# Copyright (C) 2011 by Brandon Invergo (b.invergo@gmail.com)
# This code is part of the Biopython distribution and governed by its
# license. Please see the LICENSE file that should have been included
# as part of this package.

"""Tests for Chi2 module."""

import unittest
from Bio.Phylo.PAML import chi2


class ModTest(unittest.TestCase):
    def test_cdf_chi2(self):
        self.assertRaises(ValueError, chi2.cdf_chi2, df=0, stat=3.84)
        self.assertRaises(ValueError, chi2.cdf_chi2, df=1, stat=-3.84)
        self.assertRaises(TypeError, chi2.cdf_chi2, df="d", stat="stat")
        self.assertAlmostEqual(chi2.cdf_chi2(2, 3.84), 0.1466070, places=5)

    def test_ln_gamma(self):
        self.assertRaises(ValueError, chi2._ln_gamma_function, -1)
        self.assertAlmostEqual(chi2._ln_gamma_function(10), 12.80183, places=5)

    def test_incomplete_gamma(self):
        self.assertRaises(ValueError, chi2._incomplete_gamma, x=0.5, alpha=-1)
        self.assertAlmostEqual(chi2._incomplete_gamma(0.5, 0.5), 0.6826895, places=5)


if __name__ == "__main__":
    runner = unittest.TextTestRunner(verbosity=2)
    unittest.main(testRunner=runner)
