feat: unit tests for ab-testing services + rate-limiting indexes (#1249–#1252)

[demilade18-git]

Summary

Implements four issues in a single PR. Build clean, 70 new tests pass.

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#1249 — Add database indexes to the rate-limiting entity

src/rate-limiting/entities/rate-limiting.entity.ts

Added @Index decorators covering the columns used in common query paths:

Index	Columns	Rationale
IDX_rate_limiting_userId	userId	Primary per-user lookup
IDX_rate_limiting_endpoint	endpoint	Per-route filter
IDX_rate_limiting_userId_endpoint	userId, endpoint	Composite for the most frequent query
IDX_rate_limiting_windowStart	windowStart	Range/cleanup queries

src/migrations/1800000000000-add-rate-limiting-indexes.ts

TypeORM migration that creates the same indexes with IF NOT EXISTS guards so it is safe to apply on databases that were previously synchronised.

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#1250 — Unit tests for automated-decision.service.ts

Created src/ab-testing/automation/automated-decision.service.spec.ts.

Covers every public method with success and failure paths:

• autoSelectWinner — not-found, not-running, below duration threshold, not statistically significant
• isReadyForWinnerSelection — not-found, not-running, below threshold, ready path
• getDecisionRecommendations — not-found, not-running, not-ready
• autoAllocateTraffic — not-found, disabled flag, reallocation triggered

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#1251 — Unit tests for experiment.service.ts

Created src/ab-testing/experiments/experiment.service.spec.ts.

Covers: updateExperiment, addVariant, removeVariant, updateTrafficAllocation (invalid sum, not-found, transaction path), getExperimentResults, archiveExperiment, pauseExperiment, resumeExperiment — all with happy path and error path.

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#1252 — Unit tests for ab-testing-reports.service.ts

Created src/ab-testing/reporting/ab-testing-reports.service.spec.ts.

Covers: generateExperimentReport (success, not-found), getDashboardSummary (empty, status counts, filter applied), generatePerformanceComparisonReport (no data, winner present), exportExperimentData (not-found, CSV output), getExperimentTimeline (empty, with data).

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Closes #1249
Closes #1250
Closes #1251
Closes #1252

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[RUKAYAT-CODER]

Well done on the job done so far!
Kindly fix workflow to pass

[RUKAYAT-CODER]

Thank you for contributing to the project