test(vitest): share console setup and config defaults

[joshblack]

Adds a shared private @primer/vitest-config package for Vitest console-failure enforcement and shared config defaults. Vitest projects now consume a shared defineConfig wrapper so common setup can stay centralized while console enforcement remains opt-in for downstream cleanup PRs.

Changelog

New

• Shared Vitest setup package for console-failure enforcement.
• Shared @primer/vitest-config/config entrypoint that wraps defineConfig with common Vitest defaults.

Changed

• Vitest project configs now import defineConfig from @primer/vitest-config/config.
• Shared Vitest defaults now centrally apply __VITEST_FAIL_ON_CONSOLE__ and setupFiles.
• Shared setup now safely falls back when the injected console flag is unavailable in a given Vitest environment.

Removed

• N/A

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; configuration-only test infrastructure.

Testing & Reviewing

Validated with build, targeted Vitest runs for the affected packages/configs, type-check, lint, CSS lint, and format checks. A full aggregated npm test -- --run still hit an unrelated existing AnchoredOverlay browser-suite failure, but the affected Vitest config paths exercised by this PR passed in targeted runs.

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github-ui (Learn more about how to run integration tests)

[changeset-bot]

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Latest commit: a6439c2

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[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

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[Copilot]

Pull request overview

This PR introduces a new private workspace package (@primer/vitest-config) that centralizes Vitest setup for optional vitest-fail-on-console enforcement, and wires all existing Vitest project configs in the monorepo to load it.

Changes:

• Added packages/vitest-config workspace with an exported Vitest setup file (@primer/vitest-config/setup).
• Updated each package’s Vitest config (node + browser where applicable) to load the shared setup file and define __VITEST_FAIL_ON_CONSOLE__ based on process.env.VITEST_FAIL_ON_CONSOLE.
• Updated package-lock.json to include the new workspace and vitest-fail-on-console dependency.

Show a summary per file

File	Description
packages/vitest-config/tsconfig.json	Adds TS config for the new shared Vitest setup workspace.
packages/vitest-config/src/setup.ts	Implements opt-in vitest-fail-on-console setup behind a build-time flag.
packages/vitest-config/package.json	Declares the new private workspace package, its export, and dependency.
packages/styled-react/vitest.config.ts	Loads shared setup for node tests and defines the opt-in flag.
packages/styled-react/vitest.config.browser.ts	Loads shared setup for browser tests and defines the opt-in flag.
packages/react/vitest.config.mts	Loads shared setup for node tests and defines the opt-in flag.
packages/react/vitest.config.browser.mts	Loads shared setup for browser tests and defines the opt-in flag.
packages/postcss-preset-primer/vitest.config.ts	Loads shared setup for node tests and defines the opt-in flag.
packages/doc-gen/vitest.config.mts	Loads shared setup for node tests and defines the opt-in flag.
package-lock.json	Adds workspace link + locks vitest-fail-on-console (and dependency graph adjustments).

Copilot's findings

• Files reviewed: 9/10 changed files
• Comments generated: 0

[joshblack]

@copilot could you add a config entrypoint to vitest-config that exports a wrapper for defineConfig. vitest configs should pull from this instead (e.g. import {defineConfig} from '@primer/vitest-config/config') and then the helper should call defineConfig from vitest/config and merge in the input with the defaults we want in each config (like __VITEST_FAIL_ON_CONSOLE__ and setupFiles)

[Copilot]

@copilot could you add a config entrypoint to vitest-config that exports a wrapper for defineConfig. vitest configs should pull from this instead (e.g. `import {defineConfig} from '@primer/vitest-co...

Addressed in a6439c2. Added @primer/vitest-config/config, switched the Vitest project configs to import its defineConfig wrapper, and kept the shared setup resilient when the injected define is unavailable.