old_contents: from __future__ import absolute_import, division, print_function
  
  import unittest
  
  
  class TestKiwisolver(unittest.TestCase):
  
      # Minimal import test: we only added this package because it's a dependency of matplotlib.
      def test_basic(self):
          import kiwisolver  # noqa: F401
  
new_contents: import unittest
  
  
  class TestKiwisolver(unittest.TestCase):
  
      # From https://kiwisolver.readthedocs.io/en/latest/basis/basic_systems.html
      def test_basic(self):
          from kiwisolver import Solver, Variable
  
          x1 = Variable('x1')
          x2 = Variable('x2')
          xm = Variable('xm')
  
          constraints = [x1 >= 0, x2 <= 100, x2 >= x1 + 10, xm == (x1 + x2) / 2]
          solver = Solver()
          for cn in constraints:
              solver.addConstraint(cn)
  
          solver.addConstraint((x1 == 40) | "weak")
          solver.addEditVariable(xm, 'strong')
          solver.suggestValue(xm, 60)
          solver.updateVariables()
          self.assertEqual(60, xm.value())
          self.assertEqual(40, x1.value())
          self.assertEqual(80, x2.value())
  
subject: Add proper test for kiwisolver