[v3] Automatically inherit common test config in inline projects #7225

Clear and concise description of the problem

Project configurations can be repetitive, it would be nice for us and for Vitest to have a clear path towards defining what is common and what is specific to that project in one place. Inline projects are a great tool for that, I'm so thankful they made it into Vitest.

However, extending doesn't quite work as I expected, here I expected the project to inherit globals: true:

{
  test: {
    globals: true,
    workspace: [
      {
        test: {
          name: "node",
          environment: "node",
        },
      },
    ],
  },
}

because otherwise any config defined at the root test is a noop when workspace exists, right?

Next I tried setting extends: true on the project to get it to work, but it didn't. I don't really know what it does by default, I suppose it's looking up the directory tree.

What did work was configuring extends: "./vitest.config.ts".

Suggested solution

I would like not having to configure extends on projects, I would like inheritance to just happen. If that makes sense for the direction of v3.

Alternative

Type definitions could be altered in a way that prohibits noop root configs in case workspace is defined, using a discriminated union.

Additional context

No response

Validations

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