Full Stack Web Development Full Stack Integration & Project Engineering Flashcards

24 sample cards from the Full Stack Integration & Project Engineering deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What does multipart/form-data encoding allow that application/x-www-form-urlencoded does not?

   It allows binary file uploads alongside form fields by splitting the body into parts, making it the required encoding for sending files in an HTML form.

2. What is a common cloud service used to store uploaded media instead of the local server disk?

   Amazon S3 (or Cloudinary), which offloads storage, provides scalability/CDN delivery, and keeps files off the application server.

3. What is the typical flow for integrating a payment gateway like Stripe or Razorpay?

   Frontend collects payment details/creates an order -> backend creates a payment intent/order with the gateway using secret keys -> gateway processes the payment -> a webhook or callback confirms success -> backend updates the order status.

4. Why should third-party API secret keys never be exposed in front-end code?

   Front-end code is fully visible to users, so embedded secret keys could be stolen and abused; secrets must stay on the server (e.g., in environment variables) and only publishable keys go to the client.

5. What is a webhook in the context of third-party APIs?

   An HTTP callback the third-party service sends to a URL you register, notifying your backend of events (e.g., payment succeeded) so your app can react without polling.

6. What is the main purpose of automated software testing?

   To verify that code behaves as expected, catch regressions early, document intended behavior, and increase confidence when refactoring or shipping changes.

7. Define the three classic levels of the testing pyramid.

   Unit tests (smallest, isolated functions/components), integration tests (multiple units working together), and end-to-end (E2E) tests (the full app from the user's perspective). The pyramid recommends many unit, fewer integration, fewest E2E.

8. What is the difference between a unit test and an integration test?

   A unit test verifies a single isolated piece of code with dependencies mocked; an integration test verifies that several components/modules work correctly together, including real interactions.

9. What does TDD (Test-Driven Development) prescribe?

   The Red-Green-Refactor cycle: write a failing test first (Red), write minimal code to pass it (Green), then refactor while keeping tests passing.

10. What is a mock (or stub) in testing?

    A fake replacement for a real dependency that simulates its behavior, letting you test code in isolation and control inputs/outputs without invoking the real service.

11. What is the role of an assertion in a test?

    An assertion checks that an actual value matches the expected value (e.g., expect(result).toBe(5)); if it fails, the test fails.

12. Which two libraries are most commonly used together to test React components?

    Jest (test runner/assertions/mocking) and React Testing Library (RTL) for rendering components and querying the DOM the way a user would.

13. What testing philosophy does React Testing Library promote?

    Testing behavior the way users interact with the app (querying by visible text, roles, labels) rather than testing implementation details like internal state or class names.

14. How do you simulate user interaction events in React Testing Library?

    Using fireEvent or, preferably, the user-event library (e.g., userEvent.click, userEvent.type) to mimic real user actions.

15. What is snapshot testing?

    A test that renders a component and saves a serialized snapshot of its output; future runs compare against the saved snapshot and fail if the output changes unexpectedly.

16. Which library is widely used for back-end/API testing of Express HTTP endpoints?

    Supertest (often with Jest or Mocha), which sends HTTP requests to the Express app and lets you assert on status codes and response bodies.

17. When API testing, what should you typically assert about a response?

    The HTTP status code, the response body content/shape, response headers when relevant, and side effects such as database state changes.

18. Why is a separate test database (or in-memory database) recommended for API/integration tests?

    To isolate tests from production/development data, ensure repeatable clean state, and avoid corrupting real data; MongoDB Memory Server is often used for this.

19. What is end-to-end (E2E) testing?

    Testing that runs the complete application (frontend, backend, database) and simulates real user workflows in a browser to verify the whole system works together.

20. Name two popular E2E testing tools for web apps.

    Cypress and Playwright (Selenium is another classic option).

21. What does code coverage measure, and what is a key caveat about it?

    It measures the percentage of code executed by tests (lines, branches, functions). The caveat: high coverage does not guarantee correctness, since executed code may still lack meaningful assertions.

22. What does the MVC pattern stand for and what does each part do?

    Model-View-Controller. Model handles data/business logic, View handles presentation, Controller handles input and coordinates between Model and View.

23. What is separation of concerns in code architecture, and why does it matter?

    Dividing an application into distinct sections each handling one responsibility (e.g., routes, controllers, services, models). It improves maintainability, testability, and reusability.

24. Name three core practices for securing a full-stack web application before deployment.

    Use HTTPS/TLS, validate and sanitize all user input (preventing XSS/SQL/NoSQL injection), and store secrets/passwords securely (env variables, hashing). Also: set security headers (e.g., via Helmet), enforce auth/authorization, and rate-limit requests.

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