(#310) Fixed expected format when saving a screenshot to disk

Author: s1hofmann

lib/screen.class.spec.ts

@@ -411,7 +411,7 @@ describe("Screen.", () => {
             // THEN
             expect(imagePath).toBe(expectedImagePath)
             expect(grabScreenMock).toHaveBeenCalledWith(regionToCapture)
-            expect(saveImageMock).toHaveBeenCalledWith(screenshot, expectedImagePath)
+            expect(saveImageMock).toHaveBeenCalledWith({data: screenshot, path: expectedImagePath})
         });
     });
 });