'Fill in the form with the provided username and submit it.'

def fill_batch_beta_tester_addition_text_box(self, username):

    username_selector = '{}    textarea'.format(self.batch_beta_tester_selector)
    enrollment_button = "{}    .enrollment-button[data-action='add']".format(self.batch_beta_tester_selector)
    self.wait_for_element_visibility(username_selector, 'username    field    is    visible')
    self.q(css=username_selector).fill(username)
    self.wait_for_element_visibility(enrollment_button, 'Add    beta    testers    button')
    self.q(css=enrollment_button).click()
