Fixture scopes
Fixtures are created when first requested by a test, and are destroyed based on their scope:
function: the default scope, the fixture is destroyed at the end of the test.
class: the fixture is destroyed during teardown of the last test in the class.
module: the fixture is destroyed during teardown of the last test in the module.
package: the fixture is destroyed during teardown of the last test in the package.
session: the fixture is destroyed at the end of the test session.