fix(vitest): resolve each inline project's own config under Vitest 5

.changeset/vitest-5-shared-server-projects.md

@@ -0,0 +1,5 @@
+---
+'@solidjs/vite-plugin': patch
+---
+
+Vitest 5 inline projects get the plugin's test configuration again (#369). Vitest 5 defaults `test.sharedViteServer` to `true`, so an inline project that only changes `test` options reuses the root Vite server and resolves its options from the raw root `test` block, without running the plugin's `config` hook. Such projects lost everything the hook injects: a `test.environment: 'node'` project kept the root's `browser` condition (`isServer` was `false`), and jsdom projects lost the `@testing-library/jest-dom` setup file and the `solid-js` `server.deps` handling. When the root config declares `test.projects` and leaves `test.sharedViteServer` unset, the plugin now sets it to `false` so every project resolves its own Vite config, as it did under Vitest 4. An explicit `sharedViteServer` value is respected.

README.md

@@ -1045,6 +1045,8 @@ test: {
 },
 ```
 
+The posture is chosen while each project resolves its own Vite config. Vitest 5 lets inline projects reuse the root Vite server instead (`test.sharedViteServer`, on by default), which skips that step, so the plugin sets `sharedViteServer: false` when the root config declares `test.projects`. Setting the option yourself overrides this; with `true`, every shared project runs with the root config's posture and without the injected `jest-dom` setup file.
+
 # Credits
 
 - [solid-js](https://github.com/solidjs/solid)

src/index.ts

@@ -1192,6 +1192,11 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin[] {
           test.environment = 'jsdom';
         }
 
+        // Vitest 5 inline projects reuse the root server and never run this hook (#369).
+        if (userTest.projects && userTest.sharedViteServer === undefined) {
+          test.sharedViteServer = false;
+        }
+
         if (serverTestPosture) {
           // The worker pool is shared across the whole vitest workspace and
           // imports externalized deps natively with `--conditions` derived