given
Set up the test scenario by providing past events that will be provided to the Decider.handle method as an event stream.
This step is also known as the Arrange step in Arrange, Act, Assert
In case this method isn't called, then the default value for _givenEvents is an empty list
Return
this GivenWhenThenScenario instance
Parameters
events
the past events related to the aggregate instance (CAN be empty)