add disc test

pvlib/test/test_clearsky.py

@@ -8,6 +8,8 @@
 
 from nose.tools import raises
 
+from numpy.testing import assert_almost_equal
+
 from pvlib.location import Location
 from pvlib import clearsky
 from pvlib import solarposition
@@ -54,3 +56,23 @@ def test_haurwitz():
 def test_haurwitz_keys():
     clearsky_data = clearsky.haurwitz(ephem_data['zenith'])
     assert 'GHI' in clearsky_data.columns
+
+
+# test DISC
+def test_disc_keys():
+    clearsky_data = clearsky.ineichen(times, tus)
+    disc_data = clearsky.disc(clearsky_data['GHI'], ephem_data['zenith'], 
+                              ephem_data.index)
+    assert 'DNI_gen_DISC' in disc_data.columns
+    assert 'Kt_gen_DISC' in disc_data.columns
+    assert 'AM' in disc_data.columns
+
+def test_disc_value():
+    times = pd.DatetimeIndex(['2014-06-24T12-0700','2014-06-24T18-0700'])
+    ghi = pd.Series([1038.62, 254.53], index=times)
+    zenith = pd.Series([10.567, 72.469], index=times)
+    pressure = 93193.
+    disc_data = clearsky.disc(ghi, zenith, times, pressure=pressure)
+    assert_almost_equal(disc_data['DNI_gen_DISC'].values,
+                        np.array([830.46, 676.09]), 1)
+