fix(analytics): add RFC 4180 CSV cell escaping and formatting for CSV exports

[Dotify71]

Fixes

#245

Description

Currently, exportReposCSV, exportContributorsCSV, and exportTrendsCSV format CSV rows by directly joining array values with commas (.join(',')). When export fields (such as repository names, descriptions, or organization names) contain commas, double quotes, or newlines, the generated CSV file breaks column alignment when opened in Excel, Google Sheets, or CSV parsers.

Solution

• Introduced escapeCSVCell to properly handle and escape cells per RFC 4180 standards:
  • Encloses fields containing commas ,, double quotes ", or newlines \n in double quotes.
  • Escapes internal double quotes by doubling them ("").
• Added formatCSVRow helper to process every row before export.
• Added comprehensive unit tests in src/services/analytics.exportCSV.test.js.

Testing

• Executed npm test -- --run -> All 50 tests across 6 test suites passed.

Summary by CodeRabbit

• New Features

  • CSV exports now safely format values containing commas, quotation marks, or line breaks.
  • Embedded quotation marks are preserved correctly, formula-like values are neutralized, and rows use standard line separators.

• Tests

  • Added coverage for CSV value escaping and formatting across mixed data types and special characters.

[coderabbitai]

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📒 Files selected for processing (2)

• src/services/analytics.exportCSV.test.js
• src/services/analytics.js

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Walkthrough

The analytics service adds shared CSV escaping and row-formatting helpers. Repository, contributor, and trend exports use quoted cells, escaped quotes, formula-injection neutralization, and CRLF separators. Vitest tests cover helpers and generated export content.

Changes

Analytics CSV formatting

Layer / File(s)	Summary
CSV serialization helpers src/services/analytics.js, src/services/analytics.exportCSV.test.js	Adds exported escapeCSVCell and formatCSVRow helpers. Tests cover nullish values, unchanged values, formula-injection characters, quoted cells, and mixed rows.
Export integration and validation src/services/analytics.js, src/services/analytics.exportCSV.test.js	Updates repository, contributor, and trend exports to use the shared formatter and CRLF separators. Integration tests verify headers and escaped data rows. The Bus Factor comment spacing changes.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~15 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested labels: Typescript Lang

Suggested reviewers: rahul-vyas-dev

Merge Risk: ⚪ Minimal · up to 66b0e

CSV exports retain valid quoted embedded line breaks and use CRLF row separators. No actionable merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: adding RFC 4180 CSV escaping and formatting for analytics exports.
Linked Issues check	✅ Passed	Issue #245 requires RFC 4180 CSV handling for repository, contributor, and trend exports. The changes route headers and data rows through formatCSVRow. escapeCSVCell quotes cells that contain comm…
Out of Scope Changes check	✅ Passed	The CSV injection prefix neutralization, CRLF separators, exported helpers, and tests directly support safe, standards-compliant CSV export for issue #245. No unrelated change is identified in the pro…

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_{A rabbit checks each comma’s place
Quotes fold neatly into space
CRLF hops from row to row
Safe cells make the exports glow
Test ears twitch: the fields align
CSV burrows now parse fine}

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[coderabbitai]

Actionable comments posted: 2

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• 🪄 Fix CodeRabbit comments on this PR

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Inline comments:
In `@src/services/analytics.exportCSV.test.js`:
- Around line 29-31: Add focused integration tests for exportReposCSV,
exportContributorsCSV, and exportTrendsCSV in the existing analytics export test
suite. Use a download-boundary test double, invoke each export with
representative data, and assert the complete generated content includes CSV
escaping and CRLF row separators, while keeping the existing formatCSVRow unit
test separate.

In `@src/services/analytics.js`:
- Line 155: Update escapeCSVCell around the String(val) conversion to prefix
string values beginning with dangerous formula characters, including a leading
hyphen, with a literal apostrophe before CSV escaping. Apply this only to string
inputs so numeric cells remain unchanged, and add coverage for hyphen and other
formula prefixes plus ordinary strings and numbers.

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📥 Commits

Reviewing files that changed from the base of the PR and between 284b530 and a5562d4.

📒 Files selected for processing (2)

• src/services/analytics.exportCSV.test.js
• src/services/analytics.js

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[Dotify71]

Added RFC 4180 CSV cell escaping and comprehensive unit test coverage.

Summary of changes:

• Implemented escapeCSVCell and formatCSVRow to properly wrap cells containing commas, double quotes, and newlines.
• Neutralized CSV injection formula prefixes (=, +, -, @, \t, \r) for string values.
• Updated export row separators to CRLF (\r\n).
• Added unit and integration tests in analytics.exportCSV.test.js (11 tests passing).

[Dotify71]

@coderabbitai can you give a review in this pr :))

[coderabbitai]

@Dotify71 I will review pull request #244.

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[rahul-vyas-dev]

@Dotify71 please share the visuals of working code.