Parking Garage

Requirements

• Park a vehicle in a space that fits it, and reject it when the garage is full
• Support several vehicle sizes with different space requirements
• Issue a ticket on entry recording the space and the time
• Calculate a fee on exit from the elapsed time and the vehicle size
• Free the space when the vehicle leaves

Assumptions you may make

• One garage, several floors; you may assume a single process
• Fees are computed at exit — no pre-payment or reservations
• You may assume a clock is available for timestamps

Things the brief expects to exist

Candidates, not a design. How they relate is yours to decide.

Vehicle

Knows its identity and the size class it needs

ParkingSpace

Knows its size and whether it is occupied

Ticket

Records which vehicle took which space, and when

Garage

Finds a fitting space and releases it again

FeePolicy

Turns an elapsed duration into an amount

What this exercise is teaching

• Assign responsibilities so that no class both allocates space and prices it
• Model vehicle sizing without a chain of conditionals per size
• Put the pricing rule behind a seam so a second rule can be added

Once it works, make it survive these

• Add monthly pass holders who are never charged per hour
• Add electric bays that only certain vehicles may use
• Support a second garage with different pricing