fix: batch consecutive same-action mocks in parallel

Resolve consecutive mock/unmock operations of the same type in parallel
using Promise.all, only going sequential when the action type changes.
This preserves correctness while avoiding unnecessary performance impact.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: hi-ogawa

packages/vitest/src/runtime/moduleRunner/bareModuleMocker.ts

@@ -152,24 +152,37 @@ export class BareModuleMocker implements TestModuleMocker {
       return
     }
 
-    for (const mock of BareModuleMocker.pendingIds) {
-      const { id, url, external } = await this.resolveId(
-        mock.id,
-        mock.importer,
-      )
-      if (mock.action === 'unmock') {
-        this.unmockPath(id)
-      }
-      if (mock.action === 'mock') {
-        this.mockPath(
-          mock.id,
-          id,
-          url,
-          external,
-          mock.type,
-          mock.factory,
-        )
+    // batch consecutive mocks of the same action type to resolve in parallel,
+    // but process different action types sequentially to preserve ordering
+    let i = 0
+    while (i < BareModuleMocker.pendingIds.length) {
+      const action = BareModuleMocker.pendingIds[i].action
+      const batch: typeof BareModuleMocker.pendingIds = []
+      while (i < BareModuleMocker.pendingIds.length && BareModuleMocker.pendingIds[i].action === action) {
+        batch.push(BareModuleMocker.pendingIds[i])
+        i++
       }
+      await Promise.all(
+        batch.map(async (mock) => {
+          const { id, url, external } = await this.resolveId(
+            mock.id,
+            mock.importer,
+          )
+          if (mock.action === 'unmock') {
+            this.unmockPath(id)
+          }
+          if (mock.action === 'mock') {
+            this.mockPath(
+              mock.id,
+              id,
+              url,
+              external,
+              mock.type,
+              mock.factory,
+            )
+          }
+        }),
+      )
     }
 
     BareModuleMocker.pendingIds = []