Config Jest to mock static assets since they're not needed during test.

Ref: https://facebook.github.io/jest/docs/webpack.html#handling-static-assets

__mocks__/fileMock.js

@@ -0,0 +1 @@
+module.exports = 'mocked-file';

config/jest.config.json

@@ -0,0 +1,5 @@
+{
+    "moduleNameMapper": {
+         "\\.(css|scss|sass|md|jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|)$": "<rootDir>/__mocks__/fileMock.js"
+    }
+}

package.json

@@ -24,6 +24,7 @@
     "build:lib": "BABEL_ENV=lib babel src --out-dir lib",
     "build:es5": "BABEL_ENV=es5 babel src --out-dir es5",
     "lint": "eslint ./ && echo \"eslint: no lint errors\"",
+    "test": "jest ./src --config=config/jest.config.json",
     "clean": "rm -rf ./dist ./lib ./es5 ./deploy",
     "deploy": "npm run clean && npm run build && sh deploy.sh"
   },

src/__tests__/index.test.js

@@ -0,0 +1,8 @@
+import React from 'react';
+import ReactDOM from 'react-dom';
+import App from '../index';
+
+it('renders without crashing', () => {
+    const div = document.createElement('div');
+    ReactDOM.render(<App />, div);
+});