fix(jasmine-globals): fix transform for existing spyOn (#580)

* fix transform for existing `spyOn`

* call `mockRestore` for existing spies

Author: puglyfe

src/transformers/jasmine-globals.test.ts

@@ -28,6 +28,7 @@ test('spyOn', () => {
     jest.spyOn(stuff).and.resolveTo('lmao');
     jest.spyOn(stuff).and.rejectWith('oh no');
     const fetchSpy = spyOn(window, 'fetch').and.resolveTo({json: {}});
+    existingSpy.and.callThrough();
     `,
     `
     jest.spyOn().mockReturnValue();
@@ -42,6 +43,7 @@ test('spyOn', () => {
     jest.spyOn(stuff).mockResolvedValue('lmao');
     jest.spyOn(stuff).mockRejectedValue('oh no');
     const fetchSpy = jest.spyOn(window, 'fetch').mockResolvedValue({json: {}});
+    existingSpy.mockRestore();
     `
   )
 })

src/transformers/jasmine-globals.ts

@@ -161,10 +161,17 @@ export default function jasmineGlobals(fileInfo, api, options) {
         // if it's `*.and.callThrough()` we should remove
         // `and.callThrough()` because jest calls through by default
         case 'callThrough': {
-          const { callee } = path.node.callee.object.object
-          const arg = path.node.callee.object.object.arguments
-          path.node.callee = callee
-          path.node.arguments = arg
+          // if this comes from an `Identifier` (e.g. `existingSpy.and.callThrough()`),
+          // we assume the intent is to restore an existing spy
+          // to its original implementation using `*.mockRestore()`
+          if (path.node.callee.object.object.type === 'Identifier') {
+            path.node.callee.object = path.node.callee.object.object
+            path.node.callee.property.name = 'mockRestore'
+          } else {
+            // otherwise, we just remove the `.and.callThrough()`
+            // since this is the default behavior in jest
+            j(path).replaceWith(path.node.callee.object.object)
+          }
           break
         }
         // if it's `*.and.callFake()`, replace with jest's