# "Introduction to WPT" video transcript **Still image of the WPT logo. The song ["My Luck"](http://brokeforfree.bandcamp.com/track/my-luck) by [Broke for Free](http://brokeforfree.com/) (licensed under [Creative Commons Attribution 3.0](https://creativecommons.org/licenses/by/3.0/)) plays in the background.** > Hello, and welcome to the Web Platform Tests! > > The goal of this project is to ensure that all web browsers present websites > in exactly the way the authors intended. > > But what is the web platform, exactly? You can think of it as having three > main parts. **A top-down shot of a blank sheet of graph paper** > First, there are the web browsers. A hand places a paper cutout depicting a browser window in the lower-right corner of the sheet. > Applications like Firefox, Chrome, and Safari allow people to interact with > pages and with each other. > > Second, there are the web standards. A hand places a paper cutout depicting a scroll of parchment paper in the lower-left corner of the sheet. > These documents define how the browsers are supposed to behave. **A screen recording of a web browser** `https://platform.html5.org` is entered into the location bar, and the browser loads the page. > That includes everything from how text is rendered to how augmented reality > apps are built. Specifying it all takes a lot of work! The browser clicks through to the Fetch standard and begins scrolling. > And as you might expect, the standards can get really complicated. **Return to the graph paper** A hand draws an arrow from the cutout of the scroll to the cutout of the browser window. > The people who build the browsers use the specifications as a blue print for > their work. A shared set of generic instructions like these make it possible > for people to choose between different browsers, but only if the browsers get > it right. A hand places a cutout representing a stack of papers on the top-center of the sheet and draws an arrow from that cutout to the cutout of the browser window. > To verify their work, the browser maintainers rely on the third part of the > web platform: conformance tests. A hand draws an arrow from the cutout of the scroll to the cutout of the tests. > We author tests to describe the same behavior as the standards, just > formatted in a way that a computer can understand. A hand draws an arrow from the cutout of the browser window to the cutout of the scroll. > In the process, the maintainers sometimes uncover problems in the design of > the specifications, and they recommend changes to fix them. A hand draws an arrow from the cutout of the tests to the cutout of the scroll. > Test authors also find and fix these so-called "spec bugs." A hand draws an arrow from the cutout of the browser window to the cutout of the tests. > ...and as they implement the standards, the maintainers of each browser > frequently write new tests that can be shared with the others. > > This is how thousands of people coordinate to build the cohesive programming > platform that we call the world wide web. The web-platform-tests project is > one of the test suites that make this possible. > > That's pretty abstract, though! Let's take a quick look at the tests > themselves. **A screen recording of a web browser** `http://wpt.live` is entered into the location bar, and the browser loads the page. > The latest version of the tests is publicly hosted in executable form on the > web at wpt.live. The browser begins scrolling through the enormous list of directories. > There, were can navigate among all the tests for all the different web > technologies. > > Let's take a look at a typical test. The browser stops scrolling, and a mouse cursor clicks on `fetch`, then `api`, then `headers`, and finally `headers-basic.html`. > This test is written with the web-platform-tests's testing framework, > testharness.js. The test completes almost instantly, and testharness.js > reports that this browser passes all but one subtest. To understand the > failure, we can read the source code. The mouse opens a context menu, selects "View Source", and scrolls to the source of the failing test. > It looks like the failing subtest is for what happens when a `Headers` > instance has a custom JavaScript iterator method. That's a strange edge case, > but it's important for browsers to agree on every detail! The mouse clicks on the browser's "Back" button and then navigates through the directory structure to the test at `css/css-transforms/transform-transformed-tr-contains-fixed-position.html`. It displays text rendered at an angle. > Many tests don't use testharness.js at all. Let's take a look at a couple > other test types. > > When it comes to the visual appearance of a page, it can be hard to verify > the intended behavior using JavaScript alone. For these situations, the > web-platform-tests uses what's known as a reftest. > > Short for "reference test", this type of test uses at least two different web > pages. > > The first page demonstrates the feature under test. The mouse opens a context menu, selects "View Source", and clicks on the `href` value for the matching reference. It looks identical to the previous page. > Inside of it, we'll find a link to a second page. This second page is the > reference page. It's designed to use a different approach to produce the same > output. The mouse clicks back and forth between the browser tabs displaying the test page and the reference page. > When tests like these are run automatically, a computer verifies that > screenshots of the two pages are identical. The mouse clicks on the browser's "Back" button and then navigates through the directory structure to the test at `css/css-animations/animation-fill-mode-002-manual.html`. The page includes the text, "Test passes if there is a filled color square with 'Filler Text', whose color gradually changes in the order: YELLOW to GREEN." It also includes the described animated square. > Even with testharness.js and reftests, there are many web platform features > that a computer can't automatically verify. In cases like these, we fall back > to using manual tests. > > Manual tests can only be verified by a living, breathing human. They describe > their expectations in plain English so that a human operator can easily > determine whether the browser is behaving correctly. `https://web-platform-tests.org` is entered into the location bar, and the browser loads the page. > You can read more about all the test types in the project documentation at > [web-platform-tests.org](https://web-platform-tests.org). `https://wpt.fyi` is entered into the location bar, and the browser loads the page. > [wpt.fyi](https://wpt.fyi) is a great way to see how today's browsers are > performing on the web-platform-tests. The browser scrolls to `fetch`, and a mouse cursor clicks on `fetch`, then `api`, then `headers`, and finally `headers-basic.html`. > Here, you'll find all the same tests, just presented with the results from > various browsers. `https://web-platform-tests.live/LICENSE.md` is entered into the location bar, and the browser loads the page. > The web-platform-tests project is free and open source software. From bug > reports to documentation improvements and brand new tests, we welcome all > sorts of contributions from everyone. `https://github.com/web-platform-tests/wpt` is entered into the location bar, and the browser loads the page. > To get involved, you can visit the project management website hosted on > GitHub.com. The browser navigates to the project's "issues" list and filters the list for just the ones labeled as "good first issue." > Some issues are more difficult than others, but many are perfect for people who > are just getting started with the project. When we come across an issue like > that, we label it as a "good first issue." `https://lists.w3.org/Archives/Public/public-test-infra` is entered into the location bar, and the browser loads the page. > You can also join the mailing list to receive e-mail with announcements and > discussion about the project. `http://irc.w3.org/` is entered into the location bar, and the browser loads the page. `web4all` is entered as the Nickname, and `#testing` is entered as the channel name. A mouse clicks on the "Connect" button. > For more immediate communication, you can join the "testing" channel on the > IRC server run by the W3C. **Return to the graph paper** A hand places a paper cutout depicting a human silhouette on the sheet. It then draws arrows from the new cutout to each of the three previously-introduced cutouts. ![](assets/web-platform.png "The diagram drawn in the video") > We're looking forward to working with you!