Blog testings

[Rinrin0413]

see https://testing-library.com/docs/svelte-testing-library/intro

• articleNameIsValid
• requiredMetadataIsProvided
• articleIsNotLongerTemplate

[Rinrin0413]

@sveltejs/vite-plugin-svelte requires svelte@"^4.0.0 or svelte@^5.0.0-next.0".
So gonna implement the testings after upgrading Svelte.

[Rinrin0413]

I cannot implement the testings due to some bugs(?).