class_docstr: Credentials Class Unittest class.
docstr: Test Credentials.activate() already activated.
code: def test_Credentials_activate_already_activated(self):
      """Test Credentials.activate() already activated."""
      c = Credentials.get_current()
      c.activation = _Activation("some_email", True)
      with patch("streamlit.runtime.credentials.LOGGER") as p:
          with pytest.raises(SystemExit):
              c.activate()
          self.assertEqual(p.error.call_count, 2)
          self.assertEqual(
              p.error.call_args_list[1], call("Already activated")
          )
  
imports: import os
  import textwrap
  import unittest
  from pathlib import Path
  from unittest.mock import MagicMock, call, mock_open, patch
  import pytest
  import requests_mock
  from testfixtures import tempdir
  from streamlit import file_util
  from streamlit.runtime.credentials import Credentials, _Activation, _verify_email, email_prompt
label_desc: Use image node_id 15 for calling the CredentialsClassTest obj's underlying member method code with example usage: obj.test_Credentials_activate_already_activated() without return types