Return Promise from Assertions

[dmitry-zaets]

Return a promise from assertion to allow chaining of assertions and Promise-based async tests

Related issues:

• .toDispatchActions(..) not working properly!? redux-actions-assertions#16
• No access to created store redux-actions-assertions#24

Old usage (mocha + expect):

it('<test name>',(done)=>{
  expect(fetchData()).toDispatchActions(expectedActions, done);
});

New usage (mocha + expect):

it('<test name>',()=>{
  return expect(fetchData()).toDispatchActions(expectedActions).then(()=>{
    expect(api.fetch).toHaveBeenCalled('/url');
  });
});