Filter out stdout/stderr messages

Clear and concise description of the problem

I’m working on a LitHtml project and when you run it in development mode it logs a message to the console, that appears when I do test runs:

stderr | unknown test
Lit is in dev mode. Not recommended for production!
 See https://lit.dev/msg/dev-mode for more informat
ion.

When running my tests, I get this multiple times and it provides no value. I know I can use --silent to ignore all output, but I do want to see any other messages.

Suggested solution

I was picturing a configuration setting that you could set:

{
  ignoreConsoleMessages: {
    source: 'stderr' // 'stdout' | 'stderr'
    match: /Lit is in dev mode/
  }
}

Or similar. That way the developer can very explicitly ignore certain messages, but can still see all other messages.

If this is acceptable, I would be happy to make an attempt at implementation in a PR 👍

Alternative

I think I could solve this in user-land by using a stubbing library such as sinon, and mock the console methods. But I think this is something worth considering solving in the configuration layer.

Additional context

No response

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