test(common): Add unit tests for HttpErrorByCode

[Se3do]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• 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)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe: Add unit test coverage for HttpErrorByCode utility

What is the current behavior?

HttpErrorByCode has no unit tests. This utility maps 19 HTTP status codes
to their corresponding exception classes (e.g. 400 → BadRequestException).
It is used by 8 built-in pipes (validation, parse-int, parse-uuid, parse-float,
parse-enum, parse-date, parse-bool, parse-file) to throw the correct HTTP
exception on validation failure. A wrong mapping silently causes all these
pipes to throw the wrong exception across every NestJS application.

Issue Number: N/A

What is the new behavior?

Adds packages/common/test/utils/http-error-by-code.util.spec.ts covering:

• Each of the 19 status codes maps to the correct exception class
  (verified by reference equality)
• Total entry count is exactly 19 (catches silent additions or deletions)
• Each exception class is constructible (imports resolve at runtime)

Follows the same testCases.forEach data-driven pattern used in
http.exception.spec.ts.

Does this PR introduce a breaking change?

• Yes
• No

Other information

This change only adds test coverage and does not modify runtime behavior.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a new unit test suite to validate that HttpErrorByCode maps HTTP status codes to the expected exception classes.

Changes:

• Introduces a HttpErrorByCode spec verifying mapping correctness across a set of status codes.
• Adds assertions to ensure the mapping has no extra entries beyond the tested cases.
• Adds a constructibility check for each mapped exception.

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[coveralls]

Coverage Report for CI Build 374024

Coverage remained the same at 90.028%

Details

• Coverage remained the same as the base build.
• Patch coverage: No coverable lines changed in this PR.
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	8624
Covered Lines:	7764
Line Coverage:	90.03%
Relevant Branches:	2943
Covered Branches:	2386
Branch Coverage:	81.07%
Branches in Coverage %:	No
Coverage Strength:	56.73 hits per line

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💛 - Coveralls

[kamilmysliwiec]

doesn't look like something we'd need a unit test for