prefer-define-project

Prefer defineProject(...) over defineConfig(...) for inline Vitest project entries.

Rule catalog ID: R008

Targeted pattern scope

vitest.workspace.*
vitest.config.*
vite.config.* when Vitest uses test.projects
inline defineWorkspace([...]) project arrays
inline test.projects: [...] arrays

What this rule reports

This rule reports defineConfig(...) calls used directly inside inline Vitest project arrays.

Why this rule exists

defineProject(...) communicates that the object is a project entry, not a top-level Vitest config export.

That makes workspace intent easier to read in reviews and keeps the project API explicit.

❌ Incorrect

import { defineConfig, defineWorkspace } from "vitest/config";

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

✅ Correct

import { defineProject, defineWorkspace } from "vitest/config";

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

Behavior and migration notes

this rule only targets inline project entries
top-level vitest.config.* files can still use defineConfig(...)

ESLint flat config example

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

export default [vite.configs.vitest];

When not to use it

Disable this rule if your repository intentionally treats inline workspace entries and top-level configs as the same abstraction.

Package documentation

Vitest projects guide

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​