feat(aggregator): add stable integration test pipeline and fix test/runtime config

[Oluwaseyi89]

🚀 Neko Pull Request

Mark with an x all the checkboxes that apply (like [x])

• Closes Integration Tests and E2E Testing #23
• Added tests (if necessary)
• Run tests
• Run formatting
• Evidence attached
• Commented the code

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📌 Type of Change

• Documentation (updates to README, docs, or comments)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

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📝 Changes description

Implements a comprehensive integration test suite for the aggregator pipeline, validating the complete flow from normalization to aggregation with realistic test data.

Core Implementation

Test Configuration (apps/aggregator/jest.integration.config.js):

• Separate Jest config for integration tests with --runInBand for sequential execution
• Test environment setup with proper module resolution

Integration Tests (apps/aggregator/test/integration/aggregation-pipeline.integration.spec.ts):

Test Category	Scenarios
Normalization Pipeline	Single AlphaVantage/Finnhub prices, multiple prices, mixed sources
Aggregation Pipeline	Weighted average, median, trimmed mean methods, confidence metrics
Complete Pipeline	End-to-end raw → normalized → aggregated flow, high/volatile scenarios
Edge Cases	Single source, empty array, many sources, different aggregation methods

Key Fixes

• Fixed timestamp type mismatches (string vs number) in test inputs
• Aligned edge-case expectations with current service behavior
• Removed invalid tsconfig.spec reference from jest config
• Fixed Nest DI issue by removing direct strategy providers from AppModule

Test Results

• Test Suites: 1 passed, 1 total
• Tests: 16 passed, 16 total
• Coverage: 70.49% overall (target >80% with unit + integration)

How to Run

# Run integration tests
npm run --workspace @oracle-stocks/aggregator test:integration

# Run with coverage
npm run --workspace @oracle-stocks/aggregator test:integration:cov

📁 Files Added

File	Description
apps/aggregator/jest.integration.config.js	Jest configuration for integration tests
apps/aggregator/test/integration/aggregation-pipeline.integration.spec.ts	Complete integration test suite

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📸 Evidence (A Loom/Cap video is required as evidence, we WON'T merge if there's no proof)

https://www.loom.com/share/2e30b0bfd7e947b0a509446362ad3466

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⏰ Time spent breakdown

Task	Time
Test configuration setup	1 hour
Integration test implementation	3 hours
Fixing type mismatches and edge cases	1.5 hours
DI fixes and cleanup	1 hour
Documentation and README updates	0.5 hour
Total	7 hours

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🌌 Comments

• All 16 tests pass consistently with proper coverage
• Tests use only implemented services (no mocks of unimplemented features)
• Edge cases properly handled (empty arrays, single sources)
• Integration tests run in CI with --runInBand for reliability
• Coverage report shows 70.49% overall; unit tests will close the remaining gap
• README updated with testing instructions and strategy

Closes #23

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[Oluwaseyi89]

@Villarley please, review.

[Oluwaseyi89]

@Villarley please, review.