anomaly2104 / lld-parking-lot

Repository for low level design solution of parking lot

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Low Level System Design - Parking lot

Problem Statement

Check here

Project Requirements

• JDK 1.8
• Maven
• For Unit Tests:
  • Junit 4
  • Mockito

Compiling/Building and running the unit tests

Go to the project root folder and then run: ./bin/setup.sh

Runing the project

NOTE: Before running, please make sure you do the above setup step. Otherwise it will not run. The project can be run as follows in one of the two ways:

1. Using file based input:: It accepts a filename as a parameter at the command prompt and read the commands from that file.
   ./bin/parking_lot.sh <input_filepath>
   Example: ./bin/parking_lot.sh ./file_input.txt
2. Using file based input:: This will run the program in the interactive shell mode where commands can be typed in.
   ./bin/parking_lot.sh

Further Enhancements:

• Dependency injection: Currently dependencies are injected manually. We can use some dependency injection framework like spring.
• Exit command: Exit command is currently coupled with interactive mode only which makes it non-reusable.
• Parking strategy: Parking strategy is currently associated with ParkingLotService. Instead of that, it makes more sense to associate it with ParkingLot.
• Mode: Mode checking is currently done in main function directly. There could be a factory for that.

lld-parking-lot's Issues

Why do you want addSlots in parkingLot when it is already initialized?

lld-parking-lot/src/main/java/com/uditagarwal/service/ParkingLotService.java

Line 35 in 9b7c0ed

parkingStrategy.addSlot(i);

Getting error in test, when running `mvn clean install`

Tests in error:
testCorrectSlotNumberForNonExistingRegistrationNumber(com.uditagarwal.commands.SlotForRegNumberCommandExecutorTest)
testInvalidCommand(com.uditagarwal.commands.SlotForRegNumberCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3
testCorrectSlotNumberForValidRegistrationNumber(com.uditagarwal.commands.SlotForRegNumberCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3
testValidCommand(com.uditagarwal.commands.SlotForRegNumberCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3
testCarsWithAColor(com.uditagarwal.commands.ColorToRegNumberCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3
testInvalidCommand(com.uditagarwal.commands.ColorToRegNumberCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3
testValidCommand(com.uditagarwal.commands.ColorToRegNumberCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3
testWhenNoCarsFoundWithAColor(com.uditagarwal.commands.ColorToRegNumberCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3
testCommandExecutionWhenParkingSucceeds(com.uditagarwal.commands.ParkCommandExecutorTest): Could not initialize class org.mockito.internal.creation.cglib.ClassImposterizer$3

Need of creating a refrence to hashmap

Can you help me in understanding the need of creating a new reference for hashmap slots named allSlots using the getter method? Considering we can use the class variable slots directly as this.slots.

lld-parking-lot/src/main/java/com/uditagarwal/model/ParkingLot.java

Lines 44 to 48 in 071f9a0

	final Map<Integer, Slot> allSlots = getSlots();
	if (!allSlots.containsKey(slotNumber)) {
	allSlots.put(slotNumber, new Slot(slotNumber));
	}
	return allSlots.get(slotNumber);

Getting error in test, when running `mvn clean install`

Getting error