# "Introduction to WPT" video transcript
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**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.
> We're looking forward to working with you!