Getting Random Numbers#

1. Create a new folder and move into it.
2. Initialize a new npm project and install dependencies:

   npm init
   npm install hardhat@2.22.3 @nomicfoundation/hardhat-toolbox @flarenetwork/flare-periphery-contracts
   

   We recommend using this version of Hardhat for testing as it is known to work well.
3. Create a new Hardhat project (More information in the Hardhat setup guide):

   npx hardhat init
   

4. You will not be using the sample project, therefore:
   • Remove contracts/Lock.sol
   • Remove test/Lock.js
5. Edit hardhat.config.js to specify the correct EVM version. Make sure you include the highlighted lines:
   hardhat.config.js

   require("@nomicfoundation/hardhat-toolbox");
   
   /** @type import('hardhat/config').HardhatUserConfig */
   module.exports = {
       solidity: {
           compilers: [{
               version: "0.8.17",
               settings: {
                   evmVersion: "london"
               },
           }],
       }
   };
   

6. Copy the Solidity code above into a new file called GetRandomNumber.sol in the contracts folder.
7. Compile with:

   npx hardhat compile
   

Testing smart contracts before deploying them is typically performed by forking the network or by using mock contracts. These instructions quickly show you how to use the former.

1. Build the Hardhat project following the previous instructions.
2. Include network information in the hardhat.config.js file. Make sure you include the highlighted lines:
   hardhat.config.js

   require("@nomicfoundation/hardhat-toolbox");
   
   /** @type import('hardhat/config').HardhatUserConfig */
   module.exports = {
       solidity: {
           compilers: [{
               version: "0.8.17",
               settings: {
                   evmVersion: "london"
               },
           }],
       },
       networks: {
           hardhat: {
               forking: {
                   url: 'https://flare-api.flare.network/ext/bc/C/rpc',
               },
           },
       },
   };
   

3. Copy the code below into a new file called TestGetRandomNumber.js in the test folder.
   TestGetRandomNumber.js

   const { expect } = require("chai");
   describe("Test Random Number", function () {
     let contract;
     beforeEach(async function () {
       contract = await ethers.deployContract("GetRandomNumber");
     });
   
     it("RandomNumber", async function () {
       const [randomNumber, isSecure, timestamp] = await contract.generateNumber();
       expect(randomNumber).to.be.at.least(
         1000000000000000000000000000000000000000n
       );
       expect(isSecure).to.be.true;
       expect(timestamp).to.be.gt(1695817332);
     });
   });
   

4. Run the test with:

   npx hardhat test
   

1. If you don't have Foundry installed, follow the instructions for your operating system in the Foundry's Installation guide.
2. Create a new Foundry project:

   forge init <PROJECT_NAME>
   

   This command creates a new directory called <PROJECT_NAME>. Use a name that suits your needs.
3. Move into the project's directory:

   cd <PROJECT_NAME>
   

4. Install dependencies with:

   forge install flare-foundation/flare-foundry-periphery-package
   

5. Remove the sample project that Foundry created for you, as you do not need it:
   • Remove src/Counter.sol
   • Remove test/Counter.t.sol
6. Copy the Solidity code above into a new file called GetRandomNumber.sol in the src folder.
7. Open the foundry.toml file, and add the following lines at the end:

   evm_version = "london"
   remappings = [ "@flarenetwork/flare-periphery-contracts/=lib/flare-foundry-periphery-package/src/"]
   

8. Compile with:

   forge build
   

Testing smart contracts before deploying them is typically performed by forking the network or by using mock contracts. These instructions quickly show you how to use the former.

1. Build the Foundry project following the previous instructions.
2. Copy the code below into a new file called GetRandomNumber.t.sol in the test folder.
   GetRandomNumber.t.sol

   // SPDX-License-Identifier: MIT
   pragma solidity ^0.8.0;
   
   // Import dependencies
   import "forge-std/Test.sol";
   import "../src/GetRandomNumber.sol";
   
   // Test Contract
   contract GetRandomNumberTest is Test {
       string private constant FLARE_RPC =
           "https://flare-api.flare.network/ext/bc/C/rpc";
       uint256 private flareFork;
   
       function setUp() public {
           flareFork = vm.createFork(FLARE_RPC);
       }
   
       function testRandomNumber() public {
           vm.selectFork(flareFork);
           GetRandomNumber randNumber = new GetRandomNumber();
   
           (uint256 _randomNumber, bool _isSecure, uint256 _timeStamp) = randNumber
               .getRandomNumber();
   
           assertGt(_randomNumber, 0, "Random Number expected to be > 0");
           assertTrue(_isSecure, "Expect to be true");
           assertGt(
               _timestamp,
               1695817332,
               "Timestamp expected to be greater than a known past block"
           );
       }
   }
   

3. Run the test with:

   forge test -vv