[Chai-matchers] Add polling mechanism when automine is not available by ChristopherDedominici · Pull Request #7997 · NomicFoundation/hardhat

ChristopherDedominici · 2026-02-24T13:49:00Z

Fixes: #7952.

Related to: #7993.

The underlying PR fixes the Hardhat invariant error, but it is not enough to resolve the bug. Hardhat needs to support polling for networks where automine is not defined, so this PR adds that feature.

TODO

Drop the development helper in the example project

…undation/hardhat into fix-hardhat-ethers-chai-matchers

changeset-bot · 2026-02-24T13:49:08Z

🦋 Changeset detected

Latest commit: 838b6a2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@nomicfoundation/hardhat-ethers	Patch
@nomicfoundation/hardhat-ethers-chai-matchers	Patch

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ChristopherDedominici · 2026-02-24T13:50:21Z

  });
 });
+
+describe("Matchers without automining", () => {


TMP file to test in example project that the bug is fixed, it will be removed before merging

I don't mind leaving it to be honest.

…undation/hardhat into chai-matchers-poll

…atchers-poll

…at into chai-matchers-poll

kanej

I think this is looking really solid.

I have left a few small comments and two larger tasks:

fast failing an invalid hash in emit: #7997 (comment)
waiting for the number of confirmations: #7997 (comment)

I also addressed the race condition (with help from Claude), can you look over my change: d3eef66 and resolve the converation if your happy?

@ChristopherDedominici I will re-review once your happy with those changes. I will do a manual test using your additions in the example-project (thanks for those - they are really helpful). I will also run the update version from within the OpenZeppelin mocha test suite to confirm we haven't regressed anything in the normal automine path.

…atchers-poll

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kanej

I ran through the example project tests and then ran the changed packages against OpenZeppelin to confirm the standard cases are still working.

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Copilot · 2026-03-25T16:04:56Z

+      const tx = await signer.sendTransaction({ to: signer.address });
+
+      let resolved = false;
+      const waitPromise = ethers.provider
+        .waitForTransaction(tx.hash, confirms)
+        .then((r) => {
+          resolved = true;
+          return r;
+        });
+
+      // mine the transaction into a block (1 confirmation)
+      await ethereumProvider.request({ method: "hardhat_mine" });
+
+      // give the polling loop time to check
+      await sleep(100);
+      assert.equal(
+        resolved,
+        false,
+        "should not resolve with only 1 confirmation",
+      );
+
+      // mine a second block (2 confirmations)
+      await ethereumProvider.request({ method: "hardhat_mine" });
+      await sleep(100);
+      assert.equal(
+        resolved,
+        false,
+        "should not resolve with only 2 confirmations",
+      );
+
+      // mine a third block (3 confirmations) — should now resolve
+      await ethereumProvider.request({ method: "hardhat_mine" });
+
+      const receipt = await waitPromise;
+      assert.equal(resolved, true);
+      assertIsNotNull(receipt);
+      assert.equal(receipt.hash, tx.hash);
+      assert.equal(receipt.status, 1);
+
+      // restore automining
+      await ethereumProvider.request({
+        method: "evm_setAutomine",
+        params: [true],
+      });


In this test, automining is disabled but restored only at the end of the happy path. If any assertion (or the awaited promise) throws before the restore call, later tests can run with automine still disabled and fail unpredictably. Wrap the automine toggle in a try/finally (or use a helper) so evm_setAutomine(true) always runs.

Suggested change

const tx = await signer.sendTransaction({ to: signer.address });

let resolved = false;

const waitPromise = ethers.provider

.waitForTransaction(tx.hash, confirms)

.then((r) => {

resolved = true;

return r;

});

// mine the transaction into a block (1 confirmation)

await ethereumProvider.request({ method: "hardhat_mine" });

// give the polling loop time to check

await sleep(100);

assert.equal(

resolved,

false,

"should not resolve with only 1 confirmation",

);

// mine a second block (2 confirmations)

await ethereumProvider.request({ method: "hardhat_mine" });

await sleep(100);

assert.equal(

resolved,

false,

"should not resolve with only 2 confirmations",

);

// mine a third block (3 confirmations) — should now resolve

await ethereumProvider.request({ method: "hardhat_mine" });

const receipt = await waitPromise;

assert.equal(resolved, true);

assertIsNotNull(receipt);

assert.equal(receipt.hash, tx.hash);

assert.equal(receipt.status, 1);

// restore automining

await ethereumProvider.request({

method: "evm_setAutomine",

params: [true],

});

try {

const tx = await signer.sendTransaction({ to: signer.address });

let resolved = false;

const waitPromise = ethers.provider

.waitForTransaction(tx.hash, confirms)

.then((r) => {

resolved = true;

return r;

});

// mine the transaction into a block (1 confirmation)

await ethereumProvider.request({ method: "hardhat_mine" });

// give the polling loop time to check

await sleep(100);

assert.equal(

resolved,

false,

"should not resolve with only 1 confirmation",

);

// mine a second block (2 confirmations)

await ethereumProvider.request({ method: "hardhat_mine" });

await sleep(100);

assert.equal(

resolved,

false,

"should not resolve with only 2 confirmations",

);

// mine a third block (3 confirmations) — should now resolve

await ethereumProvider.request({ method: "hardhat_mine" });

const receipt = await waitPromise;

assert.equal(resolved, true);

assertIsNotNull(receipt);

assert.equal(receipt.hash, tx.hash);

assert.equal(receipt.status, 1);

} finally {

// restore automining

await ethereumProvider.request({

method: "evm_setAutomine",

params: [true],

});

}

Copilot · 2026-03-25T16:04:56Z

+      let provider: EthereumProvider;
+
+      before(async () => {
+        ({ provider } = await initEnvironment("events"));
+      });
+


This block calls initEnvironment("events") a second time and uses that new provider to toggle automine/mine blocks, but the contracts/transactions in this suite were created with the ethers instance from the first initEnvironment call. If the second initEnvironment creates a separate in-process network/provider, these requests won’t affect the transactions under test, so the test may pass without actually exercising the non-automining behavior. Reuse the same provider obtained alongside ethers in the suite’s before() instead of creating a new environment here.

Suggested change

let provider: EthereumProvider;

before(async () => {

({ provider } = await initEnvironment("events"));

});

Copilot · 2026-03-25T16:04:56Z

+describe("Matchers without automining", () => {
+  it("emit should wait for the tx to be mined", async () => {
+    const { ethers, provider } = await hre.network.connect();


The PR description includes a TODO to “Drop the development helper in the example project”, but this change adds a new “Matchers without automining” section to the example project tests. If these tests are intended only as a temporary dev helper, consider removing them before merge (or update the PR description/TODO if they’re meant to stay as a permanent regression example).

ChristopherDedominici added 3 commits February 24, 2026 13:41

poll for revert and waitForTransaction

6dfa35c

tmp: bug repro

f144be3

Merge branch 'fix-hardhat-ethers-chai-matchers' of github.com:NomicFo…

157d989

…undation/hardhat into fix-hardhat-ethers-chai-matchers

github-actions Bot assigned kanej Feb 24, 2026

github-actions Bot added the status:triaging label Feb 24, 2026

ChristopherDedominici mentioned this pull request Feb 24, 2026

Fix hardhat-ethers-chai-matchers #7993

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ChristopherDedominici commented Feb 24, 2026

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ChristopherDedominici added no docs needed This PR doesn't require links to documentation no peer bump needed and removed status:triaging labels Feb 24, 2026

ChristopherDedominici assigned ChristopherDedominici and unassigned kanej Feb 24, 2026

ChristopherDedominici added this to Hardhat Feb 24, 2026

github-project-automation Bot moved this to Backlog in Hardhat Feb 24, 2026

ChristopherDedominici moved this from Backlog to In Progress in Hardhat Feb 24, 2026

ChristopherDedominici mentioned this pull request Feb 24, 2026

Hardhat Counter tests fail with Kurtosis ethereum-package (invariant was violated: receipt should not be null) #7952

Closed

ChristopherDedominici added 3 commits February 24, 2026 14:19

Merge branch 'fix-hardhat-ethers-chai-matchers' of github.com:NomicFo…

005bf7d

…undation/hardhat into chai-matchers-poll

add unit tests for waitForTransaction

08a5c71

Create honest-spies-play.md

670fd5b

ChristopherDedominici removed the no peer bump needed label Feb 24, 2026

Base automatically changed from fix-hardhat-ethers-chai-matchers to main February 24, 2026 16:00

ChristopherDedominici added 3 commits February 24, 2026 16:20

Merge branch 'main' of github.com:NomicFoundation/hardhat into chai-m…

30b0331

…atchers-poll

Merge branch 'chai-matchers-poll' of github.com:NomicFoundation/hardh…

e62710d

…at into chai-matchers-poll

Add peer bump files

df7f24a

ChristopherDedominici marked this pull request as ready for review February 24, 2026 16:30

ChristopherDedominici commented Feb 24, 2026

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Comment thread .peer-bumps.json

ChristopherDedominici moved this from In Progress to In Review in Hardhat Feb 24, 2026

update changeset for hh-chai

df3c60f

ChristopherDedominici requested a review from kanej February 25, 2026 16:24

kanej added 3 commits March 5, 2026 11:34

fix: avoid race condition between poll and timeout

d3eef66

needless whitespace for my clarity

fb64d99

Update v-next/hardhat-ethers/test/hardhat-ethers-provider.ts

cfea545

kanej requested changes Mar 5, 2026

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ChristopherDedominici added 2 commits March 9, 2026 14:33

Merge branch 'main' of github.com:NomicFoundation/hardhat into chai-m…

b8ed143

…atchers-poll

add PR bumps

7b0535e

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Comment thread v-next/hardhat-ethers/src/internal/hardhat-ethers-provider/hardhat-ethers-provider.ts

Comment thread v-next/hardhat-ethers/test/hardhat-ethers-provider.ts

Comment thread v-next/hardhat-ethers-chai-matchers/src/internal/matchers/reverted/revert.ts

ChristopherDedominici added 2 commits March 18, 2026 11:18

guard against invalid and ambiguous tx hash strings in emit matcher

e52c968

extract _isHardhatNetwork from loop

3361fb0

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ChristopherDedominici added 3 commits March 18, 2026 11:53

honour confirms parameter in waitForTransaction

9acae43

lint:fix

cc0c382

Merge branch 'main' of github.com:NomicFoundation/hardhat into chai-m…

5fcc07a

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kanej self-requested a review March 25, 2026 09:29

refactor: use util version of parseBytes32String

a8baa1a

kanej approved these changes Mar 25, 2026

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Merge branch 'main' into chai-matchers-poll

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ChristopherDedominici added this pull request to the merge queue Mar 26, 2026

Merged via the queue into main with commit 3268b33 Mar 26, 2026
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ChristopherDedominici deleted the chai-matchers-poll branch March 26, 2026 10:16

github-project-automation Bot moved this from In Review to Done in Hardhat Mar 26, 2026

github-actions Bot mentioned this pull request Mar 25, 2026

Version Packages (v3) #8076

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