title: use babel-jest for jest but still get syntax error
body: <p>I am new to jest and want to test my react.js app.
  I am following a book, React.js Essentials for jest part. </p>
  
  <p>Here is my test code, Button-test.js</p>
  
  <pre><code>jest.dontMock('../Button.react');
  
  describe('Button component', function () {
    it('calls handler function on click', function () {
      var React = require('react');
      var TestUtils = require('react-addons-test-utils');
      var Button = require('../Button.react');
      var handleClick = jest.genMockFunction();
  
      var button = TestUtils.renderIntoDocument(
        &lt;Button handleClick={handleClick}/&gt;
      );
  
      var buttonInstance =
        TestUtils.findRenderedDOMComponentWithTag(button, 'button');
  
      TestUtils.Simulate.click(buttonInstance);
      expect(handleClick).toBeCalled();
      var numberOfCallsMadeIntoMockFunction =
        handleClick.mock.calls.length;
      expect(numberOfCallsMadeIntoMockFunction).toBe(1);
    });
  });
  </code></pre>
  
  <p>Here is my package.json</p>
  
  <pre><code>{
    "name": "snapterest",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "scripts": {
      "test": "jest"
    },
    "author": "",
    "license": "ISC",
    "devDependencies": {
      "babel-jest": "^6.0.1",
      "babelify": "^6.2.0",
      "browserify": "^12.0.1",
      "gulp": "^3.9.0",
      "jest-cli": "^0.8.0",
      "vinyl-source-stream": "^1.1.0"
    },
    "dependencies": {
      "react": "^0.14.0-beta3",
      "react-dom": "^0.14.0-beta3",
      "snapkite-stream-client": "^1.0.3"
    },
    "jest": {
      "scriptPreprocessor": "&lt;rootDir&gt;/node_modules/babel-jest",
      "testFileExtensions": ["es6", "js"],
      "unmockedModulePathPatterns": [
        "&lt;rootDir&gt;/node_modules/react"
      ]
    }
  }
  </code></pre>
  
  <p>The problem is, when I run npm test, it reports the following syntax error. I think babel-jest is installed, and I have no idea why the syntax error is still there. Are there anything else I need to do except installing babel-jest?</p>
  
  <pre><code>source/components/__tests__/Header-test.js 
  ● Runtime Error
  SyntaxError:        
  /snapterest/source/components/__tests__/Header-test.js: Unexpected token (11:6)
     9 |    
    10 |     var button = TestUtils.renderIntoDocument(
  &gt; 11 |       &lt;Button handleClick={handleClick}/&gt;
       |       ^
    12 |     );
  </code></pre>