feat: add pseudo random example

contracts/ExamplePseudoRandom.sol

@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.2;
+
+import "@redstone-finance/evm-connector/contracts/data-services/MainDemoConsumerBase.sol";
+
+contract ExamplePseudoRandom is MainDemoConsumerBase {
+  uint256[] generatedNFTIndexes;
+
+  function getPseudoRandomness() private view returns(uint256) {
+    bytes32 dataFeedId = bytes32("ENTROPY");
+    uint256 randomValue = getOracleNumericValueFromTxMsg(dataFeedId);
+
+    return uint256(
+      keccak256(
+        abi.encodePacked(
+          randomValue,
+          block.timestamp,
+          blockhash(block.number - 1),
+          blockhash(block.number)
+        )
+      )
+    );
+  }
+
+  // Generates a random number from 1 to maxValue
+  function generateRandomNumber(uint256 maxValue) public view returns(uint256) {
+    uint256 randomness = getPseudoRandomness();
+    return (randomness % maxValue) + 1;
+  }
+
+  // Firstly it generates a single random number (e.g. number of NFTs in a box)
+  // Then it generates the specified number of random numbers
+  function generateManyRandomNumbers(uint256 maxRandomNumbersCount, uint256 maxValue) public {
+    uint256 randomness = getPseudoRandomness();
+    uint256 randomNumbersCount = generateRandomNumber(maxRandomNumbersCount);
+    generatedNFTIndexes = new uint256[](randomNumbersCount);
+    for (uint256 i = 0; i < randomNumbersCount; i++) {
+      generatedNFTIndexes[i] = uint256(keccak256(abi.encode(randomness, i))) % maxValue + 1;
+    }
+  }
+
+  function getGeneratedNFTIndexes() public view returns(uint256[] memory) {
+    return generatedNFTIndexes;
+  }
+}

test/ExamplePseudoRandom.js

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+const { WrapperBuilder } = require("@redstone-finance/evm-connector");
+
+describe("ExamplePseudoRandom", function () {
+  let contract;
+
+  beforeEach(async () => {
+    // Deploy contract
+    const ExamplePseudoRandom = await ethers.getContractFactory("ExamplePseudoRandom");
+    contract = await ExamplePseudoRandom.deploy();
+  });
+
+  it("Build random NFT indexes", async function () {
+    // Wrapping the contract
+    const wrappedContract = WrapperBuilder.wrap(contract).usingDataService({
+      dataServiceId: "redstone-main-demo",
+      uniqueSignersCount: 1,
+      dataFeeds: ["ENTROPY"],
+    }, ["https://d33trozg86ya9x.cloudfront.net"]);
+
+    // Interact with the contract (getting oracle value securely)
+    const generateManyRandomNumbersTx = await wrappedContract.generateManyRandomNumbers(10, 10);
+    await generateManyRandomNumbersTx.wait();
+    const generatedNFTIndexes = await wrappedContract.getGeneratedNFTIndexes();
+    console.log({ generatedNFTIndexes });
+  });
+});