fix: ensure sequential mock/unmock resolution (#9830)

hi-ogawa · claude · web-flow · commit 7c06598dbb49 · 2026-03-24T09:30:33.000+01:00
Co-authored-by: Claude Opus 4.6 &lt;noreply@anthropic.com&gt;
diff --git a/packages/vitest/src/runtime/moduleRunner/bareModuleMocker.ts b/packages/vitest/src/runtime/moduleRunner/bareModuleMocker.ts
@@ -152,27 +152,33 @@ export class BareModuleMocker implements TestModuleMocker {
       return
     }
 
-    await Promise.all(
-      BareModuleMocker.pendingIds.map(async (mock) => {
-        const { id, url, external } = await this.resolveId(
+    const resolveMock = async (mock: PendingSuiteMock) => {
+      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,
-          mock.importer,
+          id,
+          url,
+          external,
+          mock.type,
+          mock.factory,
         )
-        if (mock.action === 'unmock') {
-          this.unmockPath(id)
-        }
-        if (mock.action === 'mock') {
-          this.mockPath(
-            mock.id,
-            id,
-            url,
-            external,
-            mock.type,
-            mock.factory,
-          )
-        }
-      }),
-    )
+      }
+    }
+
+    // group consecutive mocks of the same action type together,
+    // resolve in parallel inside each group, but run groups sequentially
+    // to preserve mock/unmock ordering
+    const groups = groupByConsecutiveAction(BareModuleMocker.pendingIds)
+    for (const group of groups) {
+      await Promise.all(group.map(resolveMock))
+    }
 
     BareModuleMocker.pendingIds = []
   }
@@ -368,6 +374,20 @@ function slash(p: string): string {
   return p.replace(windowsSlashRE, '/')
 }
 
+function groupByConsecutiveAction(mocks: PendingSuiteMock[]): PendingSuiteMock[][] {
+  const groups: PendingSuiteMock[][] = []
+  for (const mock of mocks) {
+    const last = groups.at(-1)
+    if (last?.[0].action === mock.action) {
+      last.push(mock)
+    }
+    else {
+      groups.push([mock])
+    }
+  }
+  return groups
+}
+
 const multipleSlashRe = /^\/+/
 // module-runner incorrectly replaces file:///path with `///path`
 function fixLeadingSlashes(id: string): string {
diff --git a/test/cli/test/mocking.test.ts b/test/cli/test/mocking.test.ts
@@ -392,6 +392,47 @@ test('mock works without loading original', () => {
   `)
 })
 
+test('doMock/doUnmock ordering is preserved in resolveMocks', async () => {
+  // This tests repeats doUnmock + doMock
+  //   vi.doUnmock('/mock-lib-0');
+  //   vi.doMock('/mock-lib-0', () => ({ value: 0 }));
+  //   vi.doUnmock('/mock-lib-1');
+  //   vi.doMock('/mock-lib-1', () => ({ value: 1 }));
+  //   ...
+  // then, all modules should be mocked
+  //   import('/mock-lib-0') // => { value: 0 }
+  //   import('/mock-lib-1') // => { value: 1 }
+  //   ...
+  const N = 20
+  const mockEntries = Array.from({ length: N }, (_, i) => `\
+vi.doUnmock('/mock-lib-${i}');
+vi.doMock('/mock-lib-${i}', () => ({ value: ${i} }));
+`).join('\n')
+  const importChecks = Array.from({ length: N }, (_, i) => `\
+await expect(import('/mock-lib-${i}')).resolves.toEqual({ value: ${i} });
+`).join('\n')
+
+  const { stderr, errorTree } = await runInlineTests({
+    './basic.test.js': `
+import { test, expect, vi } from 'vitest'
+
+test('many unmock + mock (all should mocked)', async () => {
+${mockEntries}
+${importChecks}
+})
+    `,
+  })
+
+  expect(stderr).toBe('')
+  expect(errorTree()).toMatchInlineSnapshot(`
+    {
+      "basic.test.js": {
+        "many unmock + mock (all should mocked)": "passed",
+      },
+    }
+  `)
+})
+
 test.for([
   'node',
   'playwright',
