no-vitest-file-parallelism-disabled

Disallow test.fileParallelism: false in committed Vitest config.

Rule catalog ID: R038

Targeted pattern scope

vitest.config.*
vitest.workspace.*
vite.config.* when Vitest test.fileParallelism is configured

What this rule reports

This rule reports explicit test.fileParallelism: false assignments.

Why this rule exists

Disabling file-level parallelism can reduce test throughput and hide order-dependent issues. In shared config, this is usually an accidental or temporary setting that should not persist.

❌ Incorrect

import { defineConfig } from "vitest/config";

export default defineConfig({
    test: {
        fileParallelism: false,
    },
});

✅ Correct

import { defineConfig } from "vitest/config";

export default defineConfig({
    test: {
        fileParallelism: true,
    },
});

Behavior and migration notes

this rule reports only explicit false
use local overrides if single-threaded debugging is needed temporarily

ESLint flat config example

import vite from "@typpi/eslint-plugin-vite";

export default [vite.configs.strict, vite.configs.vitest];

When not to use it

Disable this rule only if your project intentionally runs tests without file parallelism in committed shared config.

Package documentation

Vitest config reference

Targeted pattern scope​

What this rule reports​

Why this rule exists​

❌ Incorrect​

✅ Correct​

Behavior and migration notes​

ESLint flat config example​

When not to use it​

Package documentation​

Further reading​