setState in axios promise - no rerender

Question

Im trying to write task manager with mLab database. Im using axios http client. The problem is that when I'm trying to add a new task the app do not re-render I have to manually refresh the page to make it work.

class App extends Component {
  constructor() {
    super()

    this.state = {
      tasks: []
    }
  }

addTask(text) {
    axios.request({
      method: 'post',
      url: 'https://exampleAPIaddress',
      data: {
        text: text,
        completed: false
      }
    }).then(response => {

      let tasks = this.state.tasks;
      tasks.push({
        _id: response.data._id,
        text: text,
        completed: false
      })
      this.setState = ({
        tasks: tasks
      })
    }).catch((error) => {
      console.log(error)
    })
  }

render() {
    return (
          <AddTask onAddTask={this.addTask.bind(this)} />
    );
  }
}