GLSP-1635: Migrate test stack to Vitest

[tortmayr]

What it does

Migrates the shared test stack from Mocha/nyc/chai/sinon to Vitest.

• Replace the Mocha/nyc/chai/sinon stack with Vitest and its v8 coverage
  provider across the monorepo
• Add the @eclipse-glsp/vitest-config package providing a ready-to-use
  shared flat config (explicit test API imports, mock auto-restore, v8
  coverage, per-file DOM opt-in, CI annotations), mirroring the sprotty
  test setup; drop the now-obsolete mocha-config and nyc-config packages
• Rework the config-test meta package to bundle the Vitest config and
  test dependencies in place of Mocha and nyc
• Port all CLI specs to the Vitest API (chai expect, sinon sandboxes/stubs
  → vitest expect/vi) and add vite.config.ts / vite.config.e2e.ts
• Update CLI and root scripts/dependencies accordingly and drop the bespoke
  coverage-report command in favor of vitest --coverage

Also:

• Switch the CI test workflow to Vitest

Part of: #1635

How to test

• Covered by CI workflows
• If you want to test locally

pnpm install
pnpm build
pnpm test       # unit specs via vitest run
pnpm test:e2e   # e2e specs via vitest run --config vite.config.e2e.ts

• Verified locally via pnpm test

Follow-ups

Consuming GLSP repos (glsp-client, glsp-server-node, etc.) need to migrate
their own test setup to @eclipse-glsp/vitest-config separately.

Changelog

• This PR should be mentioned in the changelog
• This PR introduces a breaking change (if yes, provide more details below for the changelog and the migration guide)

[Copilot]

Pull request overview

Migrates the monorepo’s shared test tooling from the Mocha/nyc/chai/sinon stack to Vitest, introducing a reusable @eclipse-glsp/vitest-config package and updating CLI tests/configuration and CI accordingly.

Changes:

• Replace Mocha/nyc-based test + coverage setup with Vitest + @vitest/coverage-v8, including new shared Vitest flat config.
• Update CLI unit/e2e tests from chai/sinon to Vitest APIs and add vite.config.ts / vite.config.e2e.ts.
• Remove obsolete Mocha/nyc config packages and adjust workspace hoisting/scripts and the GitHub Actions test workflow.

Reviewed changes

Copilot reviewed 62 out of 65 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tsconfig.eslint.json	Extend ESLint TS coverage to include vite.config*.ts files.
pnpm-workspace.yaml	Update workspace hoisting patterns and add peer-install setting; keep security overrides.
package.json	Simplify root devDependencies and align root test scripts with Vitest-based CLI tests.
dev-packages/vitest-config/README.md	New documentation for the shared Vitest config package.
dev-packages/vitest-config/package.json	Define the new @eclipse-glsp/vitest-config package metadata/exports/peers.
dev-packages/vitest-config/LICENSE	Add license file for the new package.
dev-packages/vitest-config/index.js	Implement the shared Vitest config (restoreMocks, include globs, v8 coverage, CI reporter).
dev-packages/vitest-config/index.d.ts	Provide types for the shared Vitest config package exports.
dev-packages/ts-config/tsconfig.json	Remove reflect-metadata from default types.
dev-packages/ts-config/package.json	Stop publishing the removed Mocha-specific tsconfig variant.
dev-packages/ts-config/mocha.json	Remove Mocha-specific tsconfig variant.
dev-packages/nyc-config/README.md	Remove obsolete nyc shared config documentation.
dev-packages/nyc-config/package.json	Remove obsolete nyc shared config package.
dev-packages/nyc-config/LICENSE	Remove obsolete nyc shared config license file.
dev-packages/nyc-config/index.json	Remove obsolete nyc shared config payload.
dev-packages/mocha-config/README.md	Remove obsolete Mocha shared config documentation.
dev-packages/mocha-config/.mocharc.json	Remove obsolete Mocha shared config payload.
dev-packages/config/package.json	Drop reflect-metadata from shared dev config dependencies.
dev-packages/config-test/README.md	Update meta test package docs to reference Vitest config usage.
dev-packages/config-test/package.json	Switch meta test package deps from Mocha/nyc/chai/sinon to Vitest + coverage-v8 + vitest-config.
dev-packages/cli/vite.config.ts	Add repo-root Vitest config entrypoint for CLI unit tests.
dev-packages/cli/vite.config.e2e.ts	Add CLI e2e Vitest config with extended timeouts and different include globs.
dev-packages/cli/tsconfig.json	Switch CLI TS config base from removed Mocha variant to the shared base config.
dev-packages/cli/tests/e2e/update-next.e2e.spec.ts	Port e2e test to Vitest imports.
dev-packages/cli/tests/e2e/repo/repo-vscode.e2e.spec.ts	Port e2e test to Vitest lifecycle APIs.
dev-packages/cli/tests/e2e/repo/repo-theia.e2e.spec.ts	Port e2e test to Vitest lifecycle APIs.
dev-packages/cli/tests/e2e/repo/repo-eclipse.e2e.spec.ts	Port e2e test to Vitest and use conditional skipping via skipIf.
dev-packages/cli/tests/e2e/repo/repo-core-clone.e2e.spec.ts	Port e2e test to Vitest and use it.skipIf.
dev-packages/cli/tests/e2e/repo/repo-core-build.e2e.spec.ts	Port e2e test to Vitest lifecycle APIs.
dev-packages/cli/tests/e2e/releng/version.e2e.spec.ts	Port releng e2e tests to Vitest and use conditional suite skipping via skipIf.
dev-packages/cli/tests/e2e/releng/prepare.e2e.spec.ts	Port releng e2e tests to Vitest and use conditional suite skipping via skipIf.
dev-packages/cli/tests/e2e/generate-index.e2e.spec.ts	Port e2e test to Vitest imports.
dev-packages/cli/tests/e2e/coverage-report.e2e.spec.ts	Remove e2e tests for the removed coverageReport command.
dev-packages/cli/tests/e2e/check-header.e2e.spec.ts	Port e2e test to Vitest imports.
dev-packages/cli/src/util/validation-util.spec.ts	Port unit tests from sinon sandboxes to vi.spyOn.
dev-packages/cli/src/util/process-util.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/util/package-util.spec.ts	Port unit tests from sinon to vi.spyOn and vi.restoreAllMocks.
dev-packages/cli/src/util/glsp-repo-util.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/util/git-util.spec.ts	Port unit tests from sinon to vi.spyOn and Vitest mock call assertions.
dev-packages/cli/src/util/file-util.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/update-next.spec.ts	Port unit tests from sinon to Vitest spies/mocks.
dev-packages/cli/src/commands/repo/workspace.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/repo/switch.spec.ts	Port unit tests from sinon to Vitest spies/mocks.
dev-packages/cli/src/commands/repo/start.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/repo/server-node.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/repo/run.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/repo/repo.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/repo/link.spec.ts	Port unit tests from sinon to Vitest spies/mocks and mock call assertions.
dev-packages/cli/src/commands/repo/fork.spec.ts	Port unit tests from sinon to Vitest spies/mocks and mock call assertions.
dev-packages/cli/src/commands/repo/common/utils.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/repo/clone.spec.ts	Port unit tests from sinon to Vitest spies/mocks and mock call assertions.
dev-packages/cli/src/commands/repo/build.spec.ts	Port unit tests from sinon to Vitest spies/mocks and mock call assertions.
dev-packages/cli/src/commands/releng/version.spec.ts	Port unit tests to Vitest imports.
dev-packages/cli/src/commands/releng/publish.spec.ts	Port unit tests from sinon to Vitest spies/mocks and mock call assertions.
dev-packages/cli/src/commands/releng/common.spec.ts	Port unit tests from sinon to Vitest spies/mocks.
dev-packages/cli/src/commands/coverage-report.ts	Remove the bespoke nyc-based coverage report command.
dev-packages/cli/src/cli.ts	Remove registration of the removed coverageReport command.
dev-packages/cli/src/cli.spec.ts	Remove CLI tests for the removed coverageReport command and port remaining tests to Vitest.
dev-packages/cli/README.md	Remove CLI documentation for the removed coverageReport command.
dev-packages/cli/package.json	Switch test scripts to Vitest and add config-test dependency.
dev-packages/cli/.nycrc	Remove nyc configuration (no longer used).
dev-packages/cli/.mocharc.json	Remove Mocha configuration (no longer used).
dev-packages/cli/.mocharc.e2e.json	Remove Mocha e2e configuration (no longer used).
.github/workflows/test.yml	Switch CI test step from pnpm test:ci + CTRF report publishing to Vitest-based reporting/annotations.

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