Allow empty instances in browser settings for better `projects` usage

[michaelhazan]

Clear and concise description of the problem

Currently it is required to have the instances array include at least one instance of a browser, this causes me to have a shared browser instance between all of my projects (which i'm trying to avoid as i want each of the projects to use a different instance configuration).

Important to note that this still fails even when i'm running a specific project (that has instances configured) like so:

pnpm vitest run --project=<project-name>

Suggested solution

What im suggesting is to allow instances to be empty / undefined and fail only if the project running doesnt have any specified instances, so this behavior will be allowed:

// vite.config.ts

import { defineConfig } from "vitest/config"

export default defineConfig({
    test: {
        //...
        browser: {
            //.. Some sort of custom config that will be shared throughout the projects
            instances: [], // Or not even defined ¯\_(ツ)_/¯
        },
        projects: [{
            extends: true,
            name: "project",

            browser: {
                instances: // This must be defined
            }
        }],
    }
});

Alternative

No response

Additional context

No response

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[sheremet-va]

Good idea! But we do need to print the error somewhere if no tests are not found (maybe in the "no found" error message?).

[michaelhazan]

maybe in the "no found" error message

sounds good to me 👍