
import numpy as np
from numpy.testing import assert_almost_equal
from scipy import stats

from statsmodels.stats._lilliefors import lilliefors


class TestLilliefors(object):

    def test_normal(self):
        np.random.seed(3975)
        x_n = stats.norm.rvs(size=500)

        # R function call:
        # require(nortest)
        # lillie.test(x_n)

        d_ks_norm, p_norm = lilliefors(x_n, dist='norm')
        # shift normal distribution > 0 to exactly mirror R `KScorrect` test
        # R `KScorrect` requires all values tested for exponential
        # distribution to be > 0
        # R function call:
        # require(KScorrect)
        # LcKS(x_n+abs(min(x_n))+0.001, 'pexp')

        d_ks_exp, p_exp = lilliefors(x_n+np.abs(x_n.min()) + 0.001, dist='exp')
        # assert normal
        assert_almost_equal(d_ks_norm, 0.025957, decimal=3)
        assert_almost_equal(p_norm, 0.2000, decimal=3)
        # assert exp
        assert_almost_equal(d_ks_exp, 0.3436007, decimal=3)
        assert_almost_equal(p_exp, 0.01, decimal=3)

    def test_expon(self):
        np.random.seed(3975)
        x_e = stats.expon.rvs(size=500)
        # R function call:
        # require(nortest)
        # lillie.test(x_n)
        d_ks_norm, p_norm = lilliefors(x_e, dist='norm')
        # R function call:
        # require(KScorrect)
        # LcKS(x_e, 'pexp')
        d_ks_exp, p_exp = lilliefors(x_e, dist='exp')
        # assert normal
        assert_almost_equal(d_ks_norm, 0.15581, decimal=3)
        assert_almost_equal(p_norm, 2.2e-16, decimal=3)
        # assert exp
        assert_almost_equal(d_ks_exp, 0.02763748, decimal=3)
        assert_almost_equal(p_exp, 0.200, decimal=3)

    def test_pval_bounds(self):
        x = np.arange(1,10)
        d_ks_n, p_n = lilliefors(x, dist='norm')
        d_ks_e, p_e = lilliefors(x, dist='exp')

        assert_almost_equal(p_n, 0.200, decimal=7)
        assert_almost_equal(p_e, 0.200, decimal=7)
