fix: add BalanceAt mock to prevent balance monitor race

[Fletch153]

Summary

Adds a default BalanceAt mock expectation to NewEthMocksWithStartupAssertions, preventing a data race when the EVM balance monitor is enabled.

Root Cause

NewEthMocksWithStartupAssertions sets up common mock expectations but omits BalanceAt. When a test enables the balance monitor (default behavior), its background SleeperTask worker calls BalanceAt on the mock client. With no matching expectation, testify hits its "unexpected method call" error path, which calls callString() → fmt.Sprintf("%#v", ctx) → reflect-reads the context. This races with concurrent context cancellation during test teardown.

Race stack trace (from CI)

Read by goroutine 3144:        // BalanceAt → mock.callString → fmt.Sprintf → reflect
  github.com/stretchr/testify/mock.callString()        mock.go:463
  github.com/stretchr/testify/mock.(*Mock).MethodCalled()  mock.go:507  ← ERROR PATH
  github.com/smartcontractkit/chainlink-evm/pkg/monitor.(*worker).checkAccountBalance()

Previous write by goroutine 2837:   // context cancel() during teardown
  sync/atomic.AddInt32()
  github.com/smartcontractkit/chainlink-common/pkg/services.StopRChan.CtxCancel.func1()

Note: mock.go:507 is the "method called over N times" / unexpected call error path — this only fires because there's no BalanceAt expectation at all.

Fix

One line: add BalanceAt with .Maybe() to the mock helper. This gives the balance monitor a matching expectation with unlimited repeatability, so callString() is never invoked.

Related

• Root cause fix (upstream): fix: eliminate data race in SleeperTask context lifecycle chainlink-common#1984
• Previous fix attempt: core/internal/testutils/evmtest: run service to ensure closure #21397
• Failing CI run: https://github.com/smartcontractkit/chainlink/actions/runs/24509952973/job/71638172320

[github-actions]

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[github-actions]

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[github-actions]

✅ No conflicts with other open PRs targeting develop

[Fletch153]

Closing in favor of the upstream root-cause fix in chainlink-common: smartcontractkit/chainlink-common#1984

The catch-all BalanceAt mock in the shared helper would shadow test-specific BalanceAt expectations (testify matches in registration order). The chainlink-common fix eliminates the race at the source by replacing the CtxCancel goroutine with a read-only context — no test changes needed in this repo.

[cl-sonarqube-production]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube

[trunk-io]

     

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