old_contents: """Tests for main.py"""
  from ..main import _solve_weight_vector
  import numpy as np
  from nose.tools import assert_raises, assert_equal, assert_true
  
  
  def test_solve_weight_vector():
      # smoke test
      n_nodes = 4
      n_communities = 2
      n_similarities = 3
      delta = 0.3
      similarities = np.random.random((n_similarities,
                                       n_nodes * (n_nodes-1)/2)) * 10
      grouping_matrix = np.random.random((n_nodes, n_communities))
  
      weight = _solve_weight_vector(similarities, grouping_matrix, delta)
      assert_equal(weight.ndim, 2)
      assert_equal(weight.shape[1], n_similarities)
      assert_true(np.all(weight >= 0))
  
      # check raises
      assert_raises(ValueError,
                    _solve_weight_vector, similarities, grouping_matrix, -1)
      similarities_invalid = similarities.copy()
      similarities_invalid[0, 3] = -4.
      assert_raises(ValueError,
                    _solve_weight_vector, similarities_invalid,
                    grouping_matrix, delta)
  
new_contents: """Tests for main.py"""
  from ..main import _solve_weight_vector
  import numpy as np
  from numpy.testing import assert_array_almost_equal
  from nose.tools import assert_raises, assert_equal, assert_true
  
  
  def test_solve_weight_vector():
      # smoke test
      n_nodes = 4
      n_communities = 2
      n_similarities = 3
      delta = 0.3
      similarities = np.random.random((n_similarities,
                                       n_nodes * (n_nodes-1)/2)) * 10
      grouping_matrix = np.random.random((n_nodes, n_communities))
  
      weight = _solve_weight_vector(similarities, grouping_matrix, delta)
      assert_equal(weight.ndim, 2)
      assert_equal(weight.shape[1], n_similarities)
      assert_true(np.all(weight >= 0))
  
      # check raises
      assert_raises(ValueError,
                    _solve_weight_vector, similarities, grouping_matrix, -1)
      similarities_invalid = similarities.copy()
      similarities_invalid[0, 3] = -4.
      assert_raises(ValueError,
                    _solve_weight_vector, similarities_invalid,
                    grouping_matrix, delta)
  
      # if I have two similarities, and one is null + the grouping matrix is all
      # to all, and delta is 0 (no regularization), then I expect that the weight
      # vector is [1, 0]
      similarities = np.vstack((1000*np.ones((1, 6)),
                                np.zeros((1, 6))
                                ))
      grouping_matrix = np.ones((4, 4))
      delta = 1
      assert_array_almost_equal(np.atleast_2d([1., 0.]),
                                _solve_weight_vector(similarities,
                                                     grouping_matrix,
                                                     delta))
  
subject: Add a more semantic test