new_contents: """
  Filename: test_distributions.py
  Author: Quentin Batista
  
  Tests for distributions.py
  
  """
  import numpy as np
  from numpy.testing import assert_allclose
  from nose.tools import eq_
  from math import sqrt
  from quantecon.distributions import BetaBinomial
  
  
  class TestBetaBinomial:
      def setUp(self):
          self.n = 100
          self.a = 5
          self.b = 5
          self.test_obj = BetaBinomial(self.n, self.a, self.b)
      
      def test_init(self):
          eq_(self.test_obj.n, self.n)
          eq_(self.test_obj.a, self.a)
          eq_(self.test_obj.b, self.b)
  
      def test_mean(self):
          eq_(self.test_obj.mean, 50)
  
      def test_std(self):
          eq_(self.test_obj.std, sqrt(250))
  
      def test_var(self):
          eq_(self.test_obj.var, 250)
  
      def test_skew(self):
          eq_(self.test_obj.skew, 0)
  
      def test_pdf(self):
          n = 9
          a = 1
          b = 1
          test_obj = BetaBinomial(n, a, b)
          assert_allclose(test_obj.pdf(), np.full(n+1, 1/(n+1)))
              
  
  if __name__ == '__main__':
      import sys
      import nose
  
      argv = sys.argv[:]
      argv.append('--verbose')
      argv.append('--nocapture')
      nose.main(argv=argv, defaultTest=__file__)
  
subject: Add tests for distributions.py (#324)