Test deduce_nominal_power if power curve is None

Author: uvchik

tests/test_wind_turbine.py

@@ -50,6 +50,16 @@ def test_deduce_nominal_power(self):
         n131.deduce_nominal_power_from_power_curve()
         assert n131.nominal_power == 3000000.0
 
+    def test_error_deduce_nominal_power_withour_p_curve(self):
+        """Test method to deduce nominal_power from power curve"""
+        test_turbine_data = {'hub_height': 100,
+                             'rotor_diameter': 80,
+                             'turbine_type': 'N131/3050'}
+        n131 = WindTurbine(**test_turbine_data)
+        assert n131.nominal_power is None
+        with pytest.raises(ValueError, match="You can not deduce the"):
+            n131.deduce_nominal_power_from_power_curve()
+
     def test_wrong_url_load_turbine_data(self):
         """Load turbine data from oedb."""