Various browsers and devices have their own specifications and standards for the kinds of favicon-like icons they use to represent web pages. This answer on the graphic design site gives a pretty good overview.
Suppose you've gone to the trouble to provide a good number of these icon files with the appropriate declarations in your HTML - but you don't happen to have every device Apple has produced plus a Windows 8 device plus various versions of Android to hand to test them all.
Is there any straightforward way to test your configuration and see what files (if any) various devices and browsers will have, without having all the necessary devices to hand?
I would suggest trying out device emulation in Google Chrome. It is the easiest way I have seen and it should work. Here is a full article on it, https://developer.chrome.com/devtools/docs/device-mode
I've always used the favicon generator at realfavicongenerator.net, which allows you to see how your chosen artwork will appear on different devices. There are quite a few options and you can try with their example icon to test. Start with a square SVG for the best results as the site will convert it to the necessary formats and give you a compressed folder with everything ready to use.
It's also a free service with no registration or other nonsense required. Just use it and donate if you find it useful.
Just test these by using Mozilla Firefox , most of the web applications developers are using this method for testing