test(common): improve test coverage for shared utils

[BrahimAbdelli]

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PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• [x] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update (formatting, local variables)
• [x] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Other... Please describe:

What is the current behavior?

• The shared isEmpty() utility handles multiple cases inconsistently:
  • Returns true for null, undefined, and empty arrays
  • Returns false for all other values (objects, strings, etc.)
• No type safety for array checks (requires manual Array.isArray guards)
• Critical packages like @nestjs/graphql depend on this exact implementation

Issue Number: N/A

What is the new behavior?

New Behavior

// Original (maintained)
export function isEmpty(value: unknown): boolean;

// New (recommended)
export function isEmptyArray(value: unknown): value is unknown[];

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

[coveralls]

Pull Request Test Coverage Report for Build c7002453-0d8f-4ba5-bb62-ae87c6b05d20

Details

• 63 of 64 (98.44%) changed or added relevant lines in 20 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 89.31%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/common/utils/shared.utils.ts	23	24	95.83%
<!--	Total:	63	64

Totals
Change from base Build c43a5ccd-88ab-4646-8716-e80989f2dd70:	0.002%
Covered Lines:	7160
Relevant Lines:	8017

---

💛 - Coveralls

[BrahimAbdelli]

Hi @kamilmysliwiec , is there anything else needed to get this merged? Happy to help if further changes are required !

[kamilmysliwiec]

Hey @BrahimAbdelli, everything looks great! I flagged this PR as "blocked" as there're a few changes that may introduce minor breaking changes in case someone relied on these utils in community packages