Microsoft Edge was a good idea overall. A new (and better) rendering engine, and a new name to replace the tired “Internet Explorer” brand. While adoption is slow, it is likely to pick up in the next years, so it’s something that web designers and developers can’t afford to ignore.
The thing here is the new (and better) rendering engine. It has no continuity with the old IE. If you test a site on IE and it works, there is no guarantee it will work the same on Edge. And that causes a difficulty for developers who, due to personal or company-dictated reasons have to stick with an older version of Windows (7, 8, or 8.1) for now. As most of us know, these people cannot run Edge. It requires Windows 10, period.
Of course, we’ve had a similar problem with Safari for a long time — you can only run it on a Mac, unless you want to do a lot of hacking and violate Apple’s EULA. However, Safari is rather predictable and stable these days, and I am confident enough to release stuff that I have not specifically tested on Safari. Google Chrome’s rendering engine is directly related to Safari’s, so testing on Chrome is usually good enough for me.
Well, it turns out that Microsoft, as it often does, has decided to be nice to developers and provide free and reliable testing tools. They have published a developer resources site with many tools — completely free of charge. You can either download a virtual machine to run your preferred browser, directly obtain screenshots of your website, or use the RemoteIE service to launch a remote version of IE11 running the EdgeHTML rendering engine. I chose the last option and was able to detect and fix all the glitches that I mentioned above.