new_contents: import pytest
  from anisotropy import UniaxialAnisotropy
  
  
  class TestUniaxialAnisotropy(object):
      def setup(self):
          # Set of valid arguments.
          self.args1 = [(1, (0, 1, 0)),
                        (5e6, (1, 1, 1)),
                        (-25.6e-3, (0, 0, 1))]
  
          # Set of invalid arguments.
          self.args2 = [('1', (0, 1, 0)),
                        (5e6, '(1, 1, 1)')]
  
      def test_init(self):
          # Valid arguments.
          for arg in self.args1:
              K1 = arg[0]
              axis = arg[1]
              anisotropy = UniaxialAnisotropy(K1, axis)
  
              assert anisotropy.K1 == K1
              assert isinstance(anisotropy.K1, (int, float))
              assert anisotropy.axis == axis
              assert isinstance(anisotropy.axis, (tuple, list))
  
      def test_init_exceptions(self):
          # Invalid arguments (ValueError expected).
          for arg in self.args2:
              K1 = arg[0]
              axis = arg[1]
              with pytest.raises(ValueError):
                  anisotropy = UniaxialAnisotropy(K1, axis)
  
      def test_get_mif(self):
          for arg in self.args1:
              K1 = arg[0]
              axis = arg[1]
  
              anisotropy = UniaxialAnisotropy(K1, axis)
  
              mif = anisotropy.get_mif()
              mif_lines = anisotropy.get_mif().split('\n')
  
              # Assert comment.
              l = mif_lines[0].split()
              assert l[0] == '#'
              assert l[1] == 'UniaxialAnisotropy'
  
              # Assert Specify line.
              l = mif_lines[1].split()
              assert l[0] == 'Specify'
              assert l[1] == 'Oxs_UniaxialAnisotropy'
              assert l[2] == '{'
  
              # Assert step line.
              assert mif_lines[2][0] == '\t'
              l = mif_lines[2].split()
              assert l[0] == 'K1'
              assert float(l[1]) == K1
  
              # Assert step line.
              assert mif_lines[3][0] == '\t'
              l = mif_lines[3].split()
              assert l[0] == 'axis'
              assert l[1] == '{'
              assert float(l[2]) == axis[0]
              assert float(l[3]) == axis[1]
              assert float(l[4]) == axis[2]
              assert l[5] == '}'
  
              # Assert mif end.
              assert mif_lines[4] == '}'
  
              # Assert new lines at the end of the string.
              assert mif[-2:] == '\n\n'
  
subject: Add anisotropy tests.