Success Criterion 2.5.1: 2.5.1 Pointer Gestures (Level A): All functionality that uses multipoint or path-based gestures for operation can be operated with a single pointer without a path-based gesture, unless a multipoint or path-based gesture is essential.
With increase in touch devices, method of pointer gestures have become quite common. It has also become popular when users can use diverse range of gestures.
Let’s take an example of a news app; by use of pinch, user can zoom in and zoom out the text. However, when user does not have ability to pinch, there should be alternate method of achieving the same functionality. Perhaps by using Zoom-in and Zoom-out buttons or with an option in app settings.
That said, this success criterion does not to apply to functionality provided for the operating systems – such as swiping down to bring notification menu or functionality provided in assistive technologies; such as talk back (screen reader on Android) has its own gestures for ease of use.
Another exception is where path based gesture is a mandatory such as drawing a signature.
How to test?
Identify if a functionality requires use of path based gesture such as swiping, dragging or drawing. One of the examples would be “Place an order” element on Amazon app where user requires to swipe from left to right to complete the order. Another example would be zoom-in or zoom-out on maps.