fix: should return the same spy instance when respy

e2e/spy/spyOn.test.ts

@@ -78,4 +78,15 @@ describe('test spyOn', () => {
     spy.mockReset();
     expect(util1.sayHi()).toBe('hi');
   });
+
+  it('spyOn re-spy', () => {
+    const hi = {
+      sayHi: () => 'hi',
+    };
+    rstest.spyOn(hi, 'sayHi').mockImplementation(() => 'hello');
+
+    expect(hi.sayHi()).toBe('hello');
+    // should get the same spy instance
+    expect(rstest.spyOn(hi, 'sayHi')).toBeCalled();
+  });
 });

packages/core/src/runtime/api/spy.ts

@@ -226,6 +226,22 @@ export const initSpy = (): Pick<
     methodName: K,
     accessType?: 'get' | 'set',
   ): MockInstance<T[K]> => {
+    if (accessType) {
+      const descriptor = Object.getOwnPropertyDescriptor(obj, methodName);
+      const accessor =
+        accessType === 'get'
+          ? Reflect.get(descriptor ?? {}, 'get')
+          : Reflect.get(descriptor ?? {}, 'set');
+      if (typeof accessor === 'function' && isMockFunction(accessor)) {
+        return accessor as MockInstance<T[K]>;
+      }
+    } else {
+      const method = obj[methodName];
+      if (isMockFunction(method)) {
+        return method;
+      }
+    }
+
     const accessTypeMap = {
       get: 'getter',
       set: 'setter',

website/docs/en/api/runtime-api/rstest/mock-functions.mdx

@@ -59,6 +59,19 @@ expect(hi.sayHi()).toBe('hi');
 expect(spy).toHaveBeenCalled();
 ```
 
+If you call `rstest.spyOn` multiple times for the same method, Rstest reuses the existing spy instead of redefining it.
+
+```ts
+const hi = {
+  sayHi: () => 'hi',
+};
+rstest.spyOn(hi, 'sayHi').mockImplementation(() => 'hello');
+
+expect(hi.sayHi()).toBe('hello');
+// should get the same spy instance
+expect(rstest.spyOn(hi, 'sayHi')).toBeCalled();
+```
+
 ## rstest.isMockFunction
 
 - **Alias:** `rs.isMockFunction`

website/docs/zh/api/runtime-api/rstest/mock-functions.mdx

@@ -59,6 +59,20 @@ expect(hi.sayHi()).toBe('hi');
 expect(spy).toHaveBeenCalled();
 ```
 
+对同一个方法重复调用 `rstest.spyOn` 时，会返回已有的 spy，而不是重新定义。
+
+```ts
+const hi = {
+  sayHi: () => 'hi',
+};
+rstest.spyOn(hi, 'sayHi').mockImplementation(() => 'hello');
+
+expect(hi.sayHi()).toBe('hello');
+
+// 返回的 spy 实例与第一次调用相同
+expect(rstest.spyOn(hi, 'sayHi')).toBeCalled();
+```
+
 ## rstest.isMockFunction
 
 - **别名：** `rs.isMockFunction`