feat(vite): allow setting custom cwd path

[polvallverdu]

closes #13748

I have a monorepo with a package being a sveltekit app. I do unit testing, but it was completely failing when running vitest from the monorepo due to aliases not working, and mainly, the vite sveltekit plugin not finding the svelte.config.js file.

I fixed it with a patch allowing to override the cwd (solution proposed on the linked issue), and setting the cwd like this:

const __dirname = path.dirname(fileURLToPath(import.meta.url));

export default defineConfig({
  plugins: [
    tailwindcss(),
      sveltekit({
      cwd: __dirname,
    }),
  ],
  test: {
    name: "redacted",
    projects: [
      {
        extends: "./vite.config.ts",
        test: {
          name: "client",
          browser: {
            enabled: true,
            provider: playwright(),
            instances: [{ browser: "chromium", headless: true }],
          },
          include: ["tests/**/*.svelte.test.ts"],
        },
      },
      {
        extends: "./vite.config.ts",
        test: {
          name: "server",
          environment: "node",
          include: ["tests/**/*.test.ts"],
          exclude: ["tests/**/*.svelte.test.ts"],
        },
      },
    ],
  },
});

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Preview: https://svelte-dev-git-preview-kit-15188-svelte.vercel.app/

[benmccann]

Please see #12420 (comment) and #12410 (comment). I'm not sure this is necessary

[elliott-with-the-longest-name-on-github]

I also think we should lean on monorepo tools for this if possible -- if you have a use case that doesn't work with pnpm --dir or some similar option, please share a reproduction!

[polvallverdu]

Please see #12420 (comment) and #12410 (comment). I'm not sure this is necessary

Main issue here is that, even though vitest correctly sets the root directory, the sveltekit plugin overrides it to process.cwd(), which is incorrect, and breaks monorepo compatibility. Maybe a better solution would be the sveltekit plugin to rely on the root from vitest (or vite) rather than process.cwd(), but that might be a bigger breaking change.

I also think we should lean on monorepo tools for this if possible -- if you have a use case that doesn't work with pnpm --dir or some similar option, please share a reproduction!

In CI a single vitest command tests all the packages of my monorepo, I don't think needing a different command for testing the sveltekit app package is good DX. I'll share a repro hopefully today.

[benmccann]

Maybe a better solution would be the sveltekit plugin to rely on the root from vitest (or vite) rather than process.cwd()

SvelteKit has to tell Vite where the root is. There's no way to do it in the other direction