'Check time arithmetic as well as properly keeping track of whether
a time is a scalar or a vector'

def test_add_vector(self):

    t = Time(0.0, format='mjd', scale='utc')
    t2 = Time([0.0, 1.0], format='mjd', scale='utc')
    dt = TimeDelta(100.0, format='jd')
    dt2 = TimeDelta([100.0, 200.0], format='jd')
    out = (t + dt)
    assert allclose_jd(out.mjd, 100.0)
    assert out.isscalar
    out = (t + dt2)
    assert allclose_jd(out.mjd, [100.0, 200.0])
    assert (not out.isscalar)
    out = (t2 + dt)
    assert allclose_jd(out.mjd, [100.0, 101.0])
    assert (not out.isscalar)
    out = (dt + dt)
    assert allclose_jd(out.jd, 200.0)
    assert out.isscalar
    out = (dt + dt2)
    assert allclose_jd(out.jd, [200.0, 300.0])
    assert (not out.isscalar)
    out = (dt + t)
    assert allclose_jd(out.mjd, 100.0)
    assert out.isscalar
    out = (dt2 + t)
    assert allclose_jd(out.mjd, [100.0, 200.0])
    assert (not out.isscalar)
    out = (dt + t2)
    assert allclose_jd(out.mjd, [100.0, 101.0])
    assert (not out.isscalar)
    out = (dt2 + dt)
    assert allclose_jd(out.jd, [200.0, 300.0])
    assert (not out.isscalar)
