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bettingpool.sol

pragma solidity >=0.4.22 <0.6.0;

contract BettingPool {

    // constructor
    uint public betDeadline;
    uint public secretDeadline;

    // phase 1 (bets)
    mapping (address => uint256) bets;
    mapping (address => bytes32) secretHashes;

    // phase 2 (secrets)
    // accumulated bets so far before the sender
    mapping (address => uint256) accumulatedBets;
    uint256 confirmedValue;
    uint256 random;

    constructor(uint betDuration, uint secretDuration) public {
        betDeadline = now + betDuration;
        secretDeadline = betDeadline + secretDuration;
        confirmedValue = 0;
        random = uint256(blockhash(block.number));
    }
    
    function placeBet(uint256 secretHash) external payable {
        require(msg.value > 0, "bet must be more than zero");
        require(now <= betDeadline, "betting is closed for this pool");
        require(bets[msg.sender] == 0, "sender has already placed a bet");
        
        // add participant to bet pool (address, bet, secret hash)
        secretHashes[msg.sender] = bytes32(secretHash);
        bets[msg.sender] = msg.value;
    }
    
    function computeSecretHash(uint256 secret) public pure returns (bytes32) {
        return sha256(abi.encode(secret));
    }
    
    function sendSecret(uint256 secret) external {
        require(now > betDeadline,  "betting is still open for this pool");
        require(now <= secretDeadline,  "secret is closed for this pool");
        uint256 bet = bets[msg.sender];
        require(bet > 0, "sender hasn't placed any bets");
        require(computeSecretHash(secret) == secretHashes[msg.sender],
            "secret doesn't match");
        require(accumulatedBets[msg.sender] == 0, "secret already sent");

        random ^= secret;
        
        accumulatedBets[msg.sender] = confirmedValue;
        confirmedValue += bet;
    }
    
    function collectReward() external returns (bool hasWon) {
        require(secretDeadline < now,
            "bet pool is not ready to collecting rewards yet.");
        require(bets[msg.sender] > 0, "sender hasn't placed any bets");
        require(address(this).balance > 0, "reward already collected");

        hasWon = didIWin();
        if (hasWon) {
            // if sender is winner: transfer this contract's balance
            msg.sender.transfer(address(this).balance);
        }
    }
    
    function didIWin() view public returns (bool) {
        require(bets[msg.sender] > 0, "sender hasn't placed any bets");
        
        uint256 betRange = random % confirmedValue;
        
        return accumulatedBets[msg.sender] <= betRange &&
               betRange < accumulatedBets[msg.sender] + bets[msg.sender];
    }
}

test_test.sol

pragma solidity >=0.4.0 <0.6.0;
import "remix_tests.sol"; // this import is automatically injected by Remix.

// file name has to end with '_test.sol'
contract test_1 {

  function beforeAll() public {
    // here should instantiate tested contract
    Assert.equal(uint(4), uint(3), "error in before all function");
  }

  function check1() public {
    // use 'Assert' to test the contract
    Assert.equal(uint(2), uint(1), "error message");
    Assert.equal(uint(2), uint(2), "error message");
  }

  function check2() public view returns (bool) {
    // use the return value (true or false) to test the contract
    return true;
  }
}

contract test_2 {
 
  function beforeAll() public {
    // here should instantiate tested contract
    Assert.equal(uint(4), uint(3), "error in before all function");
  }

  function check1() public {
    // use 'Assert' to test the contract
    Assert.equal(uint(2), uint(1), "error message");
    Assert.equal(uint(2), uint(2), "error message");
  }

  function check2() public view returns (bool) {
    // use the return value (true or false) to test the contract
    return true;
  }
}