def test_can_add_components_to_entities(world):
entity = world.create_entity()
component = Component()
assert not world.has_component(entity, Component)
world.add_component(entity, component)
assert world.has_component(entity, Component)
assert world.get_component(entity, Component) is component
def test_can_pass_a_default_when_getting_a_component(world):
entity = world.create_entity()
assert world.get_component(entity, Component, missing="foo") == "foo"
def test_getting_a_non_existent_component_is_an_error(world):
entity = world.create_entity()
with pytest.raises(NoSuchComponentError):
world.get_component(entity, Component)