Issue 091: Add churn-analysis deterministic tests and golden fixtures

[orunganiekan]

Category: Backend
Complexity: 200 points
Labels: backend, wave-200

Context

churn-analysis.ts and test-churn-analysis.ts exist for subscriber churn analytics.

Problem

Analytics scripts can regress silently without golden fixtures in scripts/data.

Goal

Expand deterministic tests with checked-in fixtures and stabilize metric definitions (logos, grace lapses, cancels).

Scope

Includes: fixtures + tests.
Does NOT include: ML forecasting (see renewal-forecast separately).

Implementation Guidelines

• Files: churn-analysis.ts, test-churn-analysis.ts, data/ fixtures.

Acceptance Criteria

• Tests cover core metrics
• Fixtures documented
• Non-zero exit on assertion failure

Validation

npx tsx test-churn-analysis.ts or npm test script.

PR Expectations

The PR should include:

• Fixtures + tests

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[Olumide-01]

@Olumide-01 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi Maintainer, I would like to work on this issue because I understand the problem and have a clear approach to solving it. Please assign to me.

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[timilehin01010-byte]

@timilehin01010-byte has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

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[nobodieair]

@nobodieair has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I can fix this, please assign it to me

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[richiesplug]

@richiesplug has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

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[Risktaker001]

@Risktaker001 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi, I'd like to work on this issue. I understand the requirements and can implement the proposed changes while keeping the existing functionality intact. I'll also add the necessary tests, handle relevant edge cases, and verify that the project builds and all tests pass successfully.

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[iexwr]

@iexwr has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

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[d3vobed]

@d3vobed has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

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[drips-wave]

Congratulations, @iexwr! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @iexwr: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[iexwr]

Implemented — PR #992 (Closes #886) is open.

• Checked-in golden fixtures: scripts/data/churn-analysis-fixtures.json (7 fixtures covering cohort retention under new/retention logic, merchant churn breakdown with single-subscriber filtering, multi-cohort churn projection, grace-period cancelled-with-refund, empty/single-event edge cases).
• Fixture-driven runner in scripts/test-churn-analysis.ts with non-zero exit on assertion failure; restored SQLite/RPC fallback coverage.
• Added npm test script → npx tsx test-churn-analysis.ts.
• Validation: npm test passes (exit 0).