fix(vitest): keep the browser condition out of Node in DOM tests

.changeset/vitest-ssr-no-browser-condition.md

@@ -0,0 +1,5 @@
+---
+'vite-plugin-solid': patch
+---
+
+In jsdom and happy-dom tests, Node no longer gets the `browser` condition for packages that Vitest leaves external. Node-only packages such as `msw/node` now load under Vitest 4 and later (#125).

examples/vite-6/package.json

@@ -8,7 +8,7 @@
     "preview": "vite preview",
     "test": "vitest --browser.headless --run",
     "test-dev": "vitest",
-    "test:jsdom": "NODE_OPTIONS=--import=./tests/deno-conditions.mjs vitest --run --config vitest.jsdom.config.ts --pool=forks"
+    "test:jsdom": "NODE_OPTIONS=--import=./tests/deno-conditions.mjs vitest --run --config vitest.jsdom.config.ts --pool=forks && node tests/node-conditions.mjs"
   },
   "devDependencies": {
     "@solidjs/testing-library": "^0.8.10",

examples/vite-6/tests/node-conditions.mjs

@@ -0,0 +1,41 @@
+// Vitest passes the `ssr` environment's conditions to Node as `--conditions`
+// for the packages it leaves external. In a jsdom test run the plugin used to
+// add `browser` there, so Node-only packages failed to load. For example,
+// `msw/node` imports `@mswjs/interceptors/ClientRequest`, whose `browser`
+// export is `null` (#125).
+//
+// Checks:
+// - jsdom: `client` keeps `browser`, `ssr` does not.
+// - node environment: `ssr` keeps `browser`, since its tests run there.
+import { resolveConfig } from 'vite';
+import solid from 'vite-plugin-solid';
+
+async function conditions(test) {
+  const resolved = await resolveConfig(
+    { mode: 'test', configFile: false, logLevel: 'silent', plugins: [solid()], test },
+    'serve',
+  );
+  return {
+    client: resolved.environments.client.resolve.conditions,
+    ssr: resolved.environments.ssr.resolve.conditions,
+  };
+}
+
+const failures = [];
+const jsdom = await conditions({ environment: 'jsdom' });
+if (!jsdom.client.includes('browser')) {
+  failures.push(`jsdom: client conditions lack browser: ${JSON.stringify(jsdom.client)}`);
+}
+if (jsdom.ssr.includes('browser')) {
+  failures.push(`jsdom: ssr conditions include browser: ${JSON.stringify(jsdom.ssr)}`);
+}
+const node = await conditions({ environment: 'node' });
+if (!node.ssr.includes('browser')) {
+  failures.push(`node: ssr conditions lack browser: ${JSON.stringify(node.ssr)}`);
+}
+
+if (failures.length) {
+  for (const failure of failures) console.error(`FAIL: ${failure}`);
+  process.exit(1);
+}
+console.log('PASS: jsdom tests keep browser out of the ssr conditions');

src/index.ts

@@ -218,6 +218,10 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin {
   // by the crawl in test mode. They are inlined with solid-js (see
   // `test.server.deps` below).
   const testRuntimeConsumers = new Set<string>();
+  // True when a DOM test run inlines the Solid runtime. The `ssr`
+  // environment then does not get the `browser` condition (see
+  // `configEnvironment` below).
+  let domTestRuntimeInlined = false;
 
   return {
     name: 'solid',
@@ -228,6 +232,7 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin {
       replaceDev = options.dev === true || (options.dev !== false && command === 'serve');
       projectRoot = userConfig.root;
       isTestMode = userConfig.mode === 'test';
+      domTestRuntimeInlined = false;
 
       if (!userConfig.resolve) userConfig.resolve = {};
       userConfig.resolve.alias = normalizeAliases(userConfig.resolve && userConfig.resolve.alias);
@@ -310,6 +315,11 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin {
               },
             };
           }
+          const environment = userTest.environment ?? test.environment;
+          domTestRuntimeInlined =
+            !options.ssr &&
+            !userTest.browser?.enabled &&
+            (environment === 'jsdom' || environment === 'happy-dom');
         }
         if (!userTest.browser?.enabled) {
           // vitest browser mode already has bundled jest-dom assertions
@@ -367,10 +377,22 @@ export default function solidPlugin(options: Partial<Options> = {}): Plugin {
           config.resolve.conditions = [...defaultServerConditions];
         }
       }
+      // Vitest passes the `ssr` environment's conditions to Node as
+      // `--conditions` for the packages it leaves external. With `browser`
+      // there, Node-only packages fail to load. For example, `msw/node`
+      // imports `@mswjs/interceptors/ClientRequest`, whose `browser`
+      // export is `null` (#125). DOM tests run in the `client` environment,
+      // and the Solid runtime is inlined in that case, so the `ssr`
+      // environment does not need `browser`.
+      const addBrowser =
+        isTestMode &&
+        !opts.isSsrTargetWebworker &&
+        !options.ssr &&
+        !(domTestRuntimeInlined && name === 'ssr');
       config.resolve.conditions = [
         'solid',
         ...(replaceDev ? ['development'] : []),
-        ...(isTestMode && !opts.isSsrTargetWebworker && !options.ssr ? ['browser'] : []),
+        ...(addBrowser ? ['browser'] : []),
         ...config.resolve.conditions,
       ];