Rollup plugin warnings are not shown

[nolanlawson]

Clear and concise description of the problem

As a developer using Vitest, I would like any Rollup plugins using the this.warn API to automatically show the warnings in the console while I am running tests, so that I know there might be issues in the plugin that I should fix.

This actually seems to work out-of-the-box today with Vite (minimal repro):

[plugin:custom-rollup-plugin] [plugin custom-rollup-plugin] I am warning you!! (x4)

However, a similar repro with Vitest does not show any warnings when running vitest.

Suggested solution

By default, I think Rollup warnings should be shown in the console. Perhaps there could also be a way to disable this default behavior, or to handle the warnings in vitest.config.js.

Alternative

I'm not aware of any way to surface Rollup plugin warnings using current Vitest. I apologize if I missed something in the docs!

Additional context

$ node --version
v20.11.0
$ npm --version
10.4.0

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[hi-ogawa]

This is likely because of Vitest setting logLevel: "error" to reduce unnecessary logs for normal Vitest use cases:

vitest/packages/vitest/src/node/create.ts

Lines 33 to 34 in cb02be1

	const config: ViteInlineConfig = {
	logLevel: 'error',

I think this default should be fine, but to workaround this, you can use a plugin to change logLevel. Here is an example:
https://stackblitz.com/edit/vitest-dev-vitest-or5xkk?file=vite.config.ts

    {
      name: 'force-vite-log',
      config(config, env) {
        delete config.logLevel;
      },
    },