it 'teaching assistant should not be able to impersonate an instructor with their real name' do
      stub_current_user(teaching_assistant, teaching_assistant.role.name, teaching_assistant.role)
      allow(User).to receive(:find_by).with(name: instructor.name).and_return(instructor)
      allow(teaching_assistant).to receive(:can_impersonate?).with(instructor).and_return(false)
      request.env['HTTP_REFERER'] = 'http://www.example.com'