failed compile from test_helper

i wrote test_helper for testing my react components but every time i hit npm start and following errors come out.

> jsonplaceholder-client@0.0.1 test /Users/WOOJUNG/Desktop/jsonplaceholder-client
> mocha --compilers js:babel-core/register --require ./test/test_helper.js --recursive ./test

/Users/WOOJUNG/Desktop/jsonplaceholder-client/node_modules/babel-register/node_modules/babel-core/lib/transformation/file/index.js:573
      throw err;
      ^

SyntaxError: /Users/WOOJUNG/Desktop/jsonplaceholder-client/test/test_helper.js: Unexpected token (21:4)
  19 | function renderComponent(ComponentClass, props = {}, state = {}) {
  20 |   const componentInstance =  TestUtils.renderIntoDocument(
> 21 |     <Provider store={createStore(reducers, state)}>
     |     ^
  22 |       <ComponentClass {...props} />
  23 |     </Provider>
  24 |   );

it seems like error occurs because of failed compile test_helper. I'm not sure but as I know js:babel-core/register can compile es6 but it fails. should I give another options to compile test_helper? but I have no idea. T_ T