Testing workshop

With professor Ronen Amiel

Agenda

• Talk about tests and why we write them.
• Live code a simple tic-tac-toe game.
• You clone the repo and continue to work on the game.
• From 16:00-19:00 we start the final exam and list homework for tomorrow morning (chapters 2-5).

You should write tests if you value your time

• Changing the code base doesn't require manually verifying that everything still works.

• Deploying new versions requires little or no manual testing.

• Reviewing others' code isn't about finding bugs but about design and quality.

You'll have more confidence over your code

• You'll have confidence your code still works after someone changed it. This also includes refactoring.
• Rollbacks happen a lot less often. When they do, you add a test that covers the cause for the rollback so it doesn't happen again.
• New team members can rest assured that their changes did not break any existing behavior.

Why TDD?

• Know that every line and edge case are covered by a test (well, mostly).
• Tests are good only when you trust them: TDD helps you write tests you trust.
• Instead of manually re-creating a use-case (normally, on the browser) use a as a way of re-creating the use-case.

When TDD?

• Helpful for making sure you didn't add new code that is not covered by a test.
• Great for covering edge cases: Found a bug? A use-case you didn't think about? Add a failing test and make it pass.
• Not right for everything: It's not necessarily the right tool for the job if you're prototyping, creating a POC, or working on a research task. Use common sense.

Types of Tests

Integration tests

Test the interaction from the end user's point of view. In our case, we will use Puppeteer to control a browser and interact with our app.

Unit tests

Test specific modules in isolation. Great for covering a lot of different permutations that can take longer with integration tests.

Unit tests: "Looks like it's working"

Component tests

Test a specific component in an environment that emulates a real browser (JSDOM). Great for testing different permutations in a component.

Write tests. Not too many. Mostly integration.

Guillermo Rauch - https://twitter.com/rauchg/status/807626710350839808

Tools

• Puppeteer: A Node.js library that provides an API for controlling a browser.
• JSDOM: JavaScript implementation of many browser APIs that emulate a browser environment in a Node.js process.
• Jest: JavaScript testing framework.
• Yoshi: A zero-configuration build tool for developing apps in Wix.

Puppeteer

A Node.js library that provides an API for controlling a browser.

JSDOM

JavaScript implementation of many browser APIs that emulate a browser environment in a Node.js process.

Jest

JavaScript testing framework.

Yoshi

A zero-configuration build tool for developing apps in Wix.

Let's code :)