testbed/astropy__astropy/astropy/time/tests/test_basic.py

# Licensed under a 3-clause BSD style license - see LICENSE.rst


import copy
import functools
import datetime
from copy import deepcopy

import numpy as np
from numpy.testing import assert_allclose

from astropy.tests.helper import catch_warnings, pytest
from astropy.utils.exceptions import AstropyDeprecationWarning
from astropy.utils import isiterable
from astropy.time import Time, ScaleValueError, STANDARD_TIME_SCALES, TimeString, TimezoneInfo
from astropy.coordinates import EarthLocation
from astropy import units as u
from astropy import _erfa as erfa
from astropy.table import Column
try:
    import pytz
    HAS_PYTZ = True
except ImportError:
    HAS_PYTZ = False

allclose_jd = functools.partial(np.allclose, rtol=2. ** -52, atol=0)
allclose_jd2 = functools.partial(np.allclose, rtol=2. ** -52,
                                 atol=2. ** -52)  # 20 ps atol
allclose_sec = functools.partial(np.allclose, rtol=2. ** -52,
                                 atol=2. ** -52 * 24 * 3600)  # 20 ps atol
allclose_year = functools.partial(np.allclose, rtol=2. ** -52,
                                  atol=0.)  # 14 microsec at current epoch


def setup_function(func):
    func.FORMATS_ORIG = deepcopy(Time.FORMATS)


def teardown_function(func):
    Time.FORMATS.clear()
    Time.FORMATS.update(func.FORMATS_ORIG)


class TestBasic():
    """Basic tests stemming from initial example and API reference"""

    def test_simple(self):
        times = ['1999-01-01 00:00:00.123456789', '2010-01-01 00:00:00']
        t = Time(times, format='iso', scale='utc')
        assert (repr(t) == "<Time object: scale='utc' format='iso' "
                "value=['1999-01-01 00:00:00.123' '2010-01-01 00:00:00.000']>")
        assert allclose_jd(t.jd1, np.array([2451180., 2455198.]))
        assert allclose_jd2(t.jd2, np.array([-0.5+1.4288980208333335e-06,
                                             -0.50000000e+00]))

        # Set scale to TAI
        t = t.tai
        assert (repr(t) == "<Time object: scale='tai' format='iso' "
                "value=['1999-01-01 00:00:32.123' '2010-01-01 00:00:34.000']>")
        assert allclose_jd(t.jd1, np.array([2451180., 2455198.]))
        assert allclose_jd2(t.jd2, np.array([-0.5+0.00037179926839122024,
                                             -0.5+0.00039351851851851852]))

        # Get a new ``Time`` object which is referenced to the TT scale
        # (internal JD1 and JD1 are now with respect to TT scale)"""

        assert (repr(t.tt) == "<Time object: scale='tt' format='iso' "
                "value=['1999-01-01 00:01:04.307' '2010-01-01 00:01:06.184']>")

        # Get the representation of the ``Time`` object in a particular format
        # (in this case seconds since 1998.0).  This returns either a scalar or
        # array, depending on whether the input was a scalar or array"""

        assert allclose_sec(t.cxcsec, np.array([31536064.307456788, 378691266.18400002]))

    def test_different_dimensions(self):
        """Test scalars, vector, and higher-dimensions"""
        # scalar
        val, val1 = 2450000.0, 0.125
        t1 = Time(val, val1, format='jd')
        assert t1.isscalar is True and t1.shape == ()
        # vector
        val = np.arange(2450000., 2450010.)
        t2 = Time(val, format='jd')
        assert t2.isscalar is False and t2.shape == val.shape
        # explicitly check broadcasting for mixed vector, scalar.
        val2 = 0.
        t3 = Time(val, val2, format='jd')
        assert t3.isscalar is False and t3.shape == val.shape
        val2 = (np.arange(5.)/10.).reshape(5, 1)
        # now see if broadcasting to two-dimensional works
        t4 = Time(val, val2, format='jd')
        assert t4.isscalar is False
        assert t4.shape == np.broadcast(val, val2).shape

    @pytest.mark.parametrize('value', [2455197.5, [2455197.5]])
    def test_copy_time(self, value):
        """Test copying the values of a Time object by passing it into the
        Time initializer.
        """
        t = Time(value, format='jd', scale='utc')

        t2 = Time(t, copy=False)
        assert np.all(t.jd - t2.jd == 0)
        assert np.all((t - t2).jd == 0)
        assert t._time.jd1 is t2._time.jd1
        assert t._time.jd2 is t2._time.jd2

        t2 = Time(t, copy=True)
        assert np.all(t.jd - t2.jd == 0)
        assert np.all((t - t2).jd == 0)
        assert t._time.jd1 is not t2._time.jd1
        assert t._time.jd2 is not t2._time.jd2

        # Include initializers
        t2 = Time(t, format='iso', scale='tai', precision=1)
        assert t2.value == '2010-01-01 00:00:34.0'
        t2 = Time(t, format='iso', scale='tai', out_subfmt='date')
        assert t2.value == '2010-01-01'

    def test_getitem(self):
        """Test that Time objects holding arrays are properly subscriptable,
        set isscalar as appropriate, and also subscript delta_ut1_utc, etc."""

        mjd = np.arange(50000, 50010)
        t = Time(mjd, format='mjd', scale='utc', location=('45d', '50d'))
        t1 = t[3]
        assert t1.isscalar is True
        assert t1._time.jd1 == t._time.jd1[3]
        assert t1.location is t.location
        t1a = Time(mjd[3], format='mjd', scale='utc')
        assert t1a.isscalar is True
        assert np.all(t1._time.jd1 == t1a._time.jd1)
        t1b = Time(t[3])
        assert t1b.isscalar is True
        assert np.all(t1._time.jd1 == t1b._time.jd1)
        t2 = t[4:6]
        assert t2.isscalar is False
        assert np.all(t2._time.jd1 == t._time.jd1[4:6])
        assert t2.location is t.location
        t2a = Time(t[4:6])
        assert t2a.isscalar is False
        assert np.all(t2a._time.jd1 == t._time.jd1[4:6])
        t2b = Time([t[4], t[5]])
        assert t2b.isscalar is False
        assert np.all(t2b._time.jd1 == t._time.jd1[4:6])
        t2c = Time((t[4], t[5]))
        assert t2c.isscalar is False
        assert np.all(t2c._time.jd1 == t._time.jd1[4:6])
        t.delta_tdb_tt = np.arange(len(t))  # Explicitly set (not testing .tdb)
        t3 = t[4:6]
        assert np.all(t3._delta_tdb_tt == t._delta_tdb_tt[4:6])
        t4 = Time(mjd, format='mjd', scale='utc',
                  location=(np.arange(len(mjd)), np.arange(len(mjd))))
        t5 = t4[3]
        assert t5.location == t4.location[3]
        t6 = t4[4:6]
        assert np.all(t6.location == t4.location[4:6])
        # check it is a view
        # (via ndarray, since quantity setter problematic for structured array)
        allzeros = np.array((0., 0., 0.), dtype=t4.location.dtype)
        assert t6.location.view(np.ndarray)[-1] != allzeros
        assert t4.location.view(np.ndarray)[5] != allzeros
        t6.location.view(np.ndarray)[-1] = allzeros
        assert t4.location.view(np.ndarray)[5] == allzeros
        # Test subscription also works for two-dimensional arrays.
        frac = np.arange(0., 0.999, 0.2)
        t7 = Time(mjd[:, np.newaxis] + frac, format='mjd', scale='utc',
                  location=('45d', '50d'))
        assert t7[0, 0]._time.jd1 == t7._time.jd1[0, 0]
        assert t7[0, 0].isscalar is True
        assert np.all(t7[5]._time.jd1 == t7._time.jd1[5])
        assert np.all(t7[5]._time.jd2 == t7._time.jd2[5])
        assert np.all(t7[:, 2]._time.jd1 == t7._time.jd1[:, 2])
        assert np.all(t7[:, 2]._time.jd2 == t7._time.jd2[:, 2])
        assert np.all(t7[:, 0]._time.jd1 == t._time.jd1)
        assert np.all(t7[:, 0]._time.jd2 == t._time.jd2)
        # Get tdb to check that delta_tdb_tt attribute is sliced properly.
        t7_tdb = t7.tdb
        assert t7_tdb[0, 0].delta_tdb_tt == t7_tdb.delta_tdb_tt[0, 0]
        assert np.all(t7_tdb[5].delta_tdb_tt == t7_tdb.delta_tdb_tt[5])
        assert np.all(t7_tdb[:, 2].delta_tdb_tt == t7_tdb.delta_tdb_tt[:, 2])
        # Explicitly set delta_tdb_tt attribute. Now it should not be sliced.
        t7.delta_tdb_tt = 0.1
        t7_tdb2 = t7.tdb
        assert t7_tdb2[0, 0].delta_tdb_tt == 0.1
        assert t7_tdb2[5].delta_tdb_tt == 0.1
        assert t7_tdb2[:, 2].delta_tdb_tt == 0.1
        # Check broadcasting of location.
        t8 = Time(mjd[:, np.newaxis] + frac, format='mjd', scale='utc',
                  location=(np.arange(len(frac)), np.arange(len(frac))))
        assert t8[0, 0].location == t8.location[0, 0]
        assert np.all(t8[5].location == t8.location[5])
        assert np.all(t8[:, 2].location == t8.location[:, 2])
        # Finally check empty array.
        t9 = t[:0]
        assert t9.isscalar is False
        assert t9.shape == (0,)
        assert t9.size == 0

    def test_properties(self):
        """Use properties to convert scales and formats.  Note that the UT1 to
        UTC transformation requires a supplementary value (``delta_ut1_utc``)
        that can be obtained by interpolating from a table supplied by IERS.
        This is tested separately."""

        t = Time('2010-01-01 00:00:00', format='iso', scale='utc')
        t.delta_ut1_utc = 0.3341  # Explicitly set one part of the xform
        assert allclose_jd(t.jd, 2455197.5)
        assert t.iso == '2010-01-01 00:00:00.000'
        assert t.tt.iso == '2010-01-01 00:01:06.184'
        assert t.tai.fits == '2010-01-01T00:00:34.000'
        assert allclose_jd(t.utc.jd, 2455197.5)
        assert allclose_jd(t.ut1.jd, 2455197.500003867)
        assert t.tcg.isot == '2010-01-01T00:01:06.910'
        assert allclose_sec(t.unix, 1262304000.0)
        assert allclose_sec(t.cxcsec, 378691266.184)
        assert allclose_sec(t.gps, 946339215.0)
        assert t.datetime == datetime.datetime(2010, 1, 1)

    def test_precision(self):
        """Set the output precision which is used for some formats.  This is
        also a test of the code that provides a dict for global and instance
        options."""

        t = Time('2010-01-01 00:00:00', format='iso', scale='utc')
        # Uses initial class-defined precision=3
        assert t.iso == '2010-01-01 00:00:00.000'

        # Set instance precision to 9
        t.precision = 9
        assert t.iso == '2010-01-01 00:00:00.000000000'
        assert t.tai.utc.iso == '2010-01-01 00:00:00.000000000'

    def test_transforms(self):
        """Transform from UTC to all supported time scales (TAI, TCB, TCG,
        TDB, TT, UT1, UTC).  This requires auxiliary information (latitude and
        longitude)."""

        lat = 19.48125
        lon = -155.933222
        t = Time('2006-01-15 21:24:37.5', format='iso', scale='utc',
                 precision=6, location=(lon, lat))
        t.delta_ut1_utc = 0.3341  # Explicitly set one part of the xform
        assert t.utc.iso == '2006-01-15 21:24:37.500000'
        assert t.ut1.iso == '2006-01-15 21:24:37.834100'
        assert t.tai.iso == '2006-01-15 21:25:10.500000'
        assert t.tt.iso == '2006-01-15 21:25:42.684000'
        assert t.tcg.iso == '2006-01-15 21:25:43.322690'
        assert t.tdb.iso == '2006-01-15 21:25:42.684373'
        assert t.tcb.iso == '2006-01-15 21:25:56.893952'

    def test_location(self):
        """Check that location creates an EarthLocation object, and that
        such objects can be used as arguments.
        """
        lat = 19.48125
        lon = -155.933222
        t = Time(['2006-01-15 21:24:37.5'], format='iso', scale='utc',
                 precision=6, location=(lon, lat))
        assert isinstance(t.location, EarthLocation)
        location = EarthLocation(lon, lat)
        t2 = Time(['2006-01-15 21:24:37.5'], format='iso', scale='utc',
                  precision=6, location=location)
        assert isinstance(t2.location, EarthLocation)
        assert t2.location == t.location
        t3 = Time(['2006-01-15 21:24:37.5'], format='iso', scale='utc',
                  precision=6, location=(location.x, location.y, location.z))
        assert isinstance(t3.location, EarthLocation)
        assert t3.location == t.location

    def test_location_array(self):
        """Check that location arrays are checked for size and used
        for the corresponding times.  Also checks that erfa
        can handle array-valued locations, and can broadcast these if needed.
        """

        lat = 19.48125
        lon = -155.933222
        t = Time(['2006-01-15 21:24:37.5']*2, format='iso', scale='utc',
                 precision=6, location=(lon, lat))
        assert np.all(t.utc.iso == '2006-01-15 21:24:37.500000')
        assert np.all(t.tdb.iso[0] == '2006-01-15 21:25:42.684373')
        t2 = Time(['2006-01-15 21:24:37.5']*2, format='iso', scale='utc',
                  precision=6, location=(np.array([lon, 0]),
                                         np.array([lat, 0])))
        assert np.all(t2.utc.iso == '2006-01-15 21:24:37.500000')
        assert t2.tdb.iso[0] == '2006-01-15 21:25:42.684373'
        assert t2.tdb.iso[1] != '2006-01-15 21:25:42.684373'
        with pytest.raises(ValueError):  # 1 time, but two locations
            Time('2006-01-15 21:24:37.5', format='iso', scale='utc',
                 precision=6, location=(np.array([lon, 0]),
                                        np.array([lat, 0])))
        with pytest.raises(ValueError):  # 3 times, but two locations
            Time(['2006-01-15 21:24:37.5']*3, format='iso', scale='utc',
                 precision=6, location=(np.array([lon, 0]),
                                        np.array([lat, 0])))
        # multidimensional
        mjd = np.arange(50000., 50008.).reshape(4, 2)
        t3 = Time(mjd, format='mjd', scale='utc', location=(lon, lat))
        assert t3.shape == (4, 2)
        assert t3.location.shape == ()
        assert t3.tdb.shape == t3.shape
        t4 = Time(mjd, format='mjd', scale='utc',
                  location=(np.array([lon, 0]), np.array([lat, 0])))
        assert t4.shape == (4, 2)
        assert t4.location.shape == t4.shape
        assert t4.tdb.shape == t4.shape
        t5 = Time(mjd, format='mjd', scale='utc',
                  location=(np.array([[lon], [0], [0], [0]]),
                            np.array([[lat], [0], [0], [0]])))
        assert t5.shape == (4, 2)
        assert t5.location.shape == t5.shape
        assert t5.tdb.shape == t5.shape

    def test_all_scale_transforms(self):
        """Test that standard scale transforms work.  Does not test correctness,
        except reversibility [#2074]. Also tests that standard scales can't be
        converted to local scales"""
        lat = 19.48125
        lon = -155.933222
        for scale1 in STANDARD_TIME_SCALES:
            t1 = Time('2006-01-15 21:24:37.5', format='iso', scale=scale1,
                      location=(lon, lat))
            for scale2 in STANDARD_TIME_SCALES:
                t2 = getattr(t1, scale2)
                t21 = getattr(t2, scale1)
                assert allclose_jd(t21.jd, t1.jd)

            # test for conversion to local scale
            scale3 = 'local'
            with pytest.raises(ScaleValueError):
                t2 = getattr(t1, scale3)

    def test_creating_all_formats(self):
        """Create a time object using each defined format"""
        Time(2000.5, format='decimalyear')
        Time(100.0, format='cxcsec')
        Time(100.0, format='unix')
        Time(100.0, format='gps')
        Time(1950.0, format='byear', scale='tai')
        Time(2000.0, format='jyear', scale='tai')
        Time('B1950.0', format='byear_str', scale='tai')
        Time('J2000.0', format='jyear_str', scale='tai')
        Time('2000-01-01 12:23:34.0', format='iso', scale='tai')
        Time('2000-01-01 12:23:34.0Z', format='iso', scale='utc')
        Time('2000-01-01T12:23:34.0', format='isot', scale='tai')
        Time('2000-01-01T12:23:34.0Z', format='isot', scale='utc')
        Time('2000-01-01T12:23:34.0', format='fits')
        Time('2000-01-01T12:23:34.0', format='fits', scale='tdb')
        Time(2400000.5, 51544.0333981, format='jd', scale='tai')
        Time(0.0, 51544.0333981, format='mjd', scale='tai')
        Time('2000:001:12:23:34.0', format='yday', scale='tai')
        Time('2000:001:12:23:34.0Z', format='yday', scale='utc')
        dt = datetime.datetime(2000, 1, 2, 3, 4, 5, 123456)
        Time(dt, format='datetime', scale='tai')
        Time([dt, dt], format='datetime', scale='tai')
        dt64 = np.datetime64('2012-06-18T02:00:05.453000000', format='datetime64')
        Time(dt64, format='datetime64', scale='tai')
        Time([dt64, dt64], format='datetime64', scale='tai')

    def test_local_format_transforms(self):
        """
        Test trasformation of local time to different formats
        Transformation to formats with reference time should give
        ScalevalueError
        """
        t = Time('2006-01-15 21:24:37.5', scale='local')
        assert_allclose(t.jd, 2453751.3921006946, atol=0.001/3600./24., rtol=0.)
        assert_allclose(t.mjd, 53750.892100694444, atol=0.001/3600./24., rtol=0.)
        assert_allclose(t.decimalyear, 2006.0408002758752, atol=0.001/3600./24./365., rtol=0.)
        assert t.datetime == datetime.datetime(2006, 1, 15, 21, 24, 37, 500000)
        assert t.isot == '2006-01-15T21:24:37.500'
        assert t.yday == '2006:015:21:24:37.500'
        assert t.fits == '2006-01-15T21:24:37.500'
        assert_allclose(t.byear, 2006.04217888831, atol=0.001/3600./24./365., rtol=0.)
        assert_allclose(t.jyear, 2006.0407723496082, atol=0.001/3600./24./365., rtol=0.)
        assert t.byear_str == 'B2006.042'
        assert t.jyear_str == 'J2006.041'

        # epochTimeFormats
        with pytest.raises(ScaleValueError):
            t2 = t.gps
        with pytest.raises(ScaleValueError):
            t2 = t.unix
        with pytest.raises(ScaleValueError):
            t2 = t.cxcsec
        with pytest.raises(ScaleValueError):
            t2 = t.plot_date

    def test_datetime(self):
        """
        Test datetime format, including guessing the format from the input type
        by not providing the format keyword to Time.
        """
        dt = datetime.datetime(2000, 1, 2, 3, 4, 5, 123456)
        dt2 = datetime.datetime(2001, 1, 1)
        t = Time(dt, scale='utc', precision=9)
        assert t.iso == '2000-01-02 03:04:05.123456000'
        assert t.datetime == dt
        assert t.value == dt
        t2 = Time(t.iso, scale='utc')
        assert t2.datetime == dt

        t = Time([dt, dt2], scale='utc')
        assert np.all(t.value == [dt, dt2])

        t = Time('2000-01-01 01:01:01.123456789', scale='tai')
        assert t.datetime == datetime.datetime(2000, 1, 1, 1, 1, 1, 123457)

        # broadcasting
        dt3 = (dt + (dt2-dt)*np.arange(12)).reshape(4, 3)
        t3 = Time(dt3, scale='utc')
        assert t3.shape == (4, 3)
        assert t3[2, 1].value == dt3[2, 1]
        assert t3[2, 1] == Time(dt3[2, 1])
        assert np.all(t3.value == dt3)
        assert np.all(t3[1].value == dt3[1])
        assert np.all(t3[:, 2] == Time(dt3[:, 2]))
        assert Time(t3[2, 0]) == t3[2, 0]

    def test_datetime64(self):
        dt64 = np.datetime64('2000-01-02T03:04:05.123456789')
        dt64_2 = np.datetime64('2000-01-02')
        t = Time(dt64, scale='utc', precision=9, format='datetime64')
        assert t.iso == '2000-01-02 03:04:05.123456789'
        assert t.datetime64 == dt64
        assert t.value == dt64
        t2 = Time(t.iso, scale='utc')
        assert t2.datetime64 == dt64

        t = Time(dt64_2, scale='utc', precision=3, format='datetime64')
        assert t.iso == '2000-01-02 00:00:00.000'
        assert t.datetime64 == dt64_2
        assert t.value == dt64_2
        t2 = Time(t.iso, scale='utc')
        assert t2.datetime64 == dt64_2

        t = Time([dt64, dt64_2], scale='utc', format='datetime64')
        assert np.all(t.value == [dt64, dt64_2])

        t = Time('2000-01-01 01:01:01.123456789', scale='tai')
        assert t.datetime64 == np.datetime64('2000-01-01T01:01:01.123456789')

        # broadcasting
        dt3 = (dt64 + (dt64_2-dt64)*np.arange(12)).reshape(4, 3)
        t3 = Time(dt3, scale='utc', format='datetime64')
        assert t3.shape == (4, 3)
        assert t3[2, 1].value == dt3[2, 1]
        assert t3[2, 1] == Time(dt3[2, 1], format='datetime64')
        assert np.all(t3.value == dt3)
        assert np.all(t3[1].value == dt3[1])
        assert np.all(t3[:, 2] == Time(dt3[:, 2], format='datetime64'))
        assert Time(t3[2, 0], format='datetime64') == t3[2, 0]

    def test_epoch_transform(self):
        """Besselian and julian epoch transforms"""
        jd = 2457073.05631
        t = Time(jd, format='jd', scale='tai', precision=6)
        assert allclose_year(t.byear, 2015.1365941020817)
        assert allclose_year(t.jyear, 2015.1349933196439)
        assert t.byear_str == 'B2015.136594'
        assert t.jyear_str == 'J2015.134993'
        t2 = Time(t.byear, format='byear', scale='tai')
        assert allclose_jd(t2.jd, jd)
        t2 = Time(t.jyear, format='jyear', scale='tai')
        assert allclose_jd(t2.jd, jd)

        t = Time('J2015.134993', scale='tai', precision=6)
        assert np.allclose(t.jd, jd, rtol=1e-10, atol=0)  # J2015.134993 has 10 digit precision
        assert t.byear_str == 'B2015.136594'

    def test_input_validation(self):
        """Wrong input type raises error"""
        times = [10, 20]
        with pytest.raises(ValueError):
            Time(times, format='iso', scale='utc')
        with pytest.raises(ValueError):
            Time('2000:001', format='jd', scale='utc')
        with pytest.raises(ValueError):
            Time([50000.0], ['bad'], format='mjd', scale='tai')
        with pytest.raises(ValueError):
            Time(50000.0, 'bad', format='mjd', scale='tai')
        with pytest.raises(ValueError):
            Time('2005-08-04T00:01:02.000Z', scale='tai')
        # regression test against #3396
        with pytest.raises(ValueError):
            Time(np.nan, format='jd', scale='utc')
        with pytest.raises(ValueError):
            Time('2000-01-02T03:04:05(TAI)', scale='utc')
        with pytest.raises(ValueError):
            Time('2000-01-02T03:04:05(TAI')
        with pytest.raises(ValueError):
            Time('2000-01-02T03:04:05(UT(NIST)')

    def test_utc_leap_sec(self):
        """Time behaves properly near or in UTC leap second.  This
        uses the 2012-06-30 leap second for testing."""
        for year, month, day in ((2012, 6, 30), (2016, 12, 31)):
            # Start with a day without a leap second and note rollover
            yyyy_mm = '{:04d}-{:02d}'.format(year, month)
            yyyy_mm_dd = '{:04d}-{:02d}-{:02d}'.format(year, month, day)
            t1 = Time(yyyy_mm + '-01 23:59:60.0', scale='utc')
            assert t1.iso == yyyy_mm + '-02 00:00:00.000'

            # Leap second is different
            t1 = Time(yyyy_mm_dd + ' 23:59:59.900', scale='utc')
            assert t1.iso == yyyy_mm_dd + ' 23:59:59.900'

            t1 = Time(yyyy_mm_dd + ' 23:59:60.000', scale='utc')
            assert t1.iso == yyyy_mm_dd + ' 23:59:60.000'

            t1 = Time(yyyy_mm_dd + ' 23:59:60.999', scale='utc')
            assert t1.iso == yyyy_mm_dd + ' 23:59:60.999'

            if month == 6:
                yyyy_mm_dd_plus1 = '{:04d}-07-01'.format(year)
            else:
                yyyy_mm_dd_plus1 = '{:04d}-01-01'.format(year+1)

            t1 = Time(yyyy_mm_dd + ' 23:59:61.0', scale='utc')
            assert t1.iso == yyyy_mm_dd_plus1 + ' 00:00:00.000'

            # Delta time gives 2 seconds here as expected
            t0 = Time(yyyy_mm_dd + ' 23:59:59', scale='utc')
            t1 = Time(yyyy_mm_dd_plus1 + ' 00:00:00', scale='utc')
            assert allclose_sec((t1 - t0).sec, 2.0)

    def test_init_from_time_objects(self):
        """Initialize from one or more Time objects"""
        t1 = Time('2007:001', scale='tai')
        t2 = Time(['2007-01-02', '2007-01-03'], scale='utc')
        # Init from a list of Time objects without an explicit scale
        t3 = Time([t1, t2])
        # Test that init appropriately combines a scalar (t1) and list (t2)
        # and that scale and format are same as first element.
        assert len(t3) == 3
        assert t3.scale == t1.scale
        assert t3.format == t1.format  # t1 format is yday
        assert np.all(t3.value == np.concatenate([[t1.yday], t2.tai.yday]))

        # Init from a single Time object without a scale
        t3 = Time(t1)
        assert t3.isscalar
        assert t3.scale == t1.scale
        assert t3.format == t1.format
        assert np.all(t3.value == t1.value)

        # Init from a single Time object with scale specified
        t3 = Time(t1, scale='utc')
        assert t3.scale == 'utc'
        assert np.all(t3.value == t1.utc.value)

        # Init from a list of Time object with scale specified
        t3 = Time([t1, t2], scale='tt')
        assert t3.scale == 'tt'
        assert t3.format == t1.format  # yday
        assert np.all(t3.value == np.concatenate([[t1.tt.yday], t2.tt.yday]))

        # OK, how likely is this... but might as well test.
        mjd = np.arange(50000., 50006.)
        frac = np.arange(0., 0.999, 0.2)
        t4 = Time(mjd[:, np.newaxis] + frac, format='mjd', scale='utc')
        t5 = Time([t4[:2], t4[4:5]])
        assert t5.shape == (3, 5)

        # throw error when deriving local scale time
        # from non local time scale
        with pytest.raises(ValueError):
            t6 = Time(t1, scale='local')


class TestVal2():
    """Tests related to val2"""

    def test_val2_ignored(self):
        """Test that val2 is ignored for string input"""
        t = Time('2001:001', 'ignored', scale='utc')
        assert t.yday == '2001:001:00:00:00.000'

    def test_val2(self):
        """Various tests of the val2 input"""
        t = Time([0.0, 50000.0], [50000.0, 0.0], format='mjd', scale='tai')
        assert t.mjd[0] == t.mjd[1]
        assert t.jd[0] == t.jd[1]

    def test_val_broadcasts_against_val2(self):
        mjd = np.arange(50000., 50007.)
        frac = np.arange(0., 0.999, 0.2)
        t = Time(mjd[:, np.newaxis], frac, format='mjd', scale='utc')
        assert t.shape == (7, 5)
        with pytest.raises(ValueError):
            Time([0.0, 50000.0], [0.0, 1.0, 2.0], format='mjd', scale='tai')


class TestSubFormat():
    """Test input and output subformat functionality"""

    def test_input_subformat(self):
        """Input subformat selection"""
        # Heterogeneous input formats with in_subfmt='*' (default)
        times = ['2000-01-01', '2000-01-01 01:01',
                 '2000-01-01 01:01:01', '2000-01-01 01:01:01.123']
        t = Time(times, format='iso', scale='tai')
        assert np.all(t.iso == np.array(['2000-01-01 00:00:00.000',
                                         '2000-01-01 01:01:00.000',
                                         '2000-01-01 01:01:01.000',
                                         '2000-01-01 01:01:01.123']))

        # Heterogeneous input formats with in_subfmt='date_*'
        times = ['2000-01-01 01:01',
                 '2000-01-01 01:01:01', '2000-01-01 01:01:01.123']
        t = Time(times, format='iso', scale='tai',
                 in_subfmt='date_*')
        assert np.all(t.iso == np.array(['2000-01-01 01:01:00.000',
                                         '2000-01-01 01:01:01.000',
                                         '2000-01-01 01:01:01.123']))

    def test_input_subformat_fail(self):
        """Failed format matching"""
        with pytest.raises(ValueError):
            Time('2000-01-01 01:01', format='iso', scale='tai',
                 in_subfmt='date')

    def test_bad_input_subformat(self):
        """Non-existent input subformat"""
        with pytest.raises(ValueError):
            Time('2000-01-01 01:01', format='iso', scale='tai',
                 in_subfmt='doesnt exist')

    def test_output_subformat(self):
        """Input subformat selection"""
        # Heterogeneous input formats with in_subfmt='*' (default)
        times = ['2000-01-01', '2000-01-01 01:01',
                 '2000-01-01 01:01:01', '2000-01-01 01:01:01.123']
        t = Time(times, format='iso', scale='tai',
                 out_subfmt='date_hm')
        assert np.all(t.iso == np.array(['2000-01-01 00:00',
                                         '2000-01-01 01:01',
                                         '2000-01-01 01:01',
                                         '2000-01-01 01:01']))

    def test_fits_format(self):
        """FITS format includes bigger years."""
        # Heterogeneous input formats with in_subfmt='*' (default)
        times = ['2000-01-01', '2000-01-01T01:01:01', '2000-01-01T01:01:01.123']
        t = Time(times, format='fits', scale='tai')
        assert np.all(t.fits == np.array(['2000-01-01T00:00:00.000',
                                          '2000-01-01T01:01:01.000',
                                          '2000-01-01T01:01:01.123']))
        # Explicit long format for output, default scale is UTC.
        t2 = Time(times, format='fits', out_subfmt='long*')
        assert np.all(t2.fits == np.array(['+02000-01-01T00:00:00.000',
                                           '+02000-01-01T01:01:01.000',
                                           '+02000-01-01T01:01:01.123']))
        # Implicit long format for output, because of negative year.
        times[2] = '-00594-01-01'
        t3 = Time(times, format='fits', scale='tai')
        assert np.all(t3.fits == np.array(['+02000-01-01T00:00:00.000',
                                           '+02000-01-01T01:01:01.000',
                                           '-00594-01-01T00:00:00.000']))
        # Implicit long format for output, because of large positive year.
        times[2] = '+10594-01-01'
        t4 = Time(times, format='fits', scale='tai')
        assert np.all(t4.fits == np.array(['+02000-01-01T00:00:00.000',
                                           '+02000-01-01T01:01:01.000',
                                           '+10594-01-01T00:00:00.000']))

    def test_yday_format(self):
        """Year:Day_of_year format"""
        # Heterogeneous input formats with in_subfmt='*' (default)
        times = ['2000-12-01', '2001-12-01 01:01:01.123']
        t = Time(times, format='iso', scale='tai')
        t.out_subfmt = 'date_hm'
        assert np.all(t.yday == np.array(['2000:336:00:00',
                                          '2001:335:01:01']))
        t.out_subfmt = '*'
        assert np.all(t.yday == np.array(['2000:336:00:00:00.000',
                                          '2001:335:01:01:01.123']))

    def test_scale_input(self):
        """Test for issues related to scale input"""
        # Check case where required scale is defined by the TimeFormat.
        # All three should work.
        t = Time(100.0, format='cxcsec', scale='utc')
        assert t.scale == 'utc'
        t = Time(100.0, format='unix', scale='tai')
        assert t.scale == 'tai'
        t = Time(100.0, format='gps', scale='utc')
        assert t.scale == 'utc'

        # Check that bad scale is caught when format is specified
        with pytest.raises(ScaleValueError):
            Time(1950.0, format='byear', scale='bad scale')

        # Check that bad scale is caught when format is auto-determined
        with pytest.raises(ScaleValueError):
            Time('2000:001:00:00:00', scale='bad scale')

    def test_fits_scale(self):
        """Test that the previous FITS-string formatting can still be handled
        but with a DeprecationWarning."""
        for inputs in (("2000-01-02(TAI)", "tai"),
                       ("1999-01-01T00:00:00.123(ET(NIST))", "tt"),
                       ("2014-12-12T01:00:44.1(UTC)", "utc")):
            with catch_warnings(AstropyDeprecationWarning):
                t = Time(inputs[0])
            assert t.scale == inputs[1]

            # Create Time using normal ISOT syntax and compare with FITS
            t2 = Time(inputs[0][:inputs[0].index("(")], format="isot",
                      scale=inputs[1])
            assert t == t2

        # Explicit check that conversions still work despite warning
        with catch_warnings(AstropyDeprecationWarning):
            t = Time('1999-01-01T00:00:00.123456789(UTC)')
        t = t.tai
        assert t.isot == '1999-01-01T00:00:32.123'

        with catch_warnings(AstropyDeprecationWarning):
            t = Time('1999-01-01T00:00:32.123456789(TAI)')
        t = t.utc
        assert t.isot == '1999-01-01T00:00:00.123'

        # Check scale consistency
        with catch_warnings(AstropyDeprecationWarning):
            t = Time('1999-01-01T00:00:32.123456789(TAI)', scale="tai")
        assert t.scale == "tai"
        with catch_warnings(AstropyDeprecationWarning):
            t = Time('1999-01-01T00:00:32.123456789(ET)', scale="tt")
        assert t.scale == "tt"
        with pytest.raises(ValueError):
            t = Time('1999-01-01T00:00:32.123456789(TAI)', scale="utc")

    def test_scale_default(self):
        """Test behavior when no scale is provided"""
        # These first three are TimeFromEpoch and have an intrinsic time scale
        t = Time(100.0, format='cxcsec')
        assert t.scale == 'tt'
        t = Time(100.0, format='unix')
        assert t.scale == 'utc'
        t = Time(100.0, format='gps')
        assert t.scale == 'tai'

        for date in ('2000:001', '2000-01-01T00:00:00'):
            t = Time(date)
            assert t.scale == 'utc'

        t = Time(2000.1, format='byear')
        assert t.scale == 'tt'
        t = Time('J2000')
        assert t.scale == 'tt'

    def test_epoch_times(self):
        """Test time formats derived from EpochFromTime"""
        t = Time(0.0, format='cxcsec', scale='tai')
        assert t.tt.iso == '1998-01-01 00:00:00.000'

        # Create new time object from this one and change scale, format
        t2 = Time(t, scale='tt', format='iso')
        assert t2.value == '1998-01-01 00:00:00.000'

        # Value take from Chandra.Time.DateTime('2010:001:00:00:00').secs
        t_cxcsec = 378691266.184
        t = Time(t_cxcsec, format='cxcsec', scale='utc')
        assert allclose_sec(t.value, t_cxcsec)
        assert allclose_sec(t.cxcsec, t_cxcsec)
        assert allclose_sec(t.tt.value, t_cxcsec)
        assert allclose_sec(t.tt.cxcsec, t_cxcsec)
        assert t.yday == '2010:001:00:00:00.000'
        t = Time('2010:001:00:00:00.000', scale='utc')
        assert allclose_sec(t.cxcsec, t_cxcsec)
        assert allclose_sec(t.tt.cxcsec, t_cxcsec)

        # Value from:
        #   d = datetime.datetime(2000, 1, 1)
        #   matplotlib.pylab.dates.date2num(d)
        t = Time('2000-01-01 00:00:00', scale='utc')
        assert np.allclose(t.plot_date, 730120.0, atol=1e-5, rtol=0)

        # Round trip through epoch time
        for scale in ('utc', 'tt'):
            t = Time('2000:001', scale=scale)
            t2 = Time(t.unix, scale=scale, format='unix')
            assert getattr(t2, scale).iso == '2000-01-01 00:00:00.000'

        # Test unix time.  Values taken from http://en.wikipedia.org/wiki/Unix_time
        t = Time('2013-05-20 21:18:46', scale='utc')
        assert allclose_sec(t.unix, 1369084726.0)
        assert allclose_sec(t.tt.unix, 1369084726.0)

        # Values from issue #1118
        t = Time('2004-09-16T23:59:59', scale='utc')
        assert allclose_sec(t.unix, 1095379199.0)


class TestSofaErrors():
    """Test that erfa status return values are handled correctly"""

    def test_bad_time(self):
        iy = np.array([2000], dtype=np.intc)
        im = np.array([2000], dtype=np.intc)  # bad month
        id = np.array([2000], dtype=np.intc)  # bad day
        with pytest.raises(ValueError):  # bad month, fatal error
            djm0, djm = erfa.cal2jd(iy, im, id)

        iy[0] = -5000
        im[0] = 2
        with pytest.raises(ValueError):  # bad year, fatal error
            djm0, djm = erfa.cal2jd(iy, im, id)

        iy[0] = 2000
        with catch_warnings() as w:
            djm0, djm = erfa.cal2jd(iy, im, id)
        assert len(w) == 1
        assert 'bad day    (JD computed)' in str(w[0].message)

        assert allclose_jd(djm0, [2400000.5])
        assert allclose_jd(djm, [53574.])


class TestCopyReplicate():
    """Test issues related to copying and replicating data"""

    def test_immutable_input(self):
        """Internals are never mutable."""
        jds = np.array([2450000.5], dtype=np.double)
        t = Time(jds, format='jd', scale='tai')
        assert allclose_jd(t.jd, jds)
        jds[0] = 2458654
        assert not allclose_jd(t.jd, jds)

        mjds = np.array([50000.0], dtype=np.double)
        t = Time(mjds, format='mjd', scale='tai')
        assert allclose_jd(t.jd, [2450000.5])
        mjds[0] = 0.0
        assert allclose_jd(t.jd, [2450000.5])

    def test_replicate(self):
        """Test replicate method"""
        t = Time(['2000:001'], format='yday', scale='tai',
                 location=('45d', '45d'))
        t_yday = t.yday
        t_loc_x = t.location.x.copy()
        t2 = t.replicate()
        assert t.yday == t2.yday
        assert t.format == t2.format
        assert t.scale == t2.scale
        assert t.location == t2.location
        # This is not allowed publicly, but here we hack the internal time
        # and location values to show that t and t2 are sharing references.
        t2._time.jd1 += 100.0

        # Need to delete the cached yday attributes (only an issue because
        # of the internal _time hack).
        del t.cache
        del t2.cache

        assert t.yday == t2.yday
        assert t.yday != t_yday  # prove that it changed
        t2_loc_x_view = t2.location.x
        t2_loc_x_view[()] = 0  # use 0 to avoid having to give units
        assert t2.location.x == t2_loc_x_view
        assert t.location.x == t2.location.x
        assert t.location.x != t_loc_x  # prove that it changed

    def test_copy(self):
        """Test copy method"""
        t = Time('2000:001', format='yday', scale='tai',
                 location=('45d', '45d'))
        t_yday = t.yday
        t_loc_x = t.location.x.copy()
        t2 = t.copy()
        assert t.yday == t2.yday
        # This is not allowed publicly, but here we hack the internal time
        # and location values to show that t and t2 are not sharing references.
        t2._time.jd1 += 100.0

        # Need to delete the cached yday attributes (only an issue because
        # of the internal _time hack).
        del t.cache
        del t2.cache

        assert t.yday != t2.yday
        assert t.yday == t_yday  # prove that it did not change
        t2_loc_x_view = t2.location.x
        t2_loc_x_view[()] = 0  # use 0 to avoid having to give units
        assert t2.location.x == t2_loc_x_view
        assert t.location.x != t2.location.x
        assert t.location.x == t_loc_x  # prove that it changed


def test_python_builtin_copy():
    t = Time('2000:001', format='yday', scale='tai')
    t2 = copy.copy(t)
    t3 = copy.deepcopy(t)

    assert t.jd == t2.jd
    assert t.jd == t3.jd


def test_now():
    """
    Tests creating a Time object with the `now` class method.
    """

    now = datetime.datetime.utcnow()
    t = Time.now()

    assert t.format == 'datetime'
    assert t.scale == 'utc'

    dt = t.datetime - now  # a datetime.timedelta object

    # this gives a .1 second margin between the `utcnow` call and the `Time`
    # initializer, which is really way more generous than necessary - typical
    # times are more like microseconds.  But it seems safer in case some
    # platforms have slow clock calls or something.

    assert dt.total_seconds() < 0.1


def test_decimalyear():
    t = Time('2001:001', format='yday')
    assert t.decimalyear == 2001.0

    t = Time(2000.0, [0.5, 0.75], format='decimalyear')
    assert np.all(t.value == [2000.5, 2000.75])

    jd0 = Time('2000:001').jd
    jd1 = Time('2001:001').jd
    d_jd = jd1 - jd0
    assert np.all(t.jd == [jd0 + 0.5 * d_jd,
                           jd0 + 0.75 * d_jd])


def test_fits_year0():
    t = Time(1721425.5, format='jd')
    assert t.fits == '0001-01-01T00:00:00.000'
    t = Time(1721425.5 - 366., format='jd')
    assert t.fits == '+00000-01-01T00:00:00.000'
    t = Time(1721425.5 - 366. - 365., format='jd')
    assert t.fits == '-00001-01-01T00:00:00.000'


def test_fits_year10000():
    t = Time(5373484.5, format='jd', scale='tai')
    assert t.fits == '+10000-01-01T00:00:00.000'
    t = Time(5373484.5 - 365., format='jd', scale='tai')
    assert t.fits == '9999-01-01T00:00:00.000'
    t = Time(5373484.5, -1./24./3600., format='jd', scale='tai')
    assert t.fits == '9999-12-31T23:59:59.000'


def test_dir():
    t = Time('2000:001', format='yday', scale='tai')
    assert 'utc' in dir(t)


def test_bool():
    """Any Time object should evaluate to True unless it is empty [#3520]."""
    t = Time(np.arange(50000, 50010), format='mjd', scale='utc')
    assert bool(t) is True
    assert bool(t[0]) is True
    assert bool(t[:0]) is False


def test_len_size():
    """Check length of Time objects and that scalar ones do not have one."""
    t = Time(np.arange(50000, 50010), format='mjd', scale='utc')
    assert len(t) == 10 and t.size == 10
    t1 = Time(np.arange(50000, 50010).reshape(2, 5), format='mjd', scale='utc')
    assert len(t1) == 2 and t1.size == 10
    # Can have length 1 or length 0 arrays.
    t2 = t[:1]
    assert len(t2) == 1 and t2.size == 1
    t3 = t[:0]
    assert len(t3) == 0 and t3.size == 0
    # But cannot get length from scalar.
    t4 = t[0]
    with pytest.raises(TypeError) as err:
        len(t4)
    # Ensure we're not just getting the old error of
    # "object of type 'float' has no len()".
    assert 'Time' in str(err)


def test_TimeFormat_scale():
    """guard against recurrence of #1122, where TimeFormat class looses uses
    attributes (delta_ut1_utc here), preventing conversion to unix, cxc"""
    t = Time('1900-01-01', scale='ut1')
    t.delta_ut1_utc = 0.0
    t.unix
    assert t.unix == t.utc.unix


@pytest.mark.remote_data
def test_scale_conversion():
    Time(Time.now().cxcsec, format='cxcsec', scale='ut1')


def test_byteorder():
    """Ensure that bigendian and little-endian both work (closes #2942)"""
    mjd = np.array([53000.00, 54000.00])
    big_endian = mjd.astype('>f8')
    little_endian = mjd.astype('<f8')
    time_mjd = Time(mjd, format='mjd')
    time_big = Time(big_endian, format='mjd')
    time_little = Time(little_endian, format='mjd')
    assert np.all(time_big == time_mjd)
    assert np.all(time_little == time_mjd)


def test_datetime_tzinfo():
    """
    Test #3160 that time zone info in datetime objects is respected.
    """
    class TZm6(datetime.tzinfo):
        def utcoffset(self, dt):
            return datetime.timedelta(hours=-6)

    d = datetime.datetime(2002, 1, 2, 10, 3, 4, tzinfo=TZm6())
    t = Time(d)
    assert t.value == datetime.datetime(2002, 1, 2, 16, 3, 4)


def test_subfmts_regex():
    """
    Test having a custom subfmts with a regular expression
    """
    class TimeLongYear(TimeString):
        name = 'longyear'
        subfmts = (('date',
                    r'(?P<year>[+-]\d{5})-%m-%d',  # hybrid
                    '{year:+06d}-{mon:02d}-{day:02d}'),)
    t = Time('+02000-02-03', format='longyear')
    assert t.value == '+02000-02-03'
    assert t.jd == Time('2000-02-03').jd


def test_set_format_basic():
    """
    Test basics of setting format attribute.
    """
    for format, value in (('jd', 2451577.5),
                          ('mjd', 51577.0),
                          ('cxcsec', 65923264.184),  # confirmed with Chandra.Time
                          ('datetime', datetime.datetime(2000, 2, 3, 0, 0)),
                          ('iso', '2000-02-03 00:00:00.000')):
        t = Time('+02000-02-03', format='fits')
        t0 = t.replicate()
        t.format = format
        assert t.value == value
        # Internal jd1 and jd2 are preserved
        assert t._time.jd1 is t0._time.jd1
        assert t._time.jd2 is t0._time.jd2


def test_set_format_shares_subfmt():
    """
    Set format and round trip through a format that shares out_subfmt
    """
    t = Time('+02000-02-03', format='fits', out_subfmt='date_hms', precision=5)
    tc = t.copy()

    t.format = 'isot'
    assert t.precision == 5
    assert t.out_subfmt == 'date_hms'
    assert t.value == '2000-02-03T00:00:00.00000'

    t.format = 'fits'
    assert t.value == tc.value
    assert t.precision == 5


def test_set_format_does_not_share_subfmt():
    """
    Set format and round trip through a format that does not share out_subfmt
    """
    t = Time('+02000-02-03', format='fits', out_subfmt='longdate')

    t.format = 'isot'
    assert t.out_subfmt == '*'  # longdate_hms not there, goes to default
    assert t.value == '2000-02-03T00:00:00.000'

    t.format = 'fits'
    assert t.out_subfmt == '*'
    assert t.value == '2000-02-03T00:00:00.000'  # date_hms


def test_replicate_value_error():
    """
    Passing a bad format to replicate should raise ValueError, not KeyError.
    PR #3857.
    """
    t1 = Time('2007:001', scale='tai')
    with pytest.raises(ValueError) as err:
        t1.replicate(format='definitely_not_a_valid_format')
    assert 'format must be one of' in str(err)


def test_remove_astropy_time():
    """
    Make sure that 'astropy_time' format is really gone after #3857.  Kind of
    silly test but just to be sure.
    """
    t1 = Time('2007:001', scale='tai')
    assert 'astropy_time' not in t1.FORMATS
    with pytest.raises(ValueError) as err:
        Time(t1, format='astropy_time')
    assert 'format must be one of' in str(err)


def test_isiterable():
    """
    Ensure that scalar `Time` instances are not reported as iterable by the
    `isiterable` utility.

    Regression test for https://github.com/astropy/astropy/issues/4048
    """

    t1 = Time.now()
    assert not isiterable(t1)

    t2 = Time(['1999-01-01 00:00:00.123456789', '2010-01-01 00:00:00'],
              format='iso', scale='utc')
    assert isiterable(t2)


def test_to_datetime():
    tz = TimezoneInfo(utc_offset=-10*u.hour, tzname='US/Hawaii')
    # The above lines produces a `datetime.tzinfo` object similar to:
    #     tzinfo = pytz.timezone('US/Hawaii')
    time = Time('2010-09-03 00:00:00')
    tz_aware_datetime = time.to_datetime(tz)
    assert tz_aware_datetime.time() == datetime.time(14, 0)
    forced_to_astropy_time = Time(tz_aware_datetime)
    assert tz.tzname(time.datetime) == tz_aware_datetime.tzname()
    assert time == forced_to_astropy_time

    # Test non-scalar time inputs:
    time = Time(['2010-09-03 00:00:00', '2005-09-03 06:00:00',
                 '1990-09-03 06:00:00'])
    tz_aware_datetime = time.to_datetime(tz)
    forced_to_astropy_time = Time(tz_aware_datetime)
    for dt, tz_dt in zip(time.datetime, tz_aware_datetime):
        assert tz.tzname(dt) == tz_dt.tzname()
    assert np.all(time == forced_to_astropy_time)

    with pytest.raises(ValueError) as e:
        Time('2015-06-30 23:59:60.000').to_datetime()
        assert 'does not support leap seconds' in str(e.message)


@pytest.mark.skipif('not HAS_PYTZ')
def test_to_datetime_pytz():

    tz = pytz.timezone('US/Hawaii')
    time = Time('2010-09-03 00:00:00')
    tz_aware_datetime = time.to_datetime(tz)
    forced_to_astropy_time = Time(tz_aware_datetime)
    assert tz_aware_datetime.time() == datetime.time(14, 0)
    assert tz.tzname(time.datetime) == tz_aware_datetime.tzname()
    assert time == forced_to_astropy_time

    # Test non-scalar time inputs:
    time = Time(['2010-09-03 00:00:00', '2005-09-03 06:00:00',
                 '1990-09-03 06:00:00'])
    tz_aware_datetime = time.to_datetime(tz)
    forced_to_astropy_time = Time(tz_aware_datetime)
    for dt, tz_dt in zip(time.datetime, tz_aware_datetime):
        assert tz.tzname(dt) == tz_dt.tzname()
    assert np.all(time == forced_to_astropy_time)


def test_cache():
    t = Time('2010-09-03 00:00:00')
    t2 = Time('2010-09-03 00:00:00')

    # Time starts out without a cache
    assert 'cache' not in t._time.__dict__

    # Access the iso format and confirm that the cached version is as expected
    t.iso
    assert t.cache['format']['iso'] == t2.iso

    # Access the TAI scale and confirm that the cached version is as expected
    t.tai
    assert t.cache['scale']['tai'] == t2.tai

    # New Time object after scale transform does not have a cache yet
    assert 'cache' not in t.tt._time.__dict__

    # Clear the cache
    del t.cache
    assert 'cache' not in t._time.__dict__
    # Check accessing the cache creates an empty dictionary
    assert not t.cache
    assert 'cache' in t._time.__dict__


def test_epoch_date_jd_is_day_fraction():
    """
    Ensure that jd1 and jd2 of an epoch Time are respect the (day, fraction) convention
    (see #6638)
    """
    t0 = Time("J2000", scale="tdb")

    assert t0.jd1 == 2451545.0
    assert t0.jd2 == 0.0

    t1 = Time(datetime.datetime(2000, 1, 1, 12, 0, 0), scale="tdb")

    assert t1.jd1 == 2451545.0
    assert t1.jd2 == 0.0


def test_sum_is_equivalent():
    """
    Ensure that two equal dates defined in different ways behave equally (#6638)
    """
    t0 = Time("J2000", scale="tdb")
    t1 = Time("2000-01-01 12:00:00", scale="tdb")

    assert t0 == t1
    assert (t0 + 1 * u.second) == (t1 + 1 * u.second)


def test_string_valued_columns():
    # Columns have a nice shim that translates bytes to string as needed.
    # Ensure Time can handle these.  Use multi-d array just to be sure.
    times = [[['{:04d}-{:02d}-{:02d}'.format(y, m, d) for d in range(1, 3)]
              for m in range(5, 7)] for y in range(2012, 2014)]
    cutf32 = Column(times)
    cbytes = cutf32.astype('S')
    tutf32 = Time(cutf32)
    tbytes = Time(cbytes)
    assert np.all(tutf32 == tbytes)
    tutf32 = Time(Column(['B1950']))
    tbytes = Time(Column([b'B1950']))
    assert tutf32 == tbytes
    # Regression tests for arrays with entries with unequal length. gh-6903.
    times = Column([b'2012-01-01', b'2012-01-01T00:00:00'])
    assert np.all(Time(times) == Time(['2012-01-01', '2012-01-01T00:00:00']))


def test_bytes_input():
    tstring = '2011-01-02T03:04:05'
    tbytes = b'2011-01-02T03:04:05'
    assert tbytes.decode('ascii') == tstring
    t0 = Time(tstring)
    t1 = Time(tbytes)
    assert t1 == t0
    tarray = np.array(tbytes)
    assert tarray.dtype.kind == 'S'
    t2 = Time(tarray)
    assert t2 == t0


def test_writeable_flag():
    t = Time([1, 2, 3], format='cxcsec')
    t[1] = 5.0
    assert allclose_sec(t[1].value, 5.0)

    t.writeable = False
    with pytest.raises(ValueError) as err:
        t[1] = 5.0
    assert 'Time object is read-only. Make a copy()' in str(err)

    with pytest.raises(ValueError) as err:
        t[:] = 5.0
    assert 'Time object is read-only. Make a copy()' in str(err)

    t.writeable = True
    t[1] = 10.0
    assert allclose_sec(t[1].value, 10.0)

    # Scalar is not writeable
    t = Time('2000:001', scale='utc')
    with pytest.raises(ValueError) as err:
        t[()] = '2000:002'
    assert 'scalar Time object is read-only.' in str(err)

    # Transformed attribute is not writeable
    t = Time(['2000:001', '2000:002'], scale='utc')
    t2 = t.tt  # t2 is read-only now because t.tt is cached
    with pytest.raises(ValueError) as err:
        t2[0] = '2005:001'
    assert 'Time object is read-only. Make a copy()' in str(err)


def test_setitem_location():
    loc = EarthLocation(x=[1, 2] * u.m, y=[3, 4] * u.m, z=[5, 6] * u.m)
    t = Time([[1, 2], [3, 4]], format='cxcsec', location=loc)

    # Succeeds because the right hand side makes no implication about
    # location and just inherits t.location
    t[0, 0] = 0
    assert allclose_sec(t.value, [[0, 2], [3, 4]])

    # Fails because the right hand side has location=None
    with pytest.raises(ValueError) as err:
        t[0, 0] = Time(-1, format='cxcsec')
    assert ('cannot set to Time with different location: '
            'expected location={} and '
            'got location=None'.format(loc[0])) in str(err)

    # Succeeds because the right hand side correctly sets location
    t[0, 0] = Time(-2, format='cxcsec', location=loc[0])
    assert allclose_sec(t.value, [[-2, 2], [3, 4]])

    # Fails because the right hand side has different location
    with pytest.raises(ValueError) as err:
        t[0, 0] = Time(-2, format='cxcsec', location=loc[1])
    assert ('cannot set to Time with different location: '
            'expected location={} and '
            'got location={}'.format(loc[0], loc[1])) in str(err)

    # Fails because the Time has None location and RHS has defined location
    t = Time([[1, 2], [3, 4]], format='cxcsec')
    with pytest.raises(ValueError) as err:
        t[0, 0] = Time(-2, format='cxcsec', location=loc[1])
    assert ('cannot set to Time with different location: '
            'expected location=None and '
            'got location={}'.format(loc[1])) in str(err)

    # Broadcasting works
    t = Time([[1, 2], [3, 4]], format='cxcsec', location=loc)
    t[0, :] = Time([-3, -4], format='cxcsec', location=loc)
    assert allclose_sec(t.value, [[-3, -4], [3, 4]])


def test_setitem_from_python_objects():
    t = Time([[1, 2], [3, 4]], format='cxcsec')
    assert t.cache == {}
    t.iso
    assert 'iso' in t.cache['format']
    assert np.all(t.iso == [['1998-01-01 00:00:01.000', '1998-01-01 00:00:02.000'],
                            ['1998-01-01 00:00:03.000', '1998-01-01 00:00:04.000']])

    # Setting item clears cache
    t[0, 1] = 100
    assert t.cache == {}
    assert allclose_sec(t.value, [[1, 100],
                                  [3, 4]])
    assert np.all(t.iso == [['1998-01-01 00:00:01.000', '1998-01-01 00:01:40.000'],
                            ['1998-01-01 00:00:03.000', '1998-01-01 00:00:04.000']])

    # Set with a float value
    t.iso
    t[1, :] = 200
    assert t.cache == {}
    assert allclose_sec(t.value, [[1, 100],
                                  [200, 200]])

    # Array of strings in yday format
    t[:, 1] = ['1998:002', '1998:003']
    assert allclose_sec(t.value, [[1, 86400 * 1],
                                  [200, 86400 * 2]])

    # Incompatible numeric value
    t = Time(['2000:001', '2000:002'])
    t[0] = '2001:001'
    with pytest.raises(ValueError) as err:
        t[0] = 100
    assert 'cannot convert value to a compatible Time object' in str(err)


def test_setitem_from_time_objects():
    """Set from existing Time object.
    """
    # Set from time object with different scale
    t = Time(['2000:001', '2000:002'], scale='utc')
    t2 = Time(['2000:010'], scale='tai')
    t[1] = t2[0]
    assert t.value[1] == t2.utc.value[0]

    # Time object with different scale and format
    t = Time(['2000:001', '2000:002'], scale='utc')
    t2.format = 'jyear'
    t[1] = t2[0]
    assert t.yday[1] == t2.utc.yday[0]


def test_setitem_bad_item():
    t = Time([1, 2], format='cxcsec')
    with pytest.raises(IndexError):
        t['asdf'] = 3


def test_setitem_deltas():
    """Setting invalidates any transform deltas"""
    t = Time([1, 2], format='cxcsec')
    t.delta_tdb_tt = [1, 2]
    t.delta_ut1_utc = [3, 4]
    t[1] = 3
    assert not hasattr(t, '_delta_tdb_tt')
    assert not hasattr(t, '_delta_ut1_utc')


def test_subclass():
    """Check that we can initialize subclasses with a Time instance."""
    # Ref: Issue gh-#7449 and PR gh-#7453.

    class _Time(Time):
        pass

    t1 = Time('1999-01-01T01:01:01')
    t2 = _Time(t1)

    assert t2.__class__ == _Time
    assert t1 == t2


def test_strftime_scalar():
    """Test of Time.strftime
    """
    time_string = '2010-09-03 06:00:00'
    t = Time(time_string)

    for format in t.FORMATS:
        t.format = format
        assert t.strftime('%Y-%m-%d %H:%M:%S') == time_string


def test_strftime_array():
    tstrings = ['2010-09-03 00:00:00', '2005-09-03 06:00:00',
                '1995-12-31 23:59:60']
    t = Time(tstrings)

    for format in t.FORMATS:
        t.format = format
        assert t.strftime('%Y-%m-%d %H:%M:%S').tolist() == tstrings


def test_strftime_array_2():
    tstrings = [['1998-01-01 00:00:01', '1998-01-01 00:00:02'],
                ['1998-01-01 00:00:03', '1995-12-31 23:59:60']]
    tstrings = np.array(tstrings)

    t = Time(tstrings)

    for format in t.FORMATS:
        t.format = format
        assert np.all(t.strftime('%Y-%m-%d %H:%M:%S') == tstrings)
        assert t.strftime('%Y-%m-%d %H:%M:%S').shape == tstrings.shape


def test_strftime_leapsecond():
    time_string = '1995-12-31 23:59:60'
    t = Time(time_string)

    for format in t.FORMATS:
        t.format = format
        assert t.strftime('%Y-%m-%d %H:%M:%S') == time_string


def test_strptime_scalar():
    """Test of Time.strptime
    """
    time_string = '2007-May-04 21:08:12'
    time_object = Time('2007-05-04 21:08:12')
    t = Time.strptime(time_string, '%Y-%b-%d %H:%M:%S')

    assert t == time_object


def test_strptime_array():
    """Test of Time.strptime
    """
    tstrings = [['1998-Jan-01 00:00:01', '1998-Jan-01 00:00:02'],
                ['1998-Jan-01 00:00:03', '1998-Jan-01 00:00:04']]
    tstrings = np.array(tstrings)

    time_object = Time([['1998-01-01 00:00:01', '1998-01-01 00:00:02'],
                        ['1998-01-01 00:00:03', '1998-01-01 00:00:04']])
    t = Time.strptime(tstrings, '%Y-%b-%d %H:%M:%S')

    assert np.all(t == time_object)
    assert t.shape == tstrings.shape


def test_strptime_badinput():
    tstrings = [1, 2, 3]
    with pytest.raises(TypeError):
        Time.strptime(tstrings, '%S')


def test_strptime_input_bytes_scalar():
    time_string = b'2007-May-04 21:08:12'
    time_object = Time('2007-05-04 21:08:12')
    t = Time.strptime(time_string, '%Y-%b-%d %H:%M:%S')

    assert t == time_object


def test_strptime_input_bytes_array():
    tstrings = [[b'1998-Jan-01 00:00:01', b'1998-Jan-01 00:00:02'],
                [b'1998-Jan-01 00:00:03', b'1998-Jan-01 00:00:04']]
    tstrings = np.array(tstrings)

    time_object = Time([['1998-01-01 00:00:01', '1998-01-01 00:00:02'],
                        ['1998-01-01 00:00:03', '1998-01-01 00:00:04']])
    t = Time.strptime(tstrings, '%Y-%b-%d %H:%M:%S')

    assert np.all(t == time_object)
    assert t.shape == tstrings.shape


def test_strptime_leapsecond():
    time_obj1 = Time('1995-12-31T23:59:60', format='isot')
    time_obj2 = Time.strptime('1995-Dec-31 23:59:60', '%Y-%b-%d %H:%M:%S')

    assert time_obj1 == time_obj2


def test_strptime_3_digit_year():
    time_obj1 = Time('0995-12-31T00:00:00', format='isot')
    time_obj2 = Time.strptime('0995-Dec-31 00:00:00', '%Y-%b-%d %H:%M:%S')

    assert time_obj1 == time_obj2


def test_strptime_fracsec_scalar():
    time_string = '2007-May-04 21:08:12.123'
    time_object = Time('2007-05-04 21:08:12.123')
    t = Time.strptime(time_string, '%Y-%b-%d %H:%M:%S.%f')

    assert t == time_object


def test_strptime_fracsec_array():
    """Test of Time.strptime
    """
    tstrings = [['1998-Jan-01 00:00:01.123', '1998-Jan-01 00:00:02.000001'],
                ['1998-Jan-01 00:00:03.000900', '1998-Jan-01 00:00:04.123456']]
    tstrings = np.array(tstrings)

    time_object = Time([['1998-01-01 00:00:01.123', '1998-01-01 00:00:02.000001'],
                        ['1998-01-01 00:00:03.000900', '1998-01-01 00:00:04.123456']])
    t = Time.strptime(tstrings, '%Y-%b-%d %H:%M:%S.%f')

    assert np.all(t == time_object)
    assert t.shape == tstrings.shape


def test_strftime_scalar_fracsec():
    """Test of Time.strftime
    """
    time_string = '2010-09-03 06:00:00.123'
    t = Time(time_string)

    for format in t.FORMATS:
        t.format = format
        assert t.strftime('%Y-%m-%d %H:%M:%S.%f') == time_string


def test_strftime_scalar_fracsec_precision():
    time_string = '2010-09-03 06:00:00.123123123'
    t = Time(time_string)
    assert t.strftime('%Y-%m-%d %H:%M:%S.%f') == '2010-09-03 06:00:00.123'
    t.precision = 9
    assert t.strftime('%Y-%m-%d %H:%M:%S.%f') == '2010-09-03 06:00:00.123123123'


def test_strftime_array_fracsec():
    tstrings = ['2010-09-03 00:00:00.123000', '2005-09-03 06:00:00.000001',
                '1995-12-31 23:59:60.000900']
    t = Time(tstrings)
    t.precision = 6

    for format in t.FORMATS:
        t.format = format
        assert t.strftime('%Y-%m-%d %H:%M:%S.%f').tolist() == tstrings


def test_insert_time():
    tm = Time([1, 2], format='unix')

    # Insert a scalar using an auto-parsed string
    tm2 = tm.insert(1, '1970-01-01 00:01:00')
    assert np.all(tm2 == Time([1, 60, 2], format='unix'))

    # Insert scalar using a Time value
    tm2 = tm.insert(1, Time('1970-01-01 00:01:00'))
    assert np.all(tm2 == Time([1, 60, 2], format='unix'))

    # Insert length=1 array with a Time value
    tm2 = tm.insert(1, [Time('1970-01-01 00:01:00')])
    assert np.all(tm2 == Time([1, 60, 2], format='unix'))

    # Insert length=2 list with float values matching unix format.
    # Also actually provide axis=0 unlike all other tests.
    tm2 = tm.insert(1, [10, 20], axis=0)
    assert np.all(tm2 == Time([1, 10, 20, 2], format='unix'))

    # Insert length=2 np.array with float values matching unix format
    tm2 = tm.insert(1, np.array([10, 20]))
    assert np.all(tm2 == Time([1, 10, 20, 2], format='unix'))

    # Insert length=2 np.array with float values at the end
    tm2 = tm.insert(2, np.array([10, 20]))
    assert np.all(tm2 == Time([1, 2, 10, 20], format='unix'))

    # Insert length=2 np.array with float values at the beginning
    # with a negative index
    tm2 = tm.insert(-2, np.array([10, 20]))
    assert np.all(tm2 == Time([10, 20, 1, 2], format='unix'))


def test_insert_exceptions():
    tm = Time(1, format='unix')
    with pytest.raises(TypeError) as err:
        tm.insert(0, 50)
    assert 'cannot insert into scalar' in str(err)

    tm = Time([1, 2], format='unix')
    with pytest.raises(ValueError) as err:
        tm.insert(0, 50, axis=1)
    assert 'axis must be 0' in str(err)

    with pytest.raises(TypeError) as err:
        tm.insert(slice(None), 50)
    assert 'obj arg must be an integer' in str(err)

    with pytest.raises(IndexError) as err:
        tm.insert(-100, 50)
    assert 'index -100 is out of bounds for axis 0 with size 2' in str(err)


def test_datetime64_no_format():
    dt64 = np.datetime64('2000-01-02T03:04:05.123456789')
    t = Time(dt64, scale='utc', precision=9)
    assert t.iso == '2000-01-02 03:04:05.123456789'
    assert t.datetime64 == dt64
    assert t.value == dt64