When you're writing tests, you often need to check that values meet certain conditions. expect gives you access to a number of "matchers" that let you validate different things.| jestjs.io
In your test files, Jest puts each of these methods and objects into the global environment. You don't have to require or import anything to use them. However, if you prefer explicit imports, you can do import {describe, expect, test} from '@jest/globals'.| jestjs.io
Often while writing tests you have some setup work that needs to happen before tests run, and you have some finishing work that needs to happen after tests run. Jest provides helper functions to handle this.| jestjs.io