mock-to-internals-migration

Migrating Vitest mocks to Bun requires converting vi.fn(), vi.spyOn(), and vi.mock() calls to Bun's internal mock system while enforcing strict procedural guardrails, barrel export audits, and mock spread validation to preserve test isolation.

Broken test isolation occurs during vi.mock() conversion when barrel import patterns are disrupted or real module exports are missing from mocks. Applying validation checklists and command transformation idempotency requirements prevents this flaky behavior.

Converting vi.spyOn and vi.fn calls involves running baseline tests, auditing barrel exports, transforming mock APIs to Bun internals, and verifying command transformation idempotency through dedicated reviewer and test engineer validation checklists.

Yes, Bun's internal mock system can preserve barrel exports by applying mock spread validation and barrel export audits during migration. This ensures migrated mocks retain real module exports and maintain full test suite integrity.

Missing real module exports after Vitest to Bun mock migration typically result from skipping barrel export audits or failing mock spread validation. Banning forbidden shortcuts and enforcing post-change test verification resolves these regressions.

Limitations include the prohibition of custom gating mechanisms and the inability to dismiss post-change test failures as pre-existing without verification. Strict pre- and post-migration validation checklists are mandatory to ensure full test suite integrity.