Merge pull request #4208 from Saty248/loadFixture_hardhat_reset_bug_issue_#4151

adding a function and editing the error message for the issue #4151

Author: alcuadrado

.changeset/wise-cheetahs-confess.md

@@ -0,0 +1,5 @@
+---
+"@nomicfoundation/hardhat-network-helpers": patch
+---
+
+Improve an error message and add utility to clear all the existing snaphosts.

packages/hardhat-network-helpers/src/errors.ts

@@ -17,7 +17,7 @@ export class FixtureSnapshotError extends CustomError {
     super(
       `There was an error reverting the snapshot of the fixture.
 
-This might be caused by using nested loadFixture calls in a test, for example by using multiple beforeEach calls. This is not supported yet.`,
+This might be caused by using hardhat_reset and loadFixture calls in a testcase.`,
       parent
     );
   }

packages/hardhat-network-helpers/src/helpers/reset.ts

@@ -1,12 +1,14 @@
 import type { NumberLike } from "../types";
+import { clearSnapshots } from "../loadFixture";
+
 import { getHardhatProvider, toNumber } from "../utils";
 
 export async function reset(
   url?: string,
   blockNumber?: NumberLike
 ): Promise<void> {
   const provider = await getHardhatProvider();
-
+  await clearSnapshots();
   if (url === undefined) {
     await provider.request({
       method: "hardhat_reset",

packages/hardhat-network-helpers/src/loadFixture.ts

@@ -68,3 +68,10 @@ export async function loadFixture<T>(fixture: Fixture<T>): Promise<T> {
     return data;
   }
 }
+
+/**
+ * Clears every existing snapshot.
+ */
+export async function clearSnapshots() {
+  snapshots = [];
+}

packages/hardhat-network-helpers/test/helpers/reset.ts

@@ -1,9 +1,7 @@
 import { assert } from "chai";
-
 import * as hh from "../../src";
 import { INFURA_URL } from "../setup";
 import { useEnvironment } from "../test-utils";
-
 describe("resetWithoutFork", function () {
   useEnvironment("simple");
 
@@ -56,3 +54,13 @@ describe("resetWithoutFork", function () {
     assert.equal(olderMainnetBlockNumber, mainnetBlockNumber - 1000);
   });
 });
+
+describe("should clear snapshot upon reset", function () {
+  useEnvironment("simple");
+  it("checks if the snapshot is cleared upon hardhat_reset", async function () {
+    const snapshotBeforeReset = await hh.takeSnapshot();
+    await hh.reset();
+    const snapshotAfterReset = await hh.takeSnapshot();
+    assert.equal(snapshotBeforeReset.snapshotId, snapshotAfterReset.snapshotId);
+  });
+});