fix links (#2257)

content/docs/testing.md

@@ -28,7 +28,7 @@ Different answers may work for different teams and products.
 
 ### Recommended Tools {#tools}
 
-**[Jest](https://facebook.github.io/jest/)** is a JavaScript test runner that lets you access the DOM via [`jsdom`](#mocking-a-rendering-surface). While jsdom is only an approximation of how the browser works, it is often good enough for testing React components. Jest provides a great iteration speed combined with powerful features like mocking [modules](#mocking-modules) and [timers](#mocking-timers) so you can have more control over how the code executes.
+**[Jest](https://facebook.github.io/jest/)** is a JavaScript test runner that lets you access the DOM via [`jsdom`](/docs/testing-environments.html#mocking-a-rendering-surface). While jsdom is only an approximation of how the browser works, it is often good enough for testing React components. Jest provides a great iteration speed combined with powerful features like mocking [modules](/docs/testing-environments.html#mocking-modules) and [timers](/docs/testing-environments.html#mocking-timers) so you can have more control over how the code executes.
 
 **[React Testing Library](https://testing-library.com/react)** is a set of helpers that let you test React components without relying on their implementation details. This approach makes refactoring a breeze and also nudges you towards best practices for accessibility. Although it doesn't provide a way to "shallowly" render a component without its children, a test runner like Jest lets you do this by [mocking](/docs/testing-recipes.html#mocking-modules).