docs: transform info

Author: Krzysztof Borowy

docs/Jest-integration.md

@@ -1,12 +1,12 @@
 # Jest integration
 
-Async Storage module is tighly coupled with a `Native Module`, meaning it needs a running React Native application to work properly. In order to use it in tests, you have to provide its separate implementation. Follow those steps to add mocked `Async Storage` to your test cases.
+Async Storage module is tighly coupled with its `NativeModule` part - it needs a running React Native application to work properly. In order to use it in tests, you have to provide its separate implementation. Follow those steps to add a mocked `Async Storage` module.
 
 ## Using Async Storage mock
 
-Select a method that suits your needs:
+You can use one of two ways to provide mocked version of `AsyncStorage`:
 
-### Mock `node_modules`
+### With __mocks__ directory
 
 1. In your project root directory, create `__mocks__/@react-native-community` directory.
 2. Inside that folder, create `async-storage.js` file.
@@ -16,62 +16,72 @@ Select a method that suits your needs:
 export default from '@react-native-community/async-storage/jest/async-storage-mock'
 ```
 
-### Use Jest setup files
+### With Jest setup file
 
 1. In your Jest config (probably in `package.json`) add setup files location:
 
 ```json
-  "jest": {
-    "setupFiles": ["./path/to/jestSetupFile.js"]
-  }
+"jest": {
+  "setupFiles": ["./path/to/jestSetupFile.js"]
+}
 ```
 
 2. Inside your setup file, set up Async Storage mocking:
 
 ```javascript
-  import mockAsyncStorage from '@react-native-community/async-storage/jest/async-storage-mock';
+import mockAsyncStorage from '@react-native-community/async-storage/jest/async-storage-mock';
 
-  jest.mock('@react-native-community/async-storage', () => mockAsyncStorage);
+jest.mock('@react-native-community/async-storage', () => mockAsyncStorage);
 ```
 ## Testing with mock
 
-Each public method available from `Async Storage` is [a mock function](https://jestjs.io/docs/en/mock-functions), that you can test for certain condition, for example, check if it has been called with a specific arguments:
+Each public method available from `Async Storage` is [a mock function](https://jestjs.io/docs/en/mock-functions), that you can test for certain condition, for example, if `.getItem` has been called with a specific arguments:
 
 ```javascript
-  it('checks if Async Storage is used', async () => {
-    await asyncOperationOnAsyncStorage();
+it('checks if Async Storage is used', async () => {
+  await asyncOperationOnAsyncStorage();
 
-    expect(AsyncStorage.getItem).toBeCalledWith('myKey');
-  })
+  expect(AsyncStorage.getItem).toBeCalledWith('myKey');
+})
 ```
 
 ## Overriding Mock logic
 
-You can override Async Storage mock implementation, by replacing its inner functions:
+You can override mock implementation, by replacing its inner functions:
 
 ```javascript
 // somewhere in your configuration files
 import AsyncStorageMock from '@react-native-community/async-storage/jest/async-storage-mock';
 
 AsyncStorageMock.multiGet = jest.fn(([keys], callback) => {
-  // do something here to retrieve files
+  // do something here to retrieve data
   callback([]);
 })
 
 export default AsyncStorageMock;
 ```
 
-You can [check mock implementation](../jest/async-storage-mock.js) to get more insight into its signatures.
+You can [check its implementation](../jest/async-storage-mock.js) to get more insight into methods signatures.
 
 ## Troubleshooting
 
 ### **`SyntaxError: Unexpected token export` in async-storage/lib/index.js**
 
-This is likely because `Jest` is not transforming Async Storage. You can point it to do so, by adding `transformIgnorePatterns` setting in Jest's configuration.
+**Note:** In React Native 0.60+, all `@react-native-community` packages are transformed by default.
+
+You need to point Jest to transform this package. You can do so, by adding Async Storage path to `transformIgnorePatterns` setting in Jest's configuration.
 
 
 ```json
 "jest": {
-    "transformIgnorePatterns": ["/node_modules/@react-native-community/async-storage/(?!(lib))"]
-  }
+  "transformIgnorePatterns": ["node_modules/(?!(@react-native-community/async-storage/lib))"]
+}
 ```
+
+Optionally, you can transform whole scope for `react-native-community` and `react-native`:
+
+```json
+"jest": {
+  "transformIgnorePatterns": ["node_modules/(?!(@react-native-community|react-native))"]
+}
+```