feat(package-managers): add bun support

[awaiden]

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) - Will update separately

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] 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?

The Nest CLI does not officially support Bun as a package manager. Users working in Bun-based environments have to manually specify another package manager or deal with fallback behaviors during project information display and package installation.

Issue Number: #3257

What is the new behavior?

This PR introduces official support for the Bun package manager:

• Added BunPackageManager and BunRunner to handle Bun-specific commands.
• Updated PackageManagerFactory to automatically detect Bun by looking for bun.lock files.
• Enhanced the info command to display the Bun version when it's the active package manager.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

Tested locally with bun.lock detection and version retrieval.

[Copilot]

Pull request overview

This PR adds support for Bun as a package manager in the NestJS CLI, allowing users to work seamlessly with Bun-based projects without manual workarounds.

Changes:

• Added BunPackageManager class and BunRunner to handle Bun-specific commands
• Updated PackageManagerFactory to detect Bun projects via lockfile and create Bun instances
• Enhanced package manager selection UI to include Bun as an option

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
lib/runners/bun.runner.ts	New runner implementation for executing Bun commands
lib/runners/runner.ts	Added BUN enum value for runner identification
lib/runners/runner.factory.ts	Added factory case for creating BunRunner instances
lib/package-managers/bun.package-manager.ts	New package manager implementation with Bun-specific CLI commands
lib/package-managers/package-manager.ts	Added BUN enum value for package manager identification
lib/package-managers/package-manager.factory.ts	Added Bun lockfile detection and BunPackageManager creation
lib/package-managers/index.ts	Exported new BunPackageManager class
actions/new.action.ts	Added Bun to package manager selection prompt
test/lib/package-managers/bun.package-manager.spec.ts	Comprehensive test suite for BunPackageManager

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Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

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Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

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Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

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[micalevisk]

see #2223

[awaiden]

Thanks for pointing out #2233 however, I'd like to clarify that the situation has significantly changed since then:

Since Bun v1.0.3 (September 2023), Bun has added full support for emitDecoratorMetadata and the Reflect Metadata API. This means NestJS now works perfectly with Bun as a runtime, not just as a package manager.

My Experience

I've been using Bun with NestJS in production on my own project (awaiden/haloidergisi) and have not encountered any issues with:

• Dependency injection
• Decorators (@Injectable(), @Controller(), etc.)
• Metadata reflection
• Any NestJS core features

My tsconfig.json includes:

{
  "compilerOptions": {
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true
  }
}

And everything works flawlessly with Bun v1.2+.

Why This PR is Safe Now

The concerns in #2223 were valid at that time (mid-2023), but:

1. Bun now supports emitDecoratorMetadata (since v1.0.3)
2. Bun has a stable lockfile format (bun.lock)
3. Bun is being used in production with NestJS by many developers
4. The risk of confusion is minimal since Bun is now a legitimate runtime option for NestJS

I believe the concerns from #2223 are no longer applicable, and adding Bun to the supported package managers list is now safe and appropriate.