Vue Router warning when page / is not defined

Environment

• Operating System: Darwin
• Node Version: v22.14.0
• Nuxt Version: 3.17.7
• CLI Version: 3.26.2
• Nitro Version: 2.12.2
• Package Manager: npm@11.2.0
• Builder: -
• User Config: compatibilityDate, devtools, modules
• Runtime Modules: @nuxt/test-utils/module@3.19.2
• Build Modules: -

Reproduction

https://github.com/JBustin/nuxt3-test-utils

Sorry, I would like to share a reproduction on Stackblitz, but I failed to get an effective install of nuxt3 + @nuxt/test-utils: https://stackblitz.com/edit/nuxt-starter-mygjuknd?file=package.json

Describe the bug

If I don't have any / page, we experiment some router warnings during test.

stderr | components/Header.nuxt.spec.ts
[Vue Router warn]: No match found for location with path "/"

stderr | components/Header.nuxt.spec.ts
[Vue Router warn]: No match found for location with path "/"

stderr | components/Header.nuxt.spec.ts
[nuxt] error caught during app initialization H3Error: Page not found: /

Additional context

Additionally, we expect to be able to mock the current route during the tests, because we have some different behavior regarding the format of the current route.

Start with the reproduction at github.com/JBustin/nuxt3-test-utils and the failing components/Header.nuxt.spec.ts test. Investigate test startup when no / page exists, along with the requested ability to mock the current route. Done means the test no longer emits the Vue Router or Nuxt page-not-found warnings and route mocking works for the described behavior.