Ships have Itineraries that have Ports ;TLDR

As a tour representative,
So I can decide which destinations passengers visit,
I want a ship to take an itinerary which determines at which port it next docks.

We have to read the user story very carefully here to identify a new object Itinerary which has ports. It also appears the functionality of our Ship's dock method will change - a ship should now dock at the next port on an Itinerary instance.

Challenge

Create a new Itinerary object and refactor existing code to work with the new behaviour introduced by the above user story.

To complete this challenge, you will need to:

• Discuss with your classmates how the domain model now looks.
• Create a new test file, which should describe a new Itinerary object.
• Create a new test spec to check the new Itinerary object can be instantiated.
• Write the code that makes this test pass.
• Create a new test spec to check the new Itinerary object has a ports property.
• Write the code that makes this test pass.
• Refactor the current tests and code for Ship so that:
  • Ship has a previousPort property set to null.
  • The setSail method sets a previousPort property on the ship to the current port.
• Refactor the Ship test suite so a Ship takes an Itinerary object instead of a Port object. The Itinerary object will have 2 Port objects stored in an array on its ports property.
• Refactor the it can dock at a different port test so that no argument is passed to ship.dock, and asserts the currentPort to be the next port in the Itinerary instance. The tests will break.
• Write the code that makes the tests pass again.
• Add, commit with a meaningful message, and push to GitHub.