def test_delta_t_hist():
    """Test histogram of all time lags."""
    times, values, errors = irregular_random()
    delta_ts = [pair[1] - pair[0] for pair in itertools.combinations(times, 2)]
    nbins = 50
    bins = np.linspace(0, max(times) - min(times), nbins+1)
    npt.assert_allclose(oft.delta_t_hist(times, nbins), np.histogram(delta_ts,
        bins=bins)[0])
def test_normalize_hist():
    """Test normalization of histogram."""
    times, values, errors = irregular_random()
    delta_ts = [pair[1] - pair[0] for pair in itertools.combinations(times, 2)]
    nbins = 50
    bins = np.linspace(0, max(times) - min(times), nbins+1)
    nhist = oft.normalize_hist(oft.delta_t_hist(times, nbins), max(times) -
                               min(times))
    npt.assert_allclose(nhist, np.histogram(delta_ts,
        bins=bins, density=True)[0])