add and skip problematic test for car emission factor

tests/unit/test_parameters.py

@@ -9,6 +9,7 @@
     PlaneEmissionParameters,
     HeatingEmissionParameters,
     ElectricityEmissionParameters,
+    CarEmissionParameters,
 )
 import pytest
 from pydantic import ValidationError
@@ -58,5 +59,18 @@ def test_emission_factors_electricity(emission_factors_test) -> None:
     assert co2e == co2e_expected
 
 
-def test_emission_factors_bus():
-    pass
+@pytest.mark.skip(
+    reason="No emission factor available, if defaults are used in combination with this user input"
+    "We first need to decide how to handle this"
+)
+def test_emission_factors_car(emission_factors_test) -> None:
+    """Test emission factors for car"""
+    size = "small"
+    co2e_expected = 0.1
+
+    params = CarEmissionParameters(size=size)
+
+    # Get the co2 factor
+    co2e = emission_factors_test.get(params.dict())
+
+    assert co2e == co2e_expected