add explicit tests for aoi and aoi projection functions (#345)

* add explicit tests for aoi and aoi projection functions

* make expected values consistent with atol specification

Author: wholmgren

docs/sphinx/source/whatsnew/v0.4.6.rst

@@ -24,6 +24,12 @@ Documentation
 ~~~~~~~~~~~~~
 
 
+Testing
+~~~~~~~
+
+* Added explicit tests for aoi and aoi_projection functions.
+
+
 Contributors
 ~~~~~~~~~~~~
 

pvlib/test/test_irradiance.py

@@ -422,3 +422,22 @@ def test_dni():
     assert_series_equal(dni,
                         pd.Series([float('nan'), float('nan'), 573.685662283,
                                    146.190220008, 573.685662283]))
+
+
+@pytest.mark.parametrize(
+    'surface_tilt,surface_azimuth,solar_zenith,solar_azimuth,aoi_expected,aoi_proj_expected', [
+    (0, 0, 0, 0, 0, 1),
+    (30, 180, 30, 180, 0, 1),
+    (30, 180, 150, 0, 180, -1),
+    (90, 0, 30, 60, 75.5224878, 0.25),
+    (90, 0, 30, 170, 119.4987042, -0.4924038)])
+def test_aoi_and_aoi_projection(surface_tilt, surface_azimuth, solar_zenith,
+                                solar_azimuth,  aoi_expected,
+                                aoi_proj_expected):
+    aoi = irradiance.aoi(surface_tilt, surface_azimuth, solar_zenith,
+                         solar_azimuth)
+    assert_allclose(aoi, aoi_expected, atol=1e-6)
+
+    aoi_projection = irradiance.aoi_projection(
+        surface_tilt, surface_azimuth, solar_zenith, solar_azimuth)
+    assert_allclose(aoi_projection, aoi_proj_expected, atol=1e-6)