fix: correctly restore getter

Author: sheremet-va

src/spyOn.ts

@@ -58,10 +58,10 @@ export function internalSpyOn<T, K extends string & keyof T>(
   let objDescriptor = getDescriptor(obj, accessName)
   let proto = Object.getPrototypeOf(obj)
   let protoDescriptor = proto && getDescriptor(proto, accessName)
-  let descriptor = objDescriptor || protoDescriptor
+  let originalDescriptor = objDescriptor || protoDescriptor
 
   assert(
-    descriptor || accessName in obj,
+    originalDescriptor || accessName in obj,
     `${String(accessName)} does not exist`
   )
 
@@ -70,19 +70,19 @@ export function internalSpyOn<T, K extends string & keyof T>(
   // vite ssr support - actual function is stored inside a getter
   if (
     accessType === 'value' &&
-    descriptor &&
-    !descriptor.value &&
-    descriptor.get
+    originalDescriptor &&
+    !originalDescriptor.value &&
+    originalDescriptor.get
   ) {
     accessType = 'get'
     ssr = true
-    mock = descriptor.get!()
+    mock = originalDescriptor.get!()
   }
 
   let origin: Procedure
 
-  if (descriptor) {
-    origin = descriptor[accessType]
+  if (originalDescriptor) {
+    origin = originalDescriptor[accessType]
   } else if (accessType !== 'value') {
     origin = () => obj[accessName as keyof T]
   } else {
@@ -93,7 +93,7 @@ export function internalSpyOn<T, K extends string & keyof T>(
 
   let fn = createInternalSpy(mock)
   let reassign = (cb: any) => {
-    let { value, ...desc } = descriptor || {
+    let { value, ...desc } = originalDescriptor || {
       configurable: true,
       writable: true,
     }
@@ -103,7 +103,9 @@ export function internalSpyOn<T, K extends string & keyof T>(
     ;(desc as PropertyDescriptor)[accessType] = cb
     define(obj, accessName, desc)
   }
-  let restore = () => reassign(origin)
+  let restore = () => originalDescriptor
+    ? define(obj, accessName, originalDescriptor)
+    : reassign(origin)
   const state = fn[S]
   defineValue(state, 'restore', restore)
   defineValue(state, 'getOriginal', () => (ssr ? origin() : origin))

test/index.test.ts

@@ -31,7 +31,11 @@ test('can spy on method', () => {
     },
   }
 
+  const original = obj.method
+
   let method = spyOn(obj, 'method')
+
+  expect(original).not.toBe(obj.method)
   expect(method.called).toBe(false)
   expect(method.callCount).toBe(0)
   expect(method.calls).toEqual([])
@@ -70,6 +74,7 @@ test('can spy on method', () => {
   expect(method.results).toEqual([ok('a!'), ok('b!'), ok('C!'), error(err)])
 
   method.restore()
+  expect(original).toBe(obj.method)
   expect(obj.method('e')).toBe('e!')
   expect(calls).toEqual(['a', 'b', 'e'])
   expect(method.callCount).toBe(4)
@@ -585,6 +590,10 @@ test('no descriptor', () => {
   expect(count).toBe(42)
   expect(getter.called).toBe(true)
   expect(getter.returns[0]).toBe(42)
+
+  spy.restore()
+
+  expect(head.appendChild).toBeTruthy()
 })
 
 test('throw error', () => {
@@ -685,3 +694,14 @@ test('does not await on non-promise values that contain .then', async () => {
   const spiedResult = spied().addValue('Hello').addValue('World')
   expect(spiedResult).toStrictEqual(originalResult)
 })
+
+test('.restore correctly restores primitive property', () => {
+  const obj = {
+    test: 42
+  }
+  const spy = spyOn(obj, { getter: 'test' })
+  spy.willCall(() => 10)
+  expect(obj.test).toBe(10)
+  spy.restore()
+  expect(obj.test).toBe(42)
+})