[GREEN] Passed test for email/username already exist.

authentication/views.py

@@ -13,6 +13,8 @@ def post(self, request):
         username = data['username']
         password = data['password']
         email = data['email']
+        if AppUser.objects.filter(username = username).exists() or AppUser.objects.filter(email = email).exists():
+            return JsonResponse({'msg': 'Username and/or email already taken!'}, status=400)
         if username == '' or password == '' or email == '':
             return JsonResponse({'msg': 'Empty input! Make sure all the fields are filled.'}, status=400)
         if re.match(r'^[\w\.-]+@[\w\.-]+\.\w+$', email) is None: