Toggle is a term used to describe a switch or button that enables users to change the current state of a feature. In many cases this is done to test features that have not yet been fully developed or deployed for a broad user base. This also enables teams to roll out updates without affecting existing users.
A toggle can be a simple checkbox or radio button, but in other cases it may be more complex. The toggle can be positioned vertically if the layout requires it, or horizontally if that is preferred. A loading indicator can be displayed if the toggle is waiting for something to load before it can change states.
The toggle is usually rendered in the same color as its label, although there is some flexibility. This is a best practice to prevent confusion, but a research study showed that if the toggle was colored differently from its label, this could lead to an increased error rate.
Toggles are a great tool to help your team develop software faster, and can be an alternative to traditional code branches for new functionality. They allow your team to perform a complete development and testing process on trunk code, without having to wait for that functionality to be ready to be merged into the main release.
When you are using feature toggles, it is important to test all the configurations of those toggles which you expect to be live in production. This includes those toggles which you are expecting to be flipped Off as well as those you are planning to release with flipped On. Many teams also include tests of the fallback configuration (which is the toggles which you are expecting to be rolled back to).
