見つけた不具合をFirefoxにフィードバックする時には、それが後退バグである場合、いつの時点から不具合が発生するようになったのかという情報を書き添えておく事が大事です。この記事では、Firefoxの後退バグの発生時期を割り出す事を支援するツールであるmozregressionの使い方を解説します。 後退バグとは？ 後退バグ（regression）とは、今まで正常に動いていた機能が、別の箇所の変更の影響を受けて、意図せず壊れてしまった、というケースを言い表す言葉です。 規模の大きなソフトウェアや複雑なソフトウェアでは、気をつけていても後退バグがどうしても発生してしまいがちです。後退バグが発生した直後にすぐに気付ければいいのですが、普段あまり使わない機能だと、いつからかは分からないが気がついたらその機能がずっと壊れたままだった、という事も起こりえます。 このような場面でよく使われるのが、二分

If you know the ropes, good news! Firefox now has support for headless mode, making it easier to use as a backend to automated tools. You can jump ahead to learn how to use it. Browser automation is not a new idea, but is an increasingly important part of how modern websites are built, tested, and deployed. Automation setups range from scripts run on local machines to vast deployments of specializ

Comparing Browser Page Load Time: An Introduction to Methodology On blog.mozilla.org, we shared results of a speed comparison study to show how fast Firefox Quantum with Tracking Protection enabled is compared to other browsers. While the blog post there focuses on the results and the speed benefits that Tracking Protection can deliver to users even outside of Private Browsing, we also wanted to s

As of version 56 (currently in Beta), Firefox supports running headlessly on Windows, macOS, and Linux. Brendan Dahl has previously described how to use SlimerJS to drive headless Firefox. You can also drive it via the W3C WebDriver API, and this blog post explains how to do that in Node.js with the selenium-webdriver package. (For a similar introduction using Python on Windows, see Andre Perunici

The bad news: from Firefox 55 onwards, Selenium IDE will no longer work. The reasons for this are complex, but boil down to two main causes: Browsers are complicated pieces of software that are constantly evolving. Mozilla has been working hard to make Firefox faster and more stable, while still retaining the flexibility and ease of extension that we’ve come to know and love. As part of that proce

For bugs in Firefox Desktop, the Mozilla Foundation's web browser. For Firefox user interface issues in menus, bookmarks, location bar, and preferences. Many Firefox bugs will either be filed here or in the Core product. Bugs for developer tools (F12) should be filed in the DevTools product. (more info)

For bugs in Firefox Desktop, the Mozilla Foundation's web browser. For Firefox user interface issues in menus, bookmarks, location bar, and preferences. Many Firefox bugs will either be filed here or in the Core product. Bugs for developer tools (F12) should be filed in the DevTools product. (more info)

WebAssembly is a new, cross-browser format for programs on the Web. You can read all about it in Lin Clark‘s six-part series, A cartoon intro to WebAssembly. Unlike JavaScript, WebAssembly is a binary format, which means developers need new tools to help understand and experiment with WebAssembly. One such tool is Mozilla’s WebAssembly Explorer. The video below demonstrates the basic functions of

Interacting with insecure SSL pages (eg. self-signed) in an automated test written for Selenium is an important feature. Especially when tests are getting run against locally served test pages. Under those circumstances you might never get fully secured websites served to the browser instance under test. To still allow running your tests with a successful test result, Selenium can instruct the bro