Adds jest configuration npm run test shows failed results (#60)

examples/with-jest/__tests__/index.test.js

@@ -0,0 +1,12 @@
+
+import React from 'react';
+import {shallow} from 'enzyme';
+import App from '../pages/index.js';
+
+it('App shows "Hello world!"', () => {
+  const app = shallow(
+    <App/>
+  );
+
+  expect(app.find('p').text()).toEqual('Hello world!');
+});

examples/with-jest/package.json

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+{
+  "name": "my-app",
+  "dependencies": {
+    "next": "^1.0.0"
+  },
+  "scripts": {
+    "test": "jest",
+    "dev": "next",
+    "build": "next build",
+    "start": "next start"
+  },
+  "devDependencies": {
+    "babel-jest": "^16.0.0",
+    "enzyme": "^2.5.1",
+    "jest": "^16.0.2"
+  }
+}

examples/with-jest/pages/index.js

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+import React from 'react'
+export default () => (
+    <div>
+        <p>Hello world!</p>
+    </div>
+)

examples/with-jest/readme.md

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+## Add testing to your `next` app using `jest`
+
+[`jest`](https://facebook.github.io/jest/) is a testing framework for `react`. In this example we show how to use `jest` to do DOM-testing for react applications in `next`
+
+npm install --save-dev jest babel-jest enzyme
+
+ * `jest` - The testing framework
+ * `babel-jest` - Babel preprocessor for test files
+ * `enzyme` - Mock render the elements
+
+Add test script to the [recommended `package.json`](https://github.com/zeit/next.js#production-deployment)
+
+__package.json__
+
+```javascript
+...
+"scripts": {
+    "test": "jest",
+    ...
+}
+...
+
+```
+
+`npm run test`