test: pr for tests refactor related to #355

[gabrieledm]

Explanation

Split PR for test refactor from the original one #355.

• Update/add tests for fee calculation, transaction TRX value extraction, confirmation rendering, and insufficient-balance UI behavior.
  • Followed guidelines to avoid the usage of beforeEach

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
Test-only changes and minor coverage config updates; no production logic modified in this diff.

Overview
Refactors large Jest suites to avoid shared beforeEach state by introducing per-test setup helpers and stricter mocks, and adds coverage for fee UI and TRX amount parsing. Jest coverage thresholds are nudged up slightly to match the new tests.

FeeCalculatorService.test.ts drops module-level as any mocks (including TronWeb) in favor of typed partial mocks and a withFeeCalculatorService wrapper that builds a fresh service and dependencies for each case. Smart-contract simulation mocks now attach ret on a spread of the real transaction instead of minimal stub objects.

ConfirmSignTransaction / render tests use a similar withSnapContext pattern with typed SnapClient, scan, assets, and fee calculator mocks. Context fixtures include isInsufficientBalance, with new cases asserting confirm is blocked and “Insufficient funds” is shown, and that render sets isInsufficientBalance: true when TRX cannot cover value plus fees.

transaction.test.ts adds tests for getTransactionTrxValue: native transfers, smart-contract call_value, and non-TRX asset transfers returning zero.

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[taran-a]

LGTM