construct a pvsyst_system object in single axis tracker test to ensure the consistency with PVsyst results.

move the comment line up to reduce the line length

Author: mayudong

pvlib/test/test_tracking.py

@@ -199,13 +199,14 @@ def test_SingleAxisTracker_tracking():
     pvsyst_solar_height = 27.315
     pvsyst_axis_tilt = 20.
     pvsyst_axis_azimuth = 20.
-    system.backtrack = False
-    system.max_angle = 60.
-    system.axis_tilt = pvsyst_axis_tilt
-    system.axis_azimuth = 180+pvsyst_axis_azimuth
-    apparent_azimuth = pd.Series([180+pvsyst_solar_azimuth]) # the definition of azimuth is different from PYsyst
+    pvsyst_system = tracking.SingleAxisTracker(max_angle=60.,
+                                               axis_tilt=pvsyst_axis_tilt,
+                                               axis_azimuth=180+pvsyst_axis_azimuth,
+                                               backtrack=False)
+    # the definition of azimuth is different from PYsyst
+    apparent_azimuth = pd.Series([180+pvsyst_solar_azimuth])
     apparent_zenith = pd.Series([90-pvsyst_solar_height])
-    tracker_data = system.singleaxis(apparent_zenith, apparent_azimuth)
+    tracker_data = pvsyst_system.singleaxis(apparent_zenith, apparent_azimuth)
     expect = pd.DataFrame({'aoi': 41.07852 , 'surface_azimuth': 180-18.432 ,
                            'surface_tilt': 24.92122 , 'tracker_theta': -15.18391},
                            index=[0], dtype=np.float64)