fix: format leading uppercase acronyms correctly in camelCase

[swaraj792725]

Summary

Fixes #123.

Previously, camelCase(str) was implemented as lowerFirst(pascalCase(str)).

When an input string started with an all-uppercase acronym or word (e.g. APIBaseURL, XMLParser, HTTPSResponse), pascalCase preserved the segment (APIBaseURL), and lowerFirst only lowercased the first character (A), producing unexpected outputs like aPIBaseURL, xMLParser, and hTTPSResponse.

Fix

camelCase now lowercases the entire first segment of the split words (first.toLowerCase()) so leading acronyms are formatted as expected (apiBaseURL, xmlParser, httpsResponse).

Test Plan

• Added test cases in test/scule.test.ts for camelCase with leading uppercase acronyms (APIBaseURL -> apiBaseURL, XMLParser -> xmlParser, HTTPSResponse -> httpsResponse).
• Verified all 81 unit & typecheck tests pass cleanly.

Summary by CodeRabbit

• Bug Fixes
  • Improved camel-case formatting for words with acronyms and mixed capitalization. The first word now follows consistent casing rules, and later words are formatted consistently, including when normalization is enabled.
  • Empty strings, falsy inputs, and inputs that contain no usable words now return an empty string.
  • Formatting is more consistent for arrays of words and inputs with leading, trailing, or repeated separators.

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📥 Commits

Reviewing files that changed from the base of the PR and between 4f86974 and 78c4377.

📒 Files selected for processing (4)

• src/index.ts
• src/types.ts
• test/scule.test.ts
• test/types.test-d.ts

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📝 Walkthrough

Walkthrough

camelCase and its type-level equivalent now format the first word directly. They lowercase an uppercase first word and handle empty parts. Tests cover acronym inputs, arrays, and normalized behavior.

Changes

camelCase formatting

Layer / File(s)	Summary
Format camelCase words src/index.ts, src/types.ts, test/scule.test.ts, test/types.test-d.ts	The runtime function and type-level conversion format the first word and subsequent words directly. Tests cover empty inputs, arrays, leading acronyms, and normalized inputs.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Low

Merge Risk: ⚪ Minimal · up to 78c43

This change makes camelCase lowercase a leading acronym fully, and the type-level conversion matches that runtime behavior. The tests cover acronym, empty-input and array cases. No actionable merge-blocking risk remains.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 78c43

The change remains local string processing and introduces no evident new privileges, sensitive operations, or shared-state effects. Risk is limited primarily to changed outputs for existing callers; downstream uses of those outputs are not available for assessment.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The demonstrated direct effect is a changed formatted value returned to an existing caller, not increased authority or access to another asset. Any security significance arising from downstream use as an identifier or key remains unassessed because external consumers are unavailable.

Trust Boundaries and Controls

• inferred — Within the inspected call path, caller-controlled input remains data throughout conversion. The replacement algorithm does not introduce an identity transition or bypass an existing authorization control; this conclusion does not establish safety for unknown downstream applications.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	Issue #123 requires default camelCase handling for MY_API_KEY and API_BASE_URL, with outputs myApiKey and apiBaseUrl. The implementation lowercases the first all-uppercase part, but it only …	Handle an all-uppercase underscore-separated input as normalized in the default camelCase path, and add default-option tests for MY_API_KEY and API_BASE_URL. Keep preservation tests for parseXML and myAPIKey.
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 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: correcting camelCase formatting for leading uppercase acronyms.
Out of Scope Changes check	✅ Passed	The source changes, type-level changes, and tests all modify or verify camelCase behavior related to issue #123. Empty-input handling and array tests support the changed implementation. No unrelated…

Full details: Linked Issues check

Explanation

Issue #123 requires default camelCase handling for MY_API_KEY and API_BASE_URL, with outputs myApiKey and apiBaseUrl. The implementation lowercases the first all-uppercase part, but it only lowercases later parts when normalize: true; default camelCase("MY_API_KEY") therefore produces myAPIKEY. The added test checks MY_API_KEY only with normalize: true. The implementation and tests do cover leading acronyms and preserve non-leading acronyms such as parseXML and myAPIKey.

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Warning

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🔧 ESLint

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src/index.ts

ESLint skipped: missing config or dependency (missing-dependency). The ESLint configuration references a package that is not available in the sandbox.

src/types.ts

ESLint skipped: the matched ESLint configuration already failed (missing-dependency).

test/scule.test.ts

ESLint skipped: the matched ESLint configuration already failed (missing-dependency).

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Actionable comments posted: 3

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Inline comments:
In @src/index.ts:
- Line 124: Update firstFormatted in camelCase to preserve mixed case in the
first array element; only lowercase a leading uppercase word, keeping
camelCase(["fooBar", "Baz"]) as "fooBarBaz".
- Line 128: Update CamelCase in src/index.ts so its first split word is fully
lowercased, matching the runtime camelCase behavior for acronyms such as
APIBaseURL. Preserve the existing Normalize behavior for remaining words, and
leave PascalCase and other type behavior unchanged.
- Around line 123-126: Update the first-word selection in camelCase to skip
leading empty parts before formatting, so camelCase("-foo") returns "foo". Use
the existing parts array and preserve the empty-input behavior when no non-empty
part exists.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: cb712a4e-6a12-4839-9600-270d44163766

📥 Commits

Reviewing files that changed from the base of the PR and between 5bc6804 and 4f86974.

📒 Files selected for processing (2)

• src/index.ts
• test/scule.test.ts

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 3 remain after this review.