test(core): fix flaky promise assertions in scanner spec

[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:

What is the current behavior?

3 tests in DependenciesScanner.insertModule suite (scanner.spec.ts:409,416,424) are broken chai-as-promised is not loaded so .rejectedWith throws Invalid Chai property. Even if loaded, the promise is not returned to Mocha, so assertions never actually run.

Issue Number: N/A

What is the new behavior?

chai-as-promised is imported and chai.use() called. The 3 assertion promises are returned to Mocha via return. Tests now correctly verify that insertModule rejects @Injectable(), @Controller(), and @Catch() only classes.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[coveralls]

Coverage Report for CI Build 0

Coverage remained the same at 89.912%

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:	8644
Covered Lines:	7772
Line Coverage:	89.91%
Relevant Branches:	2947
Covered Branches:	2389
Branch Coverage:	81.07%
Branches in Coverage %:	No
Coverage Strength:	56.62 hits per line

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💛 - Coveralls

[kamilmysliwiec]

i believe this has already been fixed here #16391