Add jest-storybook to lib

lib/jest-storybook/README.md

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+# jest-storybook
+
+Jest implementation for Storybook.

lib/jest-storybook/package.json

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+{
+  "name": "jest-storybook",
+  "version": "1.0.0",
+  "description": "Jest implementation for Storybook",
+  "main": "src/jest.storybook.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/storybooks/storybook"
+  },
+  "keywords": [
+    "jest",
+    "storybook"
+  ],
+  "author": "evexoio (Abdullah Samman)",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/storybooks/storybook/issues"
+  },
+  "homepage": "https://github.com/storybooks/storybook",
+  "devDependencies": {
+    "babel-core": "^6.26.3",
+    "babel-preset-jest": "^23.2.0",
+    "falafel": "^2.1.0"
+  }
+}

lib/jest-storybook/src/jest.config.js.sample

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+module.exports = {
+  testMatch: ['**/*.stories.js'],
+  transform: {
+    '^.+\\.js$': 'jest-storybook',
+  },
+};

lib/jest-storybook/src/jest.storybook.js

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+const falafel = require('falafel'); // eslint-disable-line import/no-extraneous-dependencies
+const babel = require('babel-core');
+const jestPreset = require('babel-preset-jest');
+
+module.exports.process = (src, filename) => {
+  let output = falafel(src, { sourceType: 'module' }, (node) => { // AST just to import getStorybook. overkill?
+    if (node.type === 'ImportSpecifier' && node.imported.name === 'storiesOf') {
+      node.update(`${node.source()}, getStorybook`);
+    }
+  });
+
+  output = `
+import addons, { mockChannel } from '@storybook/addons';
+addons.setChannel(mockChannel());
+${output.toString()}
+const storybook = getStorybook();
+storybook.forEach((story) => {
+story.stories.forEach((subStory) => {
+describe(story.kind, () => {
+it(subStory.name, () => {
+expect(subStory.render()).toMatchSnapshot();
+}); }); }); });`;
+
+  if (babel.util.canCompile(filename)) {
+    src = babel.transform(output, {
+      filename,
+      presets: [jestPreset],
+    });
+  }
+
+  return src;
+};