Solidity Smart Contract Assignment: LotteryGame

Overview

In this assignment, you will implement a simple Ethereum-based lottery game where players can register, make guesses, and potentially win ETH prizes. This exercise will help you practice Solidity development fundamentals including:

• State variables and data structures
• Function implementation
• Event handling
• Basic randomness generation
• Testing with Foundry

Project Structure

lottery-game/
├── src/
│   └── LotteryGame.sol       # Main contract implementation
└── test/
    └── LotteryGame.t.sol     # Foundry tests

Assignment Tasks

1. Implement the LotteryGame Contract

Clone the Repository:

• Clone this repository to your local machine:

   git clone <repository-url>
  

• Move into the project directory:

  cd <repository-name>
  

You need to complete the implementation of the LotteryGame.sol contract by filling in all the TODOs:

• Declare state variables for tracking player information, prizes, and winners
• Implement the event declarations
• Complete the register() function to allow players to join the game
• Implement the guessNumber() function for players to make guesses
• Complete the distributePrizes() function to handle prize distribution
• Implement the getPrevWinners() function to view previous winners

2. Fix the Test File

• Rename all instances of SampleGame to LotteryGame in the test file
• Ensure the import path correctly points to your implementation
• If needed, implement any additional test cases to ensure full coverage

Game Rules

1. Players must stake exactly 0.02 ETH to register
2. Each player can make up to 2 guesses
3. Valid guesses are numbers between 1 and 9
4. Players who guess correctly are added to the winners list
5. Prizes are distributed equally among all winners
6. After distribution, the game state is reset for a new round

Implementation Requirements

LotteryGame.sol

Your implementation should include:

• A Player struct with attempts and active properties
• Mappings and arrays to track player information and game state
• Events for important game actions
• Functions for registration, guessing, and prize distribution
• A simple random number generator

Important Notes

• The _generateRandomNumber() function is already provided
• This is a simplified implementation that uses block properties for randomness
• For a production environment, a more secure random number generator would be required

Testing

Run the tests using Foundry:

forge test

Ensure all tests pass before submitting your assignment. The tests verify that:

1. Players can register with the correct amount
2. Registration fails with incorrect amounts
3. Guesses work within valid ranges
4. Unregistered players cannot make guesses
5. Players are limited to two attempts
6. Prizes cannot be distributed when there are no winners

Evaluation Criteria

Your implementation will be evaluated based on:

1. Correctness: All functions work as intended and pass the provided tests
2. Code Quality: Clean, well-documented, and efficient code
3. Security: Proper validation and error handling
4. Gas Efficiency: Optimized operations where possible

Hints

• Make sure all state variables are appropriately initialized
• Use proper access control for internal functions
• Remember to emit events at the appropriate times
• Consider edge cases in your implementation

Submission

Submit both your completed LotteryGame.sol contract and the fixed test file. Make sure your code compiles without errors and passes all the provided tests.

Good luck!