From f8879a82f95e7640d379e1e4b3ef30dec4ff8f3a Mon Sep 17 00:00:00 2001
From: Hiroshi Ogawa <hi.ogawa.zz@gmail.com>
Date: Fri, 9 Jan 2026 19:58:35 +0900
Subject: [PATCH] fix(mocker): fix mock transform with class

---
 packages/mocker/src/node/esmWalker.ts | 11 +++++++
 test/core/test/injector-mock.test.ts  | 46 +++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/packages/mocker/src/node/esmWalker.ts b/packages/mocker/src/node/esmWalker.ts
index 41420995a03c..aae80e955b59 100644
--- a/packages/mocker/src/node/esmWalker.ts
+++ b/packages/mocker/src/node/esmWalker.ts
@@ -157,6 +157,17 @@ export function esmWalker(
           identifiers.push([node, parentStack.slice(0)])
         }
       }
+      else if (node.type === 'ClassDeclaration' && node.id) {
+        // A class declaration name could shadow an import, so add its name to the parent scope
+        const parentScope = findParentScope(parentStack)
+        if (parentScope) {
+          setScope(parentScope, node.id.name)
+        }
+      }
+      else if (node.type === 'ClassExpression' && node.id) {
+        // A class expression name could shadow an import, so add its name to the scope
+        setScope(node, node.id.name)
+      }
       else if (isFunctionNode(node)) {
         // If it is a function declaration, it could be shadowing an import
         // Add its name to the scope so it won't get replaced
diff --git a/test/core/test/injector-mock.test.ts b/test/core/test/injector-mock.test.ts
index 8e0f93831b20..0d581f84847a 100644
--- a/test/core/test/injector-mock.test.ts
+++ b/test/core/test/injector-mock.test.ts
@@ -1117,6 +1117,52 @@ const Baz = class extends Foo {}
     `)
   })
 
+  test('classDeclaration shadowing import', () => {
+    const input = `\
+import { Bar } from "./repro.js"
+{
+  class Bar {
+    test() {}
+  }
+  const Zoo = class Zoo extends Bar {}
+}
+`
+    expect(hoistSimpleCodeWithoutMocks(input)).toMatchInlineSnapshot(`
+      "vi.mock('faker');
+      const __vi_import_0__ = await import("./repro.js");
+      import {vi} from "vitest";
+
+      {
+        class Bar {
+          test() {}
+        }
+        const Zoo = class Zoo extends Bar {}
+      }"
+    `)
+  })
+
+  test('classExpression name shadowing import', () => {
+    const input = `\
+import { Foo } from "./foo.js"
+const Bar = class Foo {
+  static create() {
+    return new Foo()
+  }
+}
+`
+    expect(hoistSimpleCodeWithoutMocks(input)).toMatchInlineSnapshot(`
+      "vi.mock('faker');
+      const __vi_import_0__ = await import("./foo.js");
+      import {vi} from "vitest";
+
+      const Bar = class Foo {
+        static create() {
+          return new Foo()
+        }
+      }"
+    `)
+  })
+
   test('import assertion attribute', () => {
     expect(
       hoistSimpleCodeWithoutMocks(`