🔒️ bump vitest and @vitest/coverage-v8

VITEST5_MIGRATION_FINDINGS.md

@@ -0,0 +1,98 @@
+# Narf Vitest 5 Migration Investigation - Findings
+
+## Branch
+
+`dependabot/npm_and_yarn/multi-d440b5915d` (commit `b8a7128`)
+
+## Change
+
+`vitest` and `@vitest/coverage-v8` bumped from `^3.1.1` → `^5.0.0`
+
+## Test Results
+
+6 test files failing (17 tests), 21 passing (96 tests)
+
+## Root Cause: vitest 5 Mock Scope Change
+
+In vitest 5, `vi.mock()` no longer applies to **transitive imports** of packages that resolve to ESM bundler entries. This is a fundamental behavioral change from vitest 3.
+
+### Evidence from Diagnostics
+
+| Test                               | vi.mock target | Import pattern | Result |
+| ---------------------------------- | -------------- | -------------- | ------ |
+| Direct `await import("vue")`       | `vue`          | Direct         | Works  |
+| Direct `await import("express")`   | `express`      | Direct         | Works  |
+| Local ESM → Local ESM transitive   | `_target`      | `await import` | Works  |
+| Local ESM → CJS transitive         | `express`      | `await import` | FAILS  |
+| Local ESM → CJS transitive         | `express`      | Static import  | Works  |
+| Local ESM → ESM-bundled transitive | `vue`          | Static import  | FAILS  |
+| Local ESM → ESM-bundled transitive | `vue`          | `await import` | FAILS  |
+
+### Key Pattern
+
+- **Pure CJS packages** (express): Mock works transitively with static `import`, but NOT with `await import()`
+- **ESM-bundled packages** (vue, vue-router, remult): Mock does NOT work transitively with either `await import()` or static `import`
+- **Local ESM modules**: Mock works transitively with both import styles
+
+### Why `service.test.ts` passes but `server.test.ts` fails
+
+`service.test.ts` mocks express AND exercises the mock directly in the test body. It doesn't depend on the mocked express being applied transitively to `./service.ts` — the test creates its own `app` via `express()` (which returns the mock).
+
+`server.test.ts` depends on `vi.mock("remult/remult-express", ...)` being applied when `./server.ts` is imported. Since `remult-express` is an ESM-bundled package, the mock isn't applied transitively.
+
+## Config Approaches Tried (All Failed)
+
+The following vitest config options were tested and did NOT resolve the mock propagation issue:
+
+1. `server.deps.inline: [/^@?remult/]` — Still 9/9 failures on server.test.ts
+2. `test.deps.optimizer.ssr.include: ["vue", "vue-router", "remult"]` — Still 9/9 failures on server.test.ts
+
+## Failing Files
+
+### 1. `src/client/app/index.test.ts` (3/3 fail)
+
+- Mocks `vue` (ESM-bundled) → `./index` loads real vue
+- `mockCreate`, `mockUse`, `mockMount` never called
+
+### 2. `src/client/app/router.test.ts` (3/3 fail)
+
+- Mocks `vue-router` (ESM-bundled) → `./router` loads real vue-router
+- `mockCreateRouter`, `mockCreateHistory` never called
+
+### 3. `src/client/app/remult.test.ts` (suite fail)
+
+- Mocks `remult` (ESM-bundled) → `./remult` loads real remult
+- `TypeError: () => rem is not a constructor` — the real `Remult` class fails
+
+### 4. `src/server/server.test.ts` (9/9 fail)
+
+- Mocks `remult/remult-express`, `remult/remult-knex` (ESM-bundled) → `./server` loads real versions
+- All mock functions report 0 calls
+
+### 5. `src/server/index.test.ts` (1/1 fail)
+
+- Mocks `express` and `./service` → `./index` loads `./service` which imports express
+- `mockService` never called
+
+### 6. `src/models/story.test.ts` (1/11 fail)
+
+- `mockEntity.mock.lastCall` is undefined — `@Entity` decorator mock never invoked
+- Other tests pass (decoratorCalls map IS populated for `Fields` decorators)
+
+## Remaining Fix Approaches
+
+### 1. Rewrite each test to mock at the correct level
+
+Instead of mocking dependencies, mock the exports of the module under test. This is the most reliable approach but requires significant rework of each failing test.
+
+### 2. Use `vi.importActual` + manual wiring
+
+For each test, import the actual module and manually inject mocked dependencies.
+
+### 3. Further config investigation
+
+There may be other vitest 5 config options (e.g., `deps.moduleDirectories`, custom Vite plugins) that could restore mock propagation. The vitest 5 migration guide should be consulted for the definitive list of mock-related config changes.
+
+## Recommendation
+
+Each failing test file needs individual attention to restructure the mocking strategy for vitest 5. The config-based approaches did not work.