import numpy as np
import pytest

import pandas as pd
import pandas._testing as tm

from pandas.tseries import offsets


class TestPickle:
    @pytest.mark.parametrize("freq", ["D", "M", "Y"])
    def test_pickle_round_trip(self, freq, temp_file):
        idx = pd.PeriodIndex(["2016-05-16", "NaT", pd.NaT, np.nan], freq=freq)
        result = tm.round_trip_pickle(idx, temp_file)
        tm.assert_index_equal(result, idx)

    def test_pickle_freq(self, temp_file):
        # GH#2891
        prng = pd.period_range("1/1/2011", "1/1/2012", freq="M")
        new_prng = tm.round_trip_pickle(prng, temp_file)
        assert new_prng.freq == offsets.MonthEnd()
        assert new_prng.freqstr == "M"