Fixtures can also be parametrized directly. When a fixture is parametrized, all tests that use the fixture will now run multiple times, once for each parameter. This is an excellent tool to use when we have variants of a fixture and each test that uses the fixture should also run with all variants.

In the previous chapter, we saw an example of parametrization using multiple implementations of a serializer:

@pytest.mark.parametrize(
    "serializer_class",
    [JSONSerializer, XMLSerializer, YAMLSerializer],
)
class Test:

    def test_quantity(self, serializer_class):
        serializer = serializer_class()
        quantity = Quantity(10, "m")
        data = serializer.serialize_quantity(quantity)
        new_quantity = serializer.deserialize_quantity(data)
        assert new_quantity == quantity

    def test_pipe(self, serializer_class):
       ...