Add bare minimum documentation (#34)

* Add bare minimum documentation

* Add link to enzyme-to-json and remove reference to mount from enzyme

README.md

@@ -5,12 +5,73 @@
 
 ## Installation
 
+
 ```
 yarn add --dev jest-styled-components
 ```
 
+To render React components for testing you can use either `react-test-renderer` or `enzyme`.
+
+**Using react-test-renderer**
+
+
+Installation:
+
+```
+yarn add --dev react-test-renderer
+```
+
+Usage:
+
+```js
+import renderer from 'react-test-renderer'
+
+// somewhere in your tests
+test('matches the styled components snapshot', () => {
+  const tree = renderer.create(<MyComponent />).toJSON()
+  expect(tree).toMatchStyledComponentsSnapshot()
+  expect(tree).toHaveStyleRule('display', 'block')
+})
+```
+
+
+
+**Using enzyme and enzyme-to-json**
+
+Installation:
+
+```
+yarn add --dev enzyme enzyme-to-json
+```
+
+Usage:
+
+
+```js
+import {mount} from 'enzyme'
+import toJSON from 'enzyme-to-json'
+
+// inside your test
+test('can use enzyme instead of react-test-renderer', () => {
+  const wrapper = mount(<MyComponent />)
+  const tree = toJSON(wrapper)
+
+  const selector = '.btn-primary'
+  const subject = wrapper.find(selector)
+  expect(subject).toHaveStyleRule('color', 'whitesmoke')
+  expect(tree).toMatchStyledComponentsSnapshot()
+})
+```
+
+`enzyme-to-json` is only needed for snapshot testing, to learn more about snapshot testing with enzyme, go [here](https://www.npmjs.com/package/enzyme-to-json)
+
+
 ## toMatchStyledComponentsSnapshot [React]
 
+Learn more about Snapshot Testing with Jest [here](https://facebook.github.io/jest/docs/snapshot-testing.html), this matcher
+is used to assert complex selectors or to test your entire component in one go.
+
+
 ### Preview
 
 <img alt="Preview" src="assets/toMatchStyledComponentsSnapshot.png" width="500px" height="500px" />
@@ -29,6 +90,10 @@ expect(tree).toMatchStyledComponentsSnapshot()
 
 ## toHaveStyleRule [React]
 
+Only checks for the styles directly applied to the component it receives, to assert that a complex selector has been applied to
+a component, use `toMatchStyledComponentsSnapshot` instead.
+
+
 ### Preview
 
 <img alt="Preview" src="assets/toHaveStyleRule.png" width="470px" height="85px" />
@@ -47,6 +112,7 @@ expect(tree).toHaveStyleRule('property', value)
 
 ## toHaveStyleRule [React Native]
 
+
 ### Preview
 
 <img alt="Preview" src="assets/toHaveStyleRule1.png" width="440px" height="140px" />
@@ -64,3 +130,4 @@ import 'jest-styled-components/native'
 
 expect(tree).toHaveStyleRule('property', value)
 ```
+