release: v12.0.0 major release (approx. Q3 2026)

[kamilmysliwiec]

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: v12.0.0 release

Description

Approximate release window: early Q3 2026

A brief list of changes:

• nest new will now prompt users asking whether they want to use ESM or CJS for their project (ESM is the new default with vitest instead of jest)
• the entire source code has been migrated to ESM
• jest -> vitest for tests
• e2e tests added for all commands
• command classes have been refactored, and they now take context objects as inputs instead of non-types input and options arrays
• webpack builder has been deprecated
• rspack is the new default for monorepos

Does this PR introduce a breaking change?

• Yes
• No

Other information

[kamilmysliwiec]

A current version of this PR has been published under the next tag - @nestjs/cli@12.0.0-alpha.5

[Copilot]

Pull request overview

This PR prepares the Nest CLI v12 major release by migrating the codebase to ESM/NodeNext, switching the test runner from Jest to Vitest, and introducing rspack support (with webpack deprecated) alongside expanded e2e coverage.

Changes:

• Add Vitest configuration (unit + e2e) and migrate existing unit tests from Jest to Vitest.
• Migrate CLI/runtime code to ESM ("type": "module", .js import specifiers, NodeNext TS config) and refactor commands/actions to use typed context objects.
• Add rspack compiler + defaults and add e2e tests across core CLI commands.

Reviewed changes

Copilot reviewed 128 out of 131 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
vitest.e2e.config.ts	Adds Vitest config for e2e suite (timeouts, includes).
vitest.config.ts	Adds Vitest config for unit tests and excludes e2e.
tsconfig.json	Switches TS compilation to NodeNext/ES2022 and removes Jest types.
tools/postinstall.cjs	Post-install helper for test fixtures + vitest timeout patching.
tools/clean.js	Replaces gulp-based clean with a Node script to remove build artifacts.
test/lib/utils/get-default-tsconfig-path.spec.ts	Migrates test from Jest to Vitest + ESM import specifiers.
test/lib/schematics/schematic.option.spec.ts	Updates tests for boolean flag serialization changes + Vitest migration.
test/lib/schematics/nest.collection.spec.ts	Migrates to Vitest and updates ESM import paths.
test/lib/schematics/custom.collection.spec.ts	Migrates to Vitest and adds an ESM-safe mock for schematics tools.
test/lib/runners/schematic.runner.spec.ts	Updates module-path resolution expectations for ESM.
test/lib/readers/file-system.reader.spec.ts	Migrates to Vitest and updates reader imports.
test/lib/questions/questions.spec.ts	Migrates to Vitest and updates ESM import paths/types usage.
test/lib/package-managers/yarn.package-manager.spec.ts	Migrates to Vitest and updates ESM import paths/mocks.
test/lib/package-managers/pnpm.package-manager.spec.ts	Migrates to Vitest and updates ESM import paths/mocks.
test/lib/package-managers/package-manager.factory.spec.ts	Migrates to Vitest and updates typings for mock casting.
test/lib/package-managers/npm.package-manager.spec.ts	Migrates to Vitest and updates ESM import paths/mocks.
test/lib/configuration/nest-configuration.loader.spec.ts	Migrates to Vitest and updates ESM import paths.
test/lib/compiler/webpack/webpack-compiler.spec.ts	Adds coverage for webpack compiler deprecation + ESM rejection behavior.
test/lib/compiler/swc/swc-compiler.spec.ts	Updates SWC compiler unit tests for ESM module layout and Vitest mocks.
test/lib/compiler/rspack/rspack-defaults.spec.ts	Adds tests for new rspack defaults factory (incl. ESM mode).
test/lib/compiler/rspack/rspack-compiler.spec.ts	Adds unit tests for new rspack compiler behavior (watch, config merging).
test/lib/compiler/hooks/tsconfig-paths.hook.spec.ts	Reworks hook tests to assert both CJS and ESM output (drops snapshots).
test/lib/compiler/hooks/fixtures/unused-imports/src/main.ts	Updates fixture imports to include .js extension for ESM.
test/lib/compiler/hooks/fixtures/type-imports/src/main.ts	Updates fixture relative imports to include .js extension for ESM.
test/lib/compiler/hooks/snapshots/tsconfig-paths.hook.spec.ts.snap	Removes Jest snapshots now that assertions are explicit.
test/lib/compiler/helpers/get-value-or-default.spec.ts	Migrates helper test to Vitest and ESM import specifiers.
test/lib/compiler/helpers/get-rspack-config-path.spec.ts	Adds tests for new rspack config-path helper.
test/jest-config.json	Removes Jest test configuration.
test/e2e/new.command.e2e-spec.ts	Adds e2e coverage for nest new behaviors (language, strict, flags).
test/e2e/jest-e2e.json	Adds fixture Jest config used by generated projects in e2e scenarios.
test/e2e/info.command.e2e-spec.ts	Adds e2e coverage for nest info with/without deps installed.
test/e2e/helpers.ts	Adds shared e2e utilities for running/spawning CLI and scaffolding projects.
test/e2e/generate.command.e2e-spec.ts	Adds e2e coverage for nest generate across many schematic types/flags.
test/e2e/build.command.e2e-spec.ts	Adds e2e coverage for nest build (tsc/swc + monorepo webpack cases).
test/e2e/add.command.e2e-spec.ts	Adds e2e coverage for nest add (install + dry-run/skip-install).
test/actions/info.action.spec.ts	Migrates action tests to Vitest and adapts to private method access.
test/actions/build.action.spec.ts	Adds unit tests for builder dispatch behavior (webpack vs rspack).
package.json	Marks package as ESM, switches to Vitest scripts, updates deps/peers, replaces clean step.
lib/utils/tree-kill.ts	Renames internals to clearer “children” naming.
lib/utils/remaining-flags.ts	Updates commander integration to use Command + getOptionValue().
lib/utils/project-utils.ts	Removes hasValidOptionFlag and updates imports for ESM layout.
lib/utils/local-binaries.ts	Converts local command loader to async ESM import of local CLI commands.
lib/utils/load-configuration.ts	Updates imports for ESM layout.
lib/utils/is-module-available.ts	Uses createRequire for ESM-safe module resolution.
lib/utils/is-esm-project.ts	Adds helper to detect ESM projects via package.json "type": "module".
lib/ui/messages.ts	Updates ESM import specifier for emojis module.
lib/ui/index.ts	Updates barrel exports to explicit .js specifiers.
lib/schematics/schematic.option.ts	Changes boolean option rendering to --flag=false for false.
lib/schematics/nest.collection.ts	Updates imports for ESM layout.
lib/schematics/index.ts	Updates barrel exports to explicit .js specifiers.
lib/schematics/custom.collection.ts	Updates NodeWorkflow import to explicit /index.js for ESM.
lib/schematics/collection.factory.ts	Updates imports for ESM layout.
lib/schematics/abstract.collection.ts	Updates imports for ESM layout.
lib/runners/yarn.runner.ts	Updates import specifier for ESM layout.
lib/runners/schematic.runner.ts	Reworks module-path resolution to be ESM-safe via createRequire.
lib/runners/runner.factory.ts	Changes unsupported runner behavior from warn+continue to throwing an Error.
lib/runners/pnpm.runner.ts	Updates import specifier for ESM layout.
lib/runners/npm.runner.ts	Updates import specifier for ESM layout.
lib/runners/index.ts	Updates barrel exports to explicit .js specifiers.
lib/runners/git.runner.ts	Updates import specifier for ESM layout.
lib/runners/abstract.runner.ts	Updates UI import for ESM layout and aligns variable naming with lint config.
lib/readers/index.ts	Updates barrel exports to explicit .js specifiers.
lib/readers/file-system.reader.ts	Updates reader import specifier for ESM layout.
lib/questions/questions.ts	Removes any return annotation from generateInput factory.
lib/package-managers/yarn.package-manager.ts	Updates imports for ESM layout.
lib/package-managers/pnpm.package-manager.ts	Updates imports for ESM layout.
lib/package-managers/package-manager.factory.ts	Updates imports for ESM layout and simplifies catch handling.
lib/package-managers/npm.package-manager.ts	Updates imports for ESM layout.
lib/package-managers/index.ts	Updates barrel exports to explicit .js specifiers.
lib/package-managers/abstract.package-manager.ts	Migrates to fs/promises, ESM ora import, and tightens typing for package.json reads.
lib/configuration/nest-configuration.loader.ts	Updates imports, fixes a typo in comment, and simplifies defaulting logic.
lib/configuration/index.ts	Updates barrel exports to explicit .js specifiers.
lib/configuration/defaults.ts	Updates imports and adds default rspack config filename constant.
lib/configuration/configuration.ts	Extends builder types to include rspack and tightens several type definitions.
lib/configuration/configuration.loader.ts	Updates import specifier for ESM layout.
lib/compiler/webpack-compiler.ts	Adds webpack deprecation messaging, ESM project guard, and lazy-loads webpack deps.
lib/compiler/watch-compiler.ts	Updates imports for ESM layout.
lib/compiler/typescript-loader.ts	Reworks TS binary resolution for ESM (no module.paths reliance).
lib/compiler/swc/type-checker-host.ts	Updates imports and logs type-check errors to stderr.
lib/compiler/swc/swc-compiler.ts	ESM migration (createRequire/dirname), better error handling, and safer deep-merge own-property checks.
lib/compiler/swc/forked-type-checker.ts	Updates imports and sends errors to stderr.
lib/compiler/swc/constants.ts	Removes unused constant.
lib/compiler/rspack-compiler.ts	Introduces new Rspack compiler implementation with watch/build flows.
lib/compiler/plugins/plugins-loader.ts	ESM-safe plugin resolution via createRequire, fixes PluginAndOptions typing, improves error causes.
lib/compiler/plugins/plugin-metadata-printer.ts	Updates import specifier for ESM layout.
lib/compiler/plugins/plugin-metadata-generator.ts	Updates imports for ESM layout.
lib/compiler/hooks/tsconfig-paths.hook.ts	ESM-safe resolution updates and removes os.platform() dependency.
lib/compiler/helpers/tsconfig-provider.ts	Updates imports for ESM layout.
lib/compiler/helpers/get-webpack-config-path.ts	Updates signature to accept option records instead of Input[] arrays.
lib/compiler/helpers/get-value-or-default.ts	Changes option handling from Input[] to Record-based access for context objects.
lib/compiler/helpers/get-tsc-config.path.ts	Updates signature to accept option records instead of Input[] arrays.
lib/compiler/helpers/get-rspack-config-path.ts	Adds helper for rspack config path resolution from builder config.
lib/compiler/helpers/get-builder.ts	Updates signature to accept option records instead of Input[] arrays.
lib/compiler/helpers/delete-out-dir.ts	Updates imports for ESM layout.
lib/compiler/defaults/webpack-defaults.ts	Lazy-loads webpack-related deps and improves missing-dep errors for optional installation.
lib/compiler/defaults/swc-defaults.ts	Updates imports for ESM layout.
lib/compiler/defaults/rspack-defaults.ts	Adds rspack defaults factory with ESM/CJS support and optional plugin integration.
lib/compiler/compiler.ts	Updates imports and tightens extra arg typing.
lib/compiler/base-compiler.ts	Refines abstract method return types and restricts some methods to protected.
lib/compiler/assets-manager.ts	Updates imports and improves error message typing with cause.
gulpfile.js	Removes legacy gulp entrypoint for cleaning/build tooling.
eslint.config.js	Adds new flat-config ESLint setup for TS/ESM repo layout.
commands/start.command.ts	Migrates to context-based action invocation and updates commander types.
commands/new.command.ts	Migrates to context-based action invocation and updates language normalization logic.
commands/info.command.ts	Updates commander types and ESM imports.
commands/index.ts	Updates exports and adds context exports.
commands/generate.command.ts	Migrates to context-based invocation and updates --spec option default semantics.
commands/context/start.context.ts	Adds typed context interface for start command.
commands/context/new.context.ts	Adds typed context interface for new command.
commands/context/index.ts	Adds context barrel exports.
commands/context/generate.context.ts	Adds typed context interface for generate command.
commands/context/build.context.ts	Adds typed context interface for build command.
commands/context/add.context.ts	Adds typed context interface for add command.
commands/command.loader.ts	Adds ESM compatibility guard for global/local CLI mismatches and improves invalid command handling.
commands/build.command.ts	Migrates to context-based action invocation and adds rspack to builder help text.
commands/add.command.ts	Migrates to context-based action invocation and passes through remaining flags.
commands/abstract.command.ts	Updates commander type usage for ESM migration.
bin/nest.ts	Switches to new Command() for ESM, marks program as ESM-compatible, awaits local loader import.
actions/start.action.ts	Refactors to accept StartCommandContext and adapts runBuild/start lifecycle to ESM.
actions/new.action.ts	Refactors to accept NewCommandContext and updates prompting + schematic option mapping.
actions/info.action.ts	Refactors internal methods to private, uses padEnd, and updates ESM imports.
actions/index.ts	Updates exports to explicit .js specifiers.
actions/generate.action.ts	Refactors to accept GenerateCommandContext and updates schematic-option mapping.
actions/build.action.ts	Refactors to context-based inputs, adds rspack builder support, and updates ESM imports/dynamic imports.
actions/add.action.ts	Refactors to AddCommandContext and removes reliance on Input[] option scanning.
actions/abstract.action.ts	Simplifies AbstractAction API to a single context parameter.
.eslintrc.js	Removes legacy ESLint RC config in favor of flat config.
.eslintignore	Removes legacy ignore file (handled in flat config).
.circleci/config.yml	Updates CI to run Vitest and adds separate e2e job.

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[Copilot]

@kamilmysliwiec I've opened a new pull request, #3282, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@kamilmysliwiec I've opened a new pull request, #3283, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@kamilmysliwiec I've opened a new pull request, #3284, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@kamilmysliwiec I've opened a new pull request, #3285, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@kamilmysliwiec I've opened a new pull request, #3287, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@kamilmysliwiec I've opened a new pull request, #3288, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@kamilmysliwiec I've opened a new pull request, #3289, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@kamilmysliwiec I've opened a new pull request, #3290, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

Pull request overview

Copilot reviewed 128 out of 131 changed files in this pull request and generated 7 comments.

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