toanhoang
7e1351bde2
Root-cause fix for cross-file DB pollution in the vitest suite, which surfaced as intermittent FK-violation failures once the suite hit 12 test files. tests/setup.ts previously mutated the global process.env.DATABASE_URL and relied on src/lib/prisma.ts's singleton picking it up, which is racy across files sharing a worker process (process.env isn't reset between files even though Vitest resets each file's module registry). fileParallelism: false only masked this. Now each test file's own tests/setup.ts creates its own throwaway Postgres database and vi.mock()s "@/lib/prisma" with a dedicated PrismaClient constructed via the explicit datasourceUrl option, so no mutable state is shared between files and fileParallelism can go back to its default (true). Verified with 4 consecutive full `npm test` runs (327/327 passing each time) and no leftover throwaway databases after each run.