text: import pytest
  from ploomber.tasks._upstream import Upstream
  
  
  def test_can_get_first():
      p = Upstream()
  
      p['a'] = 0
  
      assert p.first == 0
  
  
  def test_shows_warning_if_unused_parameters():
      p = Upstream()
  
      p['a'] = 0
      p['b'] = 1
  
      with pytest.warns(UserWarning):
          with p:
              p['a']
  