docs: add using with jest guide

Author: eddyerburgh

docs/en/SUMMARY.md

@@ -37,4 +37,7 @@
     * [setProps](api/wrapper-array/setProps.md)
     * [trigger](api/wrapper-array/trigger.md)
   * [selectors](api/selectors.md)
+  * guides
+    * [using with Jest](guides/using-with-jest.md)
+    * [testing compiled components with Jest](guides/using-compiled-components-with-jest.md)
   * [common gotchas](common-gotchas.md)

docs/en/guides/using-with-jest.md

@@ -1,81 +1,40 @@
-# Using with Jest
+Jest and Vue Test Utils work great together.
 
-## Setup Jest
+To get started, you need to install Jest and Vue Test Utils:
 
-Jest is a test runner developed by Facebook, aiming to come with everything included to get started. [Learn more about Jest](https://facebook.github.io/jest/)  So let's get started:
-
-```bash
-$ yarn add jest
 ```
-
-will install jest and makes it available to be executed through yarn or a package script.
-
-```json
-// package.json
-{
-  "scripts": {
-    "test": "jest"
-  }
-}
+npm install --save-dev jest vue-test-utils
 ```
 
-or
+Inside package.json, create an npm script that runs Jest:
 
-```bash
-$ yarn jest
 ```
-
-As you probably want to use latest javascript capabilities inside your specs though, it's recommendable to enable `babel` for the project.
-
-
-```bash
-$ yarn add babel babel-jest babel-preset-env
-```
-
-If you’ve not heard of babel-preset-env, it basically allows compiling the JS based on the browsers you plan to support. Get more info here: [babel-preset-env](https://github.com/babel/babel-preset-env)
-
-Be sure to update your `.babelrc` file accordingly
-
-```json
-{
-  "presets": [
-    ["env", {
-      "targets": {
-        "browsers": ["last 2 versions", "safari >= 7"]
-      }
-    }]
-  ]
+"scripts": {
+  "unit": "jest"
 }
 ```
 
-That's pretty much everything necessary to do before writing the first specs.
-
-### Where should my tests live
-
-By default, jest will pick up all files that have a `.spec.js` or `.test.js` extension. If this does not fit your needs, it's possible [to chang the testRegex](https://facebook.github.io/jest/docs/en/configuration.html#testregex-string) in the config section in the `package.json` file.
-
-Jest recommends to create a `__spec__` folder, but feel free to do as you like. Just know ahead of time, that when using the [snapshot](https://facebook.github.io/jest/docs/en/snapshot-testing.html#content) feature, snapshots will get stored in a `__snapshot__` folder.
-
-### Example Spec
-
-If you are familiar with Jasmine, or similar test libraries you should feel at home in Jest right away. Many useful assertions are in place, so
-enjoy writing specs.
+Add a `Component.spec.js` file:
 
 ```js
 import { mount } from 'vue-test-utils'
-import Component from './component'
+
+const Component = {
+  name: 'component',
+  render: (h) => h('div', 'Hello, World!')
+}
 
 describe('Component', () => {
-  test('is a Vue instance', () => {
+  test('renders "Hello, World!"', () => {
     const wrapper = mount(Component)
-    expect(wrapper.isVueInstance()).toBeTruthy()
+    expect(wrapper.text()).toBe('Hello, World!')
   })
 })
 ```
 
-### Resources
-
-- Examples and slides from Vue Conf 2017 - https://github.com/codebryo/vue-testing-with-jest-conf17
-- Jest - https://facebook.github.io/jest/
-- Babel preset env - https://github.com/babel/babel-preset-env
+And run the tests from the command line:
+```
+npm run unit
+```
 
+If you want to test .vue files, please see the testing SFCs with Jest guide.