Add Usage in Jest to pretty-format/README.md

packages/pretty-format/README.md

@@ -145,6 +145,31 @@ const formatted2 = prettyFormat(renderer.create(element).toJSON(), {
 */
 ```
 
+## Usage in Jest
+
+For snapshot tests, Jest uses `pretty-format` with options that include some of its built-in plugins. For this purpose, plugins are also known as **snapshot serializers**.
+
+To serialize application-specific data types, you can add modules to `devDependencies` of a project, and then:
+
+In an **individual** test file, you can add a module as follows. It precedes any modules from Jest configuration.
+
+```js
+import serializer from 'my-serializer-module';
+expect.addSnapshotSerializer(serializer);
+
+// tests which have `expect(value).toMatchSnapshot()` assertions
+```
+
+For **all** test files, you can specify modules in Jest configuration. They precede built-in plugins for React, HTML, and Immutable.js data types. For example, in a `package.json` file:
+
+```json
+{
+  "jest": {
+    "snapshotSerializers": ["my-serializer-module"]
+  }
+}
+```
+
 ### Plugins
 
 Pretty format also supports adding plugins: