fix: Flaky test with the FeeEstimationQuery e2e test

[manishdait]

Description:
This PR addresses flaky failures in the integration test with FeeEstimateQuery would fail because the FeeEstimationService had not yet started after a fresh Hiero Solo Mirror Node start.

Changes Made:

• Added wait_for_fee_estimation_service_ready to probe the service using an INTRINSIC mode query. This ensures the service is actually functional before the test suite proceeds.

Related issue(s):

Fixes #2275

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[coderabbitai]

Walkthrough

Fee estimation query integration tests now wait for the mirror-node FeeEstimationService to become ready before execution. Module-level globals track polling state, a readiness helper probes with an intrinsic fee transaction until success or timeout, and a synchronization helper adds fixed delay. All four test variants invoke these helpers consistently.

Changes

Fee Estimation Readiness Polling

Layer / File(s)	Summary
Readiness polling infrastructure and first test update tests/integration/fee_estimate_query_e2e_test.py	time import and module-level _fee_estimation_ready and _fee_estimation_error globals track polling state. wait_for_fee_estimation_service_ready(env) polls FeeEstimateQuery with an intrinsic fee transaction until it succeeds or times out, raising a stored error. wait_for_sync() adds fixed delay for mirror-node synchronization. The main account-based fee estimate test calls both helpers before creating and following the transaction.
Test readiness updates across remaining variants tests/integration/fee_estimate_query_e2e_test.py	State-mode account fee estimation, chunked file-append fee estimation, and chunked topic-message fee estimation tests each invoke the readiness and sync helpers before transaction execution, applying the same polling pattern across all test variants.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix: Flaky test with the FeeEstimationQuery e2e test' clearly describes the main change: addressing flaky FeeEstimationQuery integration tests by adding service readiness checks.
Description check	✅ Passed	The description is directly related to the changeset, explaining the root cause (FeeEstimationService not ready after fresh node start) and the solution (wait_for_fee_estimation_service_ready helper).
Linked Issues check	✅ Passed	The PR fulfills the objective from issue #2275 by implementing a wait-for-service mechanism that ensures FeeEstimationService is ready before tests execute, directly addressing the flakiness during early network startup.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the flakiness issue in FeeEstimateQuery tests. The additions of wait_for_fee_estimation_service_ready and wait_for_sync helpers, plus module-level tracking variables, are all in-scope for addressing intermittent test failures.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 3

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

tests/integration/fee_estimate_query_e2e_test.py (1)

81-83: ⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Strengthen assertions to validate result structure and content.

All four tests only assert result is not None, which doesn't validate the actual fee estimation response. Integration tests should verify observable network behavior beyond success/failure.

Consider asserting on the result's structure and content:

• Does result contain fee amounts (node, network, service fees)?
• Are the returned fees reasonable (positive values, within expected ranges)?
• For chunked transactions, do the fees reflect the chunk count?

💪 Example of stronger assertions

 query = FeeEstimateQuery().set_transaction(tx)
 result = query.execute(env.client)

 assert result is not None
+assert result.node_fee is not None and result.node_fee.to_tinybars() > 0
+assert result.network_fee is not None and result.network_fee.to_tinybars() > 0
+assert result.service_fee is not None and result.service_fee.to_tinybars() >= 0

(Adjust field names based on actual FeeEstimateQuery result structure)

As per coding guidelines: "Tests must assert observable network behavior, not just SUCCESS" and "Validate resulting balances, ownership, and state changes (not just transaction success)."

Also applies to: 96-98, 112-114, 130-132

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: 4a709e65-3029-40cc-920f-de8516c992bf

📥 Commits

Reviewing files that changed from the base of the PR and between b56df16 and 668efdf.

📒 Files selected for processing (1)

• tests/integration/fee_estimate_query_e2e_test.py

[aceppaluni]

@manishdait Thank you for fixing the flakiness of the tests.

Questions addressed in DM in discord.

[AntonioCeppellini]

LGTM :D 🚀