From 8dcc4b9e884583bea18cc02c3b9cbe986a53f323 Mon Sep 17 00:00:00 2001
From: Hadrien Croubois <hadrien.croubois@gmail.com>
Date: Wed, 11 Jun 2025 19:48:25 +0200
Subject: [PATCH] Improve test of Blockhash.sol: all cases on supported and
 unsupported chains (#5732)

---
 test/utils/Blockhash.test.js | 101 +++++++++++++++--------------------
 1 file changed, 43 insertions(+), 58 deletions(-)

diff --git a/test/utils/Blockhash.test.js b/test/utils/Blockhash.test.js
index a3de2655e..574ae3eea 100644
--- a/test/utils/Blockhash.test.js
+++ b/test/utils/Blockhash.test.js
@@ -1,76 +1,61 @@
-const { ethers } = require('hardhat');
+const { ethers, network } = require('hardhat');
 const { expect } = require('chai');
-const { loadFixture, mine, mineUpTo, setCode } = require('@nomicfoundation/hardhat-network-helpers');
+const { loadFixture, mineUpTo } = require('@nomicfoundation/hardhat-network-helpers');
 const { impersonate } = require('../helpers/account');
 
-async function fixture() {
-  const mock = await ethers.deployContract('$Blockhash');
-  return { mock };
-}
-
 const HISTORY_STORAGE_ADDRESS = '0x0000F90827F1C53a10cb7A02335B175320002935';
 const SYSTEM_ADDRESS = '0xfffffffffffffffffffffffffffffffffffffffe';
 const HISTORY_SERVE_WINDOW = 8191;
 const BLOCKHASH_SERVE_WINDOW = 256;
 
+async function fixture() {
+  return {
+    mock: await ethers.deployContract('$Blockhash'),
+    systemSigner: await impersonate(SYSTEM_ADDRESS),
+    latestBlock: await ethers.provider.getBlock('latest'),
+  };
+}
+
 describe('Blockhash', function () {
-  before(async function () {
+  beforeEach(async function () {
     Object.assign(this, await loadFixture(fixture));
-
-    impersonate(SYSTEM_ADDRESS);
-    this.systemSigner = await ethers.getSigner(SYSTEM_ADDRESS);
   });
 
-  it('recent block', async function () {
-    await mine();
+  for (const supported of [true, false]) {
+    describe(`${supported ? 'supported' : 'unsupported'} chain`, function () {
+      beforeEach(async function () {
+        if (supported) {
+          await this.systemSigner.sendTransaction({ to: HISTORY_STORAGE_ADDRESS, data: this.latestBlock.hash });
+        } else {
+          // `setCode` in hardhat-network-helpers doesn't support empty code :/
+          await network.provider.request({ method: 'hardhat_setCode', params: [HISTORY_STORAGE_ADDRESS, '0x'] });
+        }
+      });
 
-    const mostRecentBlock = (await ethers.provider.getBlock('latest')).number;
-    const blockToCheck = mostRecentBlock - 1;
-    const fetchedHash = (await ethers.provider.getBlock(blockToCheck)).hash;
-    await expect(this.mock.$blockHash(blockToCheck)).to.eventually.equal(fetchedHash);
-  });
+      it('recent block', async function () {
+        // fast forward (less than blockhash serve window)
+        await mineUpTo(this.latestBlock.number + BLOCKHASH_SERVE_WINDOW);
+        await expect(this.mock.$blockHash(this.latestBlock.number)).to.eventually.equal(this.latestBlock.hash);
+      });
 
-  it('old block', async function () {
-    await mine();
+      it('old block', async function () {
+        // fast forward (more than blockhash serve window)
+        await mineUpTo(this.latestBlock.number + BLOCKHASH_SERVE_WINDOW + 1);
+        await expect(this.mock.$blockHash(this.latestBlock.number)).to.eventually.equal(
+          supported ? this.latestBlock.hash : ethers.ZeroHash,
+        );
+      });
 
-    const mostRecentBlock = await ethers.provider.getBlock('latest');
+      it('very old block', async function () {
+        // fast forward (more than history serve window)
+        await mineUpTo(this.latestBlock.number + HISTORY_SERVE_WINDOW + 10);
+        await expect(this.mock.$blockHash(this.latestBlock.number)).to.eventually.equal(ethers.ZeroHash);
+      });
 
-    // Call the history address with the most recent block hash
-    await this.systemSigner.sendTransaction({
-      to: HISTORY_STORAGE_ADDRESS,
-      data: mostRecentBlock.hash,
+      it('future block', async function () {
+        // check history access in the future
+        await expect(this.mock.$blockHash(this.latestBlock.number + 10)).to.eventually.equal(ethers.ZeroHash);
+      });
     });
-
-    await mineUpTo(mostRecentBlock.number + BLOCKHASH_SERVE_WINDOW + 10);
-
-    // Verify blockhash after setting history
-    await expect(this.mock.$blockHash(mostRecentBlock.number)).to.eventually.equal(mostRecentBlock.hash);
-  });
-
-  it('very old block', async function () {
-    await mine();
-
-    const mostRecentBlock = await ethers.provider.getBlock('latest');
-    await mineUpTo(mostRecentBlock.number + HISTORY_SERVE_WINDOW + 10);
-
-    await expect(this.mock.$blockHash(mostRecentBlock.number)).to.eventually.equal(ethers.ZeroHash);
-  });
-
-  it('future block', async function () {
-    await mine();
-
-    const mostRecentBlock = await ethers.provider.getBlock('latest');
-    const blockToCheck = mostRecentBlock.number + 10;
-    await expect(this.mock.$blockHash(blockToCheck)).to.eventually.equal(ethers.ZeroHash);
-  });
-
-  it('unsupported chain', async function () {
-    await setCode(HISTORY_STORAGE_ADDRESS, '0x00');
-
-    const mostRecentBlock = await ethers.provider.getBlock('latest');
-    await mineUpTo(mostRecentBlock.number + BLOCKHASH_SERVE_WINDOW + 10);
-
-    await expect(this.mock.$blockHash(mostRecentBlock.number)).to.eventually.equal(ethers.ZeroHash);
-    await expect(this.mock.$blockHash(mostRecentBlock.number + 20)).to.eventually.not.equal(ethers.ZeroHash);
-  });
+  }
 });