@effect/vitest compatibility with vite+

[deadcoder0904]

https://viteplus.dev/ uses vite-plus/test instead of vitest. I already adopted it because instead of having oxlint/oxfmt & other deps, I just now have one vp but it gives this error.

Its a bit hard to debug when you want to test using @effect/vitest.

I asked Opus 4.6 & it gave me this:

The issue is a **dual vitest instance** problem. `@effect/vitest` imports from `vitest`,
but the `vp test` runner uses its own internal vitest instance from `vite-plus-test`.

The `describe`/it calls register with one instance while the runner executes from another — so no tests are found.

**What's needed to use `@effect/vitest` exclusively:**

1. **Add `vitest` as an explicit devDependency**
— the pnpm override will resolve it to `@voidzero-dev/vite-plus-test`, ensuring a single instance
2. **Change the test script to `vitest run`** instead of `vp test`
— so the runner and `@effect/vitest` share the same vitest module
This ensures `@effect/vitest` imports the exact same `vitest` that the runner uses.

Concretely, in package.json:
```diff
  "devDependencies": {
    "@effect/vitest": "^0.28.0",
    "bun-types": "^1.3.10",
+   "vitest": "latest",
    "vite-plus": "latest"
  },
```
And the test script:
```diff
-  "vitest": "vp test",
+  "vitest": "vitest run",
```

The pnpm override `"vitest": "npm:@voidzero-dev/vite-plus-test@latest"`
already ensures `vitest` resolves to the vite-plus distribution.

Want me to make these changes
and revert the test files back to `@effect/vitest` imports?

So would love to know how to go about this? Obviously, vite+ is a bit worse DX right now so it might be the reason.

[deadcoder0904]

Okay, asked Opus 4.6 to solve it & it did.

I'll keep this open since I think it should automatically detect vite-plus/test directly without having to install vitest since in future, mostly vp will be common anyways but feel free to close it if you want.

Okay, one more note, you cannot use vp test but only vitest run as I have it as my bun vitest script in package.json:

"vitest": "vitest run",

So it prolly needs to be fixed.

---

Fix: Using @effect/vitest with vite-plus

Problem

@effect/vitest has import * as V from "vitest" internally. With vite-plus, the pnpm override "vitest": "npm:@voidzero-dev/vite-plus-test@latest" exists but only takes effect when vitest is actually declared as a dependency. Without it, pnpm never creates node_modules/vitest, so @effect/vitest can't resolve its peer — causing either "Cannot find package" or "No test suite found" errors.

Solution

Add vitest as an explicit devDependency. The pnpm override automatically remaps it to vite-plus-test:

{
  "devDependencies": {
    "@effect/vitest": "^0.28.0",
    "vitest": "latest",
    "vite-plus": "latest"
  },
  "pnpm": {
    "overrides": {
      "vitest": "npm:@voidzero-dev/vite-plus-test@latest"
    }
  }
}

Then use vitest run as the test script (not vp test), and import from @effect/vitest in test files:

import { describe, expect, it } from '@effect/vitest'

Why it works

Adding vitest to devDependencies forces pnpm to create the node_modules/vitest symlink (pointing to vite-plus-test via the override). Now @effect/vitest's internal import * as V from "vitest" resolves to the same vitest instance that the runner uses → test suites register correctly → it.scoped, it.effect, and TestClock all work.