code: def test_set_credentials(self):
      username, password = "username", "password"
      self.client.set_credentials(username, password)
  
      self.client._service.set_credentials.assert_called_once_with(
          username, password
      )
  
file_path: TabPy/tests/unit/tools_tests/test_client.py
imports: import unittest
  from unittest.mock import Mock
  from tabpy.tabpy_tools.client import Client
  from tabpy.tabpy_tools.client import _check_endpoint_name
label_desc: Use image node_id 8 for calling the TestClient obj's underlying member method code with example usage: obj.test_set_credentials() without return types