

Example:

        // Using Istanbul to measure test coverage
    

Think of test coverage as a map that shows which areas of a city (codebase) have been explored (tested) and which are still uncharted.

8. Mocking and Stubbing

Mocking and stubbing involve creating fake versions of components or services to isolate the code being tested.

Example:

        var mockService = jasmine.createSpyObj('mockService', ['getData']);
        mockService.getData.and.returnValue('mockData');
    

Consider mocking and stubbing as using stand-ins in a movie. The stand-ins (mocks/stubs) replace the real actors (components/services) to ensure the focus remains on the main character (code being tested).

9. Continuous Integration

Continuous Integration (CI) involves integrating code changes frequently and running automated tests to catch issues early.

Example:

        // Configure CI in your project
    

Think of CI as a factory assembly line that continuously checks each product (code change) for defects before it moves to the next stage.

10. Test Automation

Test automation involves using tools to run tests automatically, reducing the need for manual testing.

Example:

        // Using Protractor for E2E test automation
    

Consider test automation as a robot that performs repetitive tasks (tests) to ensure consistency and accuracy.

11. Performance Testing

Performance testing involves evaluating the speed, responsiveness, and stability of the application under various conditions.

Example:

        // Using tools like Lighthouse for performance testing
    

Think of performance testing as tuning a car. Each adjustment (test) improves the performance (speed and efficiency) of the vehicle (application).

12. Security Testing

Security testing involves identifying vulnerabilities and ensuring the application is secure from attacks.

Example:

        // Using tools like OWASP ZAP for security testing
    

Consider security testing as installing a security system in your home. It deters burglars (attacks) and ensures safety.

13. Test-Driven Development (TDD)

Test-Driven Development (TDD) is a practice where tests are written before the code. It ensures that the code meets the requirements and functions correctly.

Example:

        // Write a test for a function that doesn't exist yet
        it('should return the sum of two numbers', function() {
            expect(add(1, 2)).toBe(3);
        });
    

Think of TDD as building a house. You first create a blueprint (test) before laying the foundation (writing code).