class_docstr: Credentials Class Unittest class.
docstr: Test Credentials.activate()
code: def test_Credentials_activate(self):
      """Test Credentials.activate()"""
      c = Credentials.get_current()
      c.activation = None
  
      with patch.object(
          c, "load", side_effect=RuntimeError("Some error")
      ), patch.object(c, "save") as patched_save, patch(
          PROMPT
      ) as patched_prompt:
          patched_prompt.side_effect = ["user@domain.com"]
          c.activate()
          patched_save.assert_called_once()
  
          self.assertEqual(c.activation.email, "user@domain.com")
          self.assertEqual(c.activation.is_valid, True)
  
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 17 for calling the CredentialsClassTest obj's underlying member method code with example usage: obj.test_Credentials_activate() without return types