no-mixed-defineworkspace-and-test-projects

Disallow mixing defineWorkspace(...) and test.projects in the same config file.

Rule catalog ID: R034

Targeted pattern scope

vitest.workspace.*
vitest.config.*
vite.config.* when Vitest project topology is configured

What this rule reports

This rule reports files that combine both:

a defineWorkspace(...) call
a test.projects configuration path

Why this rule exists

Vitest project topology should be defined through one primary mechanism per file. Mixing workspace-style and test.projects style in one file is confusing and can produce brittle maintenance behavior.

❌ Incorrect

import { defineWorkspace } from "vitest/config";

const shared = {
    test: {
        projects: [{ test: { name: "browser" } }],
    },
};

export default defineWorkspace([shared]);

✅ Correct

import { defineWorkspace } from "vitest/config";

export default defineWorkspace([
    {
        test: { name: "unit" },
    },
]);

Behavior and migration notes

the rule reports once per file when mixed topology is detected
choose one approach per file: workspace-driven or test.projects-driven

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 repository intentionally combines both topology styles within single files and the pattern is well-documented for contributors.

Package documentation

Vitest projects/workspaces

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​