Enable jest hoist transform when using next/jest

Fixes vercel#32539

Implements what was shared at vercel#32539 (comment).

packages/next/build/swc/options.js

@@ -38,6 +38,14 @@ function getBaseSWCOptions({
       },
 
       transform: {
+        // Enables https://github.com/swc-project/swc/blob/0359deb4841be743d73db4536d4a22ac797d7f65/crates/swc_ecma_ext_transforms/src/jest.rs
+        ...(jest
+          ? {
+              hidden: {
+                jest: true,
+              },
+            }
+          : {}),
         legacyDecorator: enableDecorators,
         react: {
           importSource: jsConfig?.compilerOptions?.jsxImportSource || 'react',

test/mock.test.js

@@ -0,0 +1,24 @@
+// home.test.js
+import router from 'next/router'
+// const router = require('next/router')
+// jest.setup.js
+jest.mock('next/router', () => ({
+  push: jest.fn(),
+  back: jest.fn(),
+  events: {
+    on: jest.fn(),
+    off: jest.fn(),
+  },
+  asPath: jest.fn().mockReturnThis(),
+  beforePopState: jest.fn(() => null),
+  useRouter: () => ({
+    push: jest.fn(),
+  }),
+}))
+
+describe(`Page / Home`, () => {
+  it(`call mocked`, async () => {
+    console.log(router)
+    expect(typeof router.useRouter).toBe('function') // mocked
+  })
+})