old_contents: # coding: utf-8
  import os, sys
  sys.path.append(os.path.join(sys.path[0], '..'))
  
  from carlo import Model, ModelException
  import pytest
  
  def test_minimal_model():
      m = Model(('const', {'int': lambda: 42})).build()
      assert [('const', {'int': 42})] == m.create()
      m = Model(('const2', {'str': lambda: 'hello'})).build()
      assert [('const2', {'str': 'hello'})] == m.create()
  
  def test_model_with_multiple_entities():
      m = Model(
              ('first', {'name': lambda: 'elves'}),
              ('second', {'name': lambda: 'humans'})).build()
      assert [('first', {'name': 'elves'}),
              ('second', {'name': 'humans'})] == m.create()
  
  def test_model_with_multiple_params():
      m = Model(('human', {
          'head': lambda: 1,
          'hands': lambda: 2,
          'name': lambda: 'Hurin',
          })).build()
      assert [('human', {'head': 1, 'hands': 2, 'name': 'Hurin'})] == m.create()
  
  # error handling
  
  def test_same_enitities_should_throw_error():
      with pytest.raises(ModelException):
          Model(('first', {'int': lambda: 32}),
                ('first', {'it works': lambda: False})).build()
  
  def test_same_params_should_throw_error():
      pass
  
new_contents: # coding: utf-8
  import os, sys
  sys.path.append(os.path.join(sys.path[0], '..'))
  
  from carlo import Model, ModelException
  import pytest
  
  def test_minimal_model():
      m = Model(('const', {'int': lambda: 42})).build()
      assert [('const', {'int': 42})] == m.create()
      m = Model(('const2', {'str': lambda: 'hello'})).build()
      assert [('const2', {'str': 'hello'})] == m.create()
  
  def test_model_with_multiple_entities():
      m = Model(
              ('first', {'name': lambda: 'elves'}),
              ('second', {'name': lambda: 'humans'})).build()
      assert [('first', {'name': 'elves'}),
              ('second', {'name': 'humans'})] == m.create()
  
  def test_model_with_multiple_params():
      m = Model(('human', {
          'head': lambda: 1,
          'hands': lambda: 2,
          'name': lambda: 'Hurin',
          })).build()
      assert [('human', {'head': 1, 'hands': 2, 'name': 'Hurin'})] == m.create()
  
  # error handling
  
  def test_same_enitities_should_throw_error():
      with pytest.raises(ModelException):
          Model(('first', {'int': lambda: 32}),
                ('first', {'it works': lambda: False})).build()
  
subject: Remove redundant test