new_contents: import logging
  pvl_logger = logging.getLogger('pvlib')
  
  import datetime
  
  import numpy as np
  import pandas as pd
  
  from nose.tools import raises, assert_almost_equals
  from pandas.util.testing import assert_frame_equal
  
  from ..location import Location
  from .. import solarposition
  
  
  # setup times and locations to be tested.
  times = pd.date_range(start=datetime.datetime(2014,6,24), 
                        end=datetime.datetime(2014,6,26), freq='15Min')
  
  tus = Location(32.2, -111, 'US/Arizona', 700) # no DST issues possible
  golden_mst = Location(39.742476, -105.1786, 'MST', 1830.14) # no DST issues possible
  golden = Location(39.742476, -105.1786, 'America/Denver', 1830.14) # DST issues possible
  
  times_localized = times.tz_localize(tus.tz)
  
  # the physical tests are run at the same time as the NREL SPA test.
  # pyephem reproduces the NREL result to 2 decimal places.
  # this doesn't mean that one code is better than the other. 
  
  
  def test_spa_physical():
      times = pd.date_range(datetime.datetime(2003,10,17,12,30,30), periods=1, freq='D')
      ephem_data = solarposition.spa(times, golden_mst).ix[0]
      
      assert_almost_equals(50.111622, ephem_data['zenith'], 6)
      assert_almost_equals(194.340241, ephem_data['azimuth'], 6)
      assert_almost_equals(39.888378, ephem_data['elevation'], 6)
      
      
      
  def test_spa_physical_dst():
      times = pd.date_range(datetime.datetime(2003,10,17,13,30,30), periods=1, freq='D')
      ephem_data = solarposition.spa(times, golden).ix[0]
      
      assert_almost_equals(50.111622, ephem_data['zenith'], 6)
      assert_almost_equals(194.340241, ephem_data['azimuth'], 6)
      assert_almost_equals(39.888378, ephem_data['elevation'], 6)
  
  
  
  def test_spa_localization():    
      assert_frame_equal(solarposition.spa(times, tus), solarposition.spa(times_localized, tus))
  
  
  
  def test_pyephem_physical():
      times = pd.date_range(datetime.datetime(2003,10,17,12,30,30), periods=1, freq='D')
      ephem_data = solarposition.pyephem(times, golden_mst, pressure=82000, temperature=11).ix[0]
      
      assert_almost_equals(50.111622, ephem_data['apparent_zenith'], 2)
      assert_almost_equals(194.340241, ephem_data['apparent_azimuth'], 2)
      assert_almost_equals(39.888378, ephem_data['apparent_elevation'], 2)
      
  
  
  def test_pyephem_physical_dst():
      times = pd.date_range(datetime.datetime(2003,10,17,13,30,30), periods=1, freq='D')
      ephem_data = solarposition.pyephem(times, golden, pressure=82000, temperature=11).ix[0]
      
      assert_almost_equals(50.111622, ephem_data['apparent_zenith'], 2)
      assert_almost_equals(194.340241, ephem_data['apparent_azimuth'], 2)
      assert_almost_equals(39.888378, ephem_data['apparent_elevation'], 2)
  
  
  
  def test_pyephem_localization():  
      assert_frame_equal(solarposition.pyephem(times, tus), solarposition.pyephem(times_localized, tus))
  
          
          
  # add tests for daylight savings time?
subject: add solpos test suite