fix dict update, a couple of tests

Author: wholmgren

pvlib/modelchain.py

@@ -34,7 +34,7 @@
 )
 # update when full pvsyst models are known
 PVSYST_CONFIG = dict(
-    dc_model='pvsyst'
+    dc_model='pvsyst', spectral_model='no_loss'
 )
 
 
@@ -411,8 +411,9 @@ def with_pvwatts(cls, system, location,
             Name of ModelChain instance.
 
         **kwargs
-            Arbitrary keyword arguments. Included for compatibility, but not
-            used.
+            Parameters supplied here are passed to the ModelChain
+            constructor and take precedence over the default
+            configuration.
 
         Examples
         --------
@@ -437,16 +438,16 @@ def with_pvwatts(cls, system, location,
           temperature_model: sapm_temp
           losses_model: pvwatts_losses
         """
-
-        kwargs.update(PVWATTS_CONFIG)
+        config = PVWATTS_CONFIG.copy()
+        config.update(kwargs)
         return ModelChain(
             system, location,
             orientation_strategy=orientation_strategy,
             clearsky_model=clearsky_model,
             airmass_model=airmass_model,
             temperature_model=temperature_model,
             name=name,
-            **kwargs
+            **config
         )
 
     @classmethod
@@ -494,8 +495,9 @@ def with_sapm(cls, system, location,
             Name of ModelChain instance.
 
         **kwargs
-            Arbitrary keyword arguments. Included for compatibility, but not
-            used.
+            Parameters supplied here are passed to the ModelChain
+            constructor and take precedence over the default
+            configuration.
 
         Examples
         --------
@@ -522,8 +524,8 @@ def with_sapm(cls, system, location,
           temperature_model: sapm_temp
           losses_model: no_extra_losses
         """
-
-        kwargs.update(SAPM_CONFIG)
+        config = SAPM_CONFIG.copy()
+        config.update(kwargs)
         return ModelChain(
             system, location,
             orientation_strategy=orientation_strategy,
@@ -532,7 +534,7 @@ def with_sapm(cls, system, location,
             solar_position_method=solar_position_method,
             airmass_model=airmass_model,
             name=name,
-            **kwargs
+            **config
         )
 
     # update when full pvsyst models are known
@@ -581,8 +583,9 @@ def with_pvsyst(cls, system, location,
             Name of ModelChain instance.
 
         **kwargs
-            Arbitrary keyword arguments. Included for compatibility, but not
-            used.
+            Parameters supplied here are passed to the ModelChain
+            constructor and take precedence over the default
+            configuration.
 
         Examples
         --------
@@ -609,8 +612,8 @@ def with_pvsyst(cls, system, location,
           temperature_model: sapm_temp
           losses_model: no_extra_losses
         """
-
-        kwargs.update(PVSYST_CONFIG)
+        config = PVSYST_CONFIG.copy()
+        config.update(kwargs)
         return ModelChain(
             system, location,
             orientation_strategy=orientation_strategy,
@@ -619,7 +622,7 @@ def with_pvsyst(cls, system, location,
             solar_position_method=solar_position_method,
             airmass_model=airmass_model,
             name=name,
-            **kwargs
+            **config
         )
 
     def __repr__(self):

pvlib/tests/test_modelchain.py

@@ -170,6 +170,21 @@ def test_ModelChain_creation(sapm_dc_snl_ac_system, location):
     ModelChain(sapm_dc_snl_ac_system, location)
 
 
+def test_with_pvsyst(pvsyst_dc_snl_ac_system, location):
+    mc = ModelChain.with_pvsyst(pvsyst_dc_snl_ac_system, location)
+    assert mc.dc_model == mc.pvsyst
+
+
+def test_with_sapm(sapm_dc_snl_ac_system, location):
+    mc = ModelChain.with_sapm(sapm_dc_snl_ac_system, location)
+    assert mc.dc_model == mc.sapm
+
+
+def test_with_pvwatts(pvwatts_dc_pvwatts_ac_system, location):
+    mc = ModelChain.with_pvwatts(pvwatts_dc_pvwatts_ac_system, location)
+    assert mc.dc_model == mc.pvwatts_dc
+
+
 @pytest.mark.parametrize('strategy, expected', [
     (None, (32.2, 180)), ('None', (32.2, 180)), ('flat', (0, 180)),
     ('south_at_latitude_tilt', (32.2, 180))